tag:blogger.com,1999:blog-78264611457391846032024-03-14T05:09:09.007+07:00Water WorldAll You Need To Know About WaterCinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comBlogger102125tag:blogger.com,1999:blog-7826461145739184603.post-2347362915362856432013-07-16T23:34:00.000+07:002019-03-23T07:49:48.650+07:00Biochemistry (Water and Life)<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;">Water and Life</td></tr>
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Water is found in all forms of life on Earth in some form or another. The human body is about 70% water, and other organisms, such as jellyfish, contain as much as 95% water. All of the oxygen that animals breathe had its origin as water. During <a href="http://lifeofplant.blogspot.com/2011/03/photosynthesis.html" target="_blank">photosynthesis</a> (the process of using light to create food energy), plants break water apart to produce oxygen and food.<br />
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Water is one of the most abundant molecules on Earth. There are approximately 350 million cubic miles (1.4 billion cubic kilometers) of water on the planet. Nearly 97% of all water is found in the oceans, which cover two-thirds of the surface area of the planet. <br />
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About 90% of all fresh water is frozen in the ice in the North and South Poles and <a href="https://watersome.blogspot.com/2012/09/glaciers.html" target="_blank">glaciers</a> (large slow-moving masses of ice). Less than 1% of all the water on Earth is available for consumption, and most of it is found in aquifers (porous rock chambers holding fresh water) underground.<br />
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<b>Characteristics of water</b><br />
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Water is a simple, yet extremely important, molecule comprised of one oxygen atom and two hydrogen atoms (an atom is the smallest part of an element that has all the properties of the element, and a molecule is two or more atoms held together by chemical bonds). The water molecule’s small size and biochemical properties allow it to bond easily with other molecules. In fact, water is involved in almost every biological reaction.<br />
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Water has many chemical and physical properties that make it useful to cells and organisms. Water acts as a solvent (a liquid in which other substances are dissolved). Water sticks to itself and to other things, which allows it to flow slowly and to fill small places. <br />
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Water is the only material that can exist naturally as a solid, liquid, and gas at Earth’s natural temperatures. It takes a lot of energy to change the temperature of water, so water maintains stable temperatures well. Water also transmits light, allowing photosynthesis to occur underwater.<br />
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<b>Water is polar</b><br />
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Water is composed of one oxygen atom and two hydrogen atoms. The oxygen atom has eight positively charged particles, called protons, and eight negatively charged particles, called electrons. The protons move about in the nucleus (center of the atom). The electrons spin around the nucleus in what are called electron shells or orbitals. <br />
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Different orbitals hold different numbers of electrons. The first orbital contains two of these electrons and the second orbital contains six. Hydrogen atoms contain one proton and one electron. When water forms, electrons are shared between each of the hydrogen atoms and the oxygen atom. <br />
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The sharing of an electron between two atoms forms a covalent bond (this is not a physical bond, atoms do not touch). The covalent bonds result in full outer orbitals for both atoms: eight in the second orbital of the oxygen and two in the first orbital of the hydrogen.<br />
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Positive and negative electrical charges attract each other, like two positive charges repel each other. Because oxygen has more protons than hydrogen, it has a greater positive charge. That causes the spinning electrons in the water molecule to be attracted to the oxygen. This results in extra negative charge in the oxygen part of the molecule, and a positive charge on the hydrogen part.<br />
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The oxygen molecule takes on a “V”-shape, with the oxygen part of the molecule at the bottom of the “V” and the hydrogens at the arms. The bottom of the “V” has a small negative charge, while the arms of the “V” have a small positive charge. This type of molecule is referred to as a polar molecule, because it has a positive pole (the bottom of the “V”) and negative poles (the arms of the “V”).<br />
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The polarity of water molecules allows them to interact with each other electrostatically (due to their charges). The positive pole of one water molecule will be attracted to one of the negative poles of another water molecule. This sort of attraction is called a hydrogen bond. Hydrogen bonds are weak bonds; they easily form and are broken. Each water molecule has the potential to form four hydrogen bonds with other molecules.<br />
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<tr><td class="tr-caption" style="text-align: center;">Water sticks together</td></tr>
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<b>Water dissolves polar substances</b><br />
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Some molecules are made up of ions. Ions are atoms that have either lost or gained electrons. If the atom has lost electrons, it is positively charged. If the atom has gained elections, it is negatively charged. Ionic bonds form between positively and negatively charged atoms. In these molecules, no electrons are shared; instead, the atoms are held together by their opposite charges.<br />
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When ions are mixed with water, the positively charged atom is attracted to the negative poles of water molecules and the negatively charged atom is attracted to the positive poles of water molecules. Eventually, the attraction between the different parts of the ion and the water molecules will pull the ion apart, breaking the ionic bond and dissolving the ion into positively charged atoms and negatively charged atoms. The fact that water is effective at dissolving ions makes it a good solvent.<br />
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Molecules that are polar are able to dissolve easily in water. These substances are often called hydrophilic (or water-loving). Examples of hydrophilic molecules are table salt and table sugar (glucose). Some molecules, however, do not dissolve well in water. These molecules are not polar and they are termed hydrophobic (water-hating). Examples of hydrophobic molecules are fats and proteins.<br />
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The membranes (layers) that surround cells are made up of large fats and proteins that cannot be dissolved in water. However, because water is a small molecule, it can pass through these membranes. As a result, water can transport small nutrients that cells need through cell membranes without destroying any cell membranes and without requiring an input of energy. Similarly, water can transport small waste molecules out of cells.<br />
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<b>Water sticks together</b><br />
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The hydrogen bonds formed between water molecules allow water to stick to itself. This is important for many biological purposes. For example, the surface tension (a force that controls the shape of a liquid) of water allows some animals, such as water striders (spidery-like water insects), to walk on its surface. When rain falls onto Earth, the viscosity (resistance to flow) of water slows the rate it flows over the surface, allowing more water to absorb into the soil where it can be used by plants.<br />
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<b>Water changes temperature slowly</b><br />
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Oceans and lakes change temperature very slowly due to the amount of energy needed to alter the water’s temperature. Thus, as water covers so much of Earth (nearly three-fourths of the planet), the planet has relatively stable temperatures. This means that animals and plants that live in water experience a relatively stable environment. Many animals and plants contain a lot of water in their bodies, which helps them minimize body temperature changes as well.<br />
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The energy required to change water from a liquid to a gas is extremely great because many hydrogen bonds must be broken. When a molecule of water gains enough energy to escape all the hydrogen bonds that surround it, it becomes water vapor. As this molecule leaves the liquid water, it takes with it all of its energy. <br />
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This means the water left behind has less energy. This process is known as evaporative cooling. Many animals (like humans) use evaporative cooling to reduce heat in their bodies. Plants also use evaporative cooling to stay cool in strong sunlight.<br />
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<tr><td class="tr-caption" style="text-align: center;">Water both transmits and absorbs light</td></tr>
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<b>Water is found in three states</b><br />
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At the temperatures and pressures found on Earth, water can be found as a gas, liquid, and solid. A notable property of water is that it is densest, and therefore heaviest, at about 39°F (4°C). Water turns to ice at even colder temperatures, 32°F (0°C).<br />
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When water turns to ice, it gains a crystal-like structure. In this form, nearly all the water molecules are joined by the maximum number of hydrogen bonds, which is four. These hydrogen bonds force the water molecules to move away from each other compared to when they are in the liquid state. <br />
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As a result, water expands when it is frozen. As it expands, it becomes less dense and, therefore, floats on liquid water. As a result, ice is lighter than cold water and so it floats on top of it. If it were not for this unique structure, ice could form in deep water throughout lakes and oceans, making it very difficult for animals to exist there in cold climates.<br />
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<b>Water both transmits and absorbs light</b><br />
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Water has the property of transmitting some types of light, while absorbing or scattering others. The ways that different types of light interact with water benefits life on Earth. Ultraviolet light, which has very small wavelengths, can damage cells. <br />
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However, water vapor in the atmosphere (mass of air surrounding Earth) absorbs light in the ultraviolet wavelengths, greatly decreasing the amount of ultraviolet light that reaches the Earth’s surface. Blue and green wavelengths of light can pass through water relatively easily. These are wavelengths that are most effectively used by plants for photosynthesis. <br />
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As a result, plants can grow and flourish in underwater environments such as lakes and oceans. Water strongly absorbs red wavelengths of light, which produce a lot of heat. Because water vapor is found throughout the atmosphere, much of the red light that hits the Earth is absorbed by water. This aids in keeping the temperature of the Earth warm enough for life to exist.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-15230273455093130152013-07-16T21:11:00.003+07:002019-04-12T08:42:32.754+07:00Chemistry of Water<div class="separator" style="clear: both; text-align: center;"><a href="https://abouthealthsome.blogspot.com/2016/06/prostate-cancer.html" imageanchor="1" rel="nofollow" style="margin-left: 1em; margin-right: 1em;" target="_blank"><img border="0" src="https://1.bp.blogspot.com/-x735MgtT4WM/UeVLswTLXqI/AAAAAAAABko/j-tuELITBII/s1600/water-molecule.jpg" /></a></div><br />
Water is the most common substance on Earth, covering almost three quarters of the planet’s surface. Known by its chemical symbol, H2O, water is the only known substance on Earth that naturally exists as a gas, liquid, and solid. The vast majority of water, about 97%, is in the oceans. <br />
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The liquid form of water also exists in lakes, rivers, streams, and groundwater (water beneath Earth’s surface that is held between soil particles and rock, often supplying wells and springs). In its solid form, water makes up sheets of ice on the North and South Poles, and permanent snow. <br />
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Water also exists as water vapor (gas) in the atmosphere. The hydrosphere is the whole body of water that exists on or around Earth, which includes all the bodies of water, ice, and water vapor in the atmosphere. All life needs water to survive and the cells of all living things contain water.<br />
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Chemistry is the science of the composition, structure, and properties of all substances, called matter, that have mass and occupy physical space. On Earth, the unique chemistry of water determines, in large part, not only the chemistry of the hydrosphere, but also the chemistry of the solid Earth (geochemistry), the atmosphere (atmospheric chemistry), and the living Earth (biochemistry).<br />
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<b>The water molecule</b><br />
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Water is made up of the elements hydrogen and oxygen. An element is a substance that cannot be divided by ordinary chemical means. Hydrogen, oxygen, nitrogen, silicon and iron are all common elements on Earth. Atoms are the building blocks of elements and all matter. An atom is the smallest particle that has the characteristics of an element. Water is composed of groups of atoms called molecules. <br />
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A group of atoms arranged in a particular way makes up a molecule, which is the smallest unit of a substance that has the properties of that substance. Atoms and small molecules like water are so small that they cannot be seen with even the most powerful microscopes. Much of what is known about water molecules has been inferred from indirect observations and chemical experiments.<br />
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A water molecule is a group of three atoms arranged in a shape similar to Mickey Mouse’s head; Mickey’s face is a larger oxygen atom (symbolized by the letter O) and his ears are two smaller hydrogen atoms (symbolized by H2). <br />
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Strong chemical bonds, called covalent bonds, hold the hydrogen and oxygen atoms together. To form covalent bonds, atoms share subatomic particles (particles smaller than atoms) called electrons, which have a negative charge. Atoms also have subatomic particles that have a positive charge, called protons.<br />
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In a water molecule, H2O, more of the shared electrons collect around the oxygen atom than around the hydrogen atoms. This gives the oxygen end of the molecule a negative electrical charge and the hydrogen ends a positive electrical charge. This property of the water molecule, called dipolarity, gives water many of its chemical and physical characteristics.<br />
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<b>Chemical properties of water</b><br />
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<tr><td class="tr-caption" style="text-align: center;">surface tension</td></tr>
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In chemistry, positive and negative electrical charges attract each other, like charges (two positive charges) repel each other. The negative ends of dipolar water molecules are attracted to molecules and atoms with positive charges, and vice versa. <br />
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The molecules within a raindrop, storm cloud, and ice cube are arranged with positive and negative poles (opposite sides of the atom) attached to one another. The positive charge near the hydrogen atoms and the negative charge near the oxygen results in the formation of a hydrogen bond.<br />
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The many hydrogen bonds between the liquid water molecules cause these molecules to stick together. Water molecules at the surface form even stronger hydrogen bonds with their neighboring molecules, causing the formation of a surface film (layer). This phenomenon is called <b>surface tension</b>. Water’s high surface tension makes it more difficult for solid objects to penetrate the water surface than for submerged objects to move through water. <br />
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Certain water bugs can walk on the film due to water’s surface tension. Water forms bubbles and drops because surface tension pulls the shape of unconfined liquids into a ball. (Without deformation by forces like gravity, all raindrops and bubbles would be perfectly sphere-shaped.) A person washes cleaner in a hot bath than a cold one because hot water has lower surface tension than cold, making it better able to get into openings. Soaps and detergents also lower surface tension.<br />
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Surface tension is also partly responsible for capillary action (water’s ability to rise in a small narrow tube called a capillary). Water molecules stick, or adhere, to the sides of the capillary, and surface tension forms a curved bridge, called a meniscus, across the opening.<br />
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Adhesion at the capillary walls creates an upward force and cohesion holds the water surface together. The whole meniscus moves up or through the capillary. Water moves up through plant roots to leaves by capillary action. Capillaries carry blood through the human body. (Human blood is about 83% water.) <br />
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Surface tension and other properties of the water molecule allow nutrients to enter and wastes to leave plant and animal cells. Surface tension aids in the exchange of oxygen and carbon dioxide in the human lungs. Groundwater moves through soil and rock openings by capillary action.<br />
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<b>Water, the universal solvent</b><br />
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Water is called the universal solvent because many solid substances dissolve easily into water. Water molecules form hydrogen bonds with electrically charged atoms called ions and dipolar molecules other than water molecules. Table salt, for example, is composed of a positive ion, sodium (Na+), and a negative ion, chlorine (Cl–). <br />
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In a salt molecule, the sodium and chlorine ions bond to one another. When table salt is dropped in water, the positive ends of the water molecules surround the chlorine and the negative ends surround the sodium. The salt molecule disappears, but its ions are still in the water. <br />
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A liquid that contains dissolved ions is called a solution. When conditions in the solution change in some instances, the dissolved ions bond to one another and turn back into a solid, a process called precipitation. When the water in salt water evaporates, salt molecules reform.<br />
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Water on Earth is an ever-changing solution that dissolves and precipitates substances as it flows. Pure water has no smell, taste, or color. Most water on Earth, however, contains many dissolved materials. Seawater, for example, is a complex solution that contains traces of almost every naturally occurring element. Falling rainwater contains dissolved carbon dioxide. <br />
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“Hard” water (water that contains minerals) that forms scale (crusty deposits) on the hot water heater and makes it hard to lather up for a shower contains dissolved magnesium and calcium. Water that stains a porcelain sink red contains dissolved iron. Water that smells like rotten eggs contains <a href="https://abouthealthsome.blogspot.com/2016/04/sulfur.html" rel="nofollow" target="_blank">sulfur</a>. Many cities and neighborhood water districts add fluoride to the tap water because it prevents tooth decay. <br />
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Some dissolved materials such as lead, mercury, arsenic, petroleum, and <a href="https://lifeofplant.blogspot.com/2011/03/pesticides.html" rel="nofollow" target="_blank">pesticides</a> (chemicals used to kill insects, rodents, and other pests) are hazardous to human and animal health, and can be absorbed by food crops that are irrigated with contaminated water. The United States has set drinking water standards to prevent harmful chemicals from entering the drinking water supply.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-1332030341859997162013-07-16T20:15:00.002+07:002017-10-18T00:24:17.606+07:00Hydrologic Cycle<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;">Hydrologic Cycle</td></tr>
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Water is in constant motion. Energy from the sun and the force of gravity drive the hydrologic cycle, which is the endless circulation of water between the land, <a href="http://watersome.blogspot.com/2011/11/shipping-on-oceans.html" target="_blank">oceans</a>, and atmosphere (air surrounding Earth). Water also changes in form: from gas (water vapor), to liquid, to solid (ice). Rain and snow falling on the land runs off into streams and lakes, or soaks into soil and rocks. <br />
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Streams and rivers carry water downhill to lakes and, ultimately, to the ocean. Heat energy from the Sun transforms liquid water at the surface of lakes and oceans and other bodies of water into water vapor. Water vapor in the atmosphere rises and forms clouds. Cooling within clouds causes water vapor to become liquid once again. Rain and snow fall and the cycle begins anew.<br />
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<b>The water budget</b><br />
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Earth’s water budget, the total amount of water on the planet, does not change over time. The hydrologic cycle is a closed system. Water is constantly moving and changing form, but it is neither created nor destroyed. With the exception of a very small amount of water added to the hydrologic system by volcanic eruptions and meteors from space, Earth’s total water supply is constant. <br />
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In fact, most of the water on Earth today has been recycling through the hydrologic system for billions of years. The same water that comes from a kitchen faucet today could have been drunk by a dinosaur 170 million years ago during the Jurassic Period. It could have been frozen in an ice sheet during the Pleistocene Epoch (a division of geologic time that lasted from 2 million to 10,000 years ago), and could have flowed through a canal in the <a href="http://earlyworldhistory.blogspot.com/2012/02/roman-empire.html" rel="nofollow" target="_blank">Roman Empire</a> two thousand years ago. <br />
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It could have been snow in the Rocky Mountains last winter, flowed in a river to the city’s municipal water intake, and out of the faucet this <a amzn-ps-bm-asin="0979019710" class="amzn_ps_bm_tl" data-amzn-link-id="e3ecf8fab86a1a051e1917188f277168" data-amzn-ps-bm-keyword="morning" href="http://www.amazon.com/Miracle-Morning-Not-So-Obvious-Guaranteed-Transform/dp/0979019710/ref=as_li_bk_tl/?tag=epichistory-20&linkId=e3ecf8fab86a1a051e1917188f277168&linkCode=ktl" id="amznPsBmLink_2775054" rel="nofollow" target="_blank">morning</a><img alt="" border="0" height="0" id="amznPsBmPixel_2775054" src="https://ir-na.amazon-adsystem.com/e/ir?source=bk&t=epichistory-20&bm-id=default&l=ktl&linkId=e3ecf8fab86a1a051e1917188f277168&_cb=1486794752136" style="border: none !important; height: 0px !important; margin: 0px !important; padding: 0px !important; width: 0px !important;" width="0" />. Maybe it will return to the river via the sink drain and city sewage system, and then flow to the ocean.<br />
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<b>Reservoirs</b><br />
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Within the hydrologic system, water resides in environments called reservoirs. Earth’s largest reservoirs, the oceans, contain about 97% of the planet’s total water. Ice, including sheets of ice on the North and South Poles and mountain glaciers (a large body of slow moving ice), and groundwater reservoirs called aquifers hold most of the remaining 3%. Reservoirs of readily useable fresh water— rivers, lakes, soil moisture, atmospheric water vapor, and water in living cells— account for only about 1% of the fresh water, and less than 0.02% of water on Earth.<br />
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If a bathtub filled with 100 gallons (379 liters) of water represented Earth’s total water budget, three gallon (11 liter) jugs would hold all the fresh water, and the fresh water available for immediate use by humans would only fill a tablespoon. A microscope would be needed to see the droplet representing the water bound up in plants and animals.<br />
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<b>Water processes</b><br />
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All of Earth’s water molecules are in constant motion. (A molecule is the smallest particle of a substance that has the chemical characteristics of the substance. A water molecule, symbolized by H2O, is made up of two hydrogen atoms and an oxygen atom.) Processes move water from one reservoir to another and within reservoirs. Liquid water flows downhill and circulates within lakes and oceans. Clouds of water vapor, liquid droplets, and ice crystals (snow) move across the sky. Even molecules bound in glacial ice flow downhill.<br />
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Energy from the Sun and the downward pull of gravity ultimately drive all the processes within the hydrologic cycle. Water cycle processes include evaporation, condensation, convection, precipitation, freezing and melting, groundwater flow, and runoff.<br />
<ul>
<li><a href="http://amzn.to/2kCMALT" rel="nofollow" target="_blank">Evaporation</a> is the conversion of water from a liquid to a gas. Water moves from bodies of water and land to the atmosphere when heat from the Sun transforms liquid water to water vapor. Most (about 80%) of the water vapor in the atmosphere evaporates from the oceans, especially the tropical oceans near the equator. Transpiration is evaporation of water from the leaves and stems of plants. It contributes about 10% of the water vapor in the atmosphere, and evaporation from inland seas, lakes and rivers accounts for the remaining ten percent.</li>
<li><a href="http://amzn.to/2kSyV1S" rel="nofollow" target="_blank">Condensation</a> is the conversion of water from a gas to a liquid. As air containing molecules of water rises in the atmosphere, the air cools, and the motion of the water molecules slows. The slower-moving water molecules accumulate as water vapor in the rising air. Water vapor then forms droplets of liquid water that group together into clouds, and eventually can fall as rain.</li>
<li><a href="http://amzn.to/2kCMQul" rel="nofollow" target="_blank">Convection</a> is the large-scale circulation of the atmosphere and oceans. Warm air or water rises and cool air or water sinks, creating currents (a steady flow in a dominant direction) that transport water around the globe. Convection causes winds that blow rain clouds over the continents, and ocean currents that transport heat, and affect global climate.</li>
<li><a href="http://amzn.to/2kfLPVF" rel="nofollow" target="_blank">Precipitation</a> is the transfer of water from the atmosphere to Earth’s surface. Rain, snow, sleet, and hail are all types of precipitation. When condensed water droplets or ice crystals in a cloud become too large and heavy to remain aloft, they fall to the ground as precipitation. Amounts of precipitation vary greatly between locations. For example, the deserts of the American Southwest receive less than 1 inch (2.5 centimeters) of rain per year, while the summit of Mt. Waialeale on the Hawaiian island of Kauai receives more than 400 inches (1,016 centimeters) of rain per year. Heavy precipitation over a short amount of time can cause rivers and groundwater reservoirs to overflow and lead to flooding. Lack of normal levels of precipitation for an extended period of time causes the dried soil and reduced water supplies associated with drought.</li>
<li><a href="http://amzn.to/2lB1GQs" rel="nofollow" target="_blank">Freezing</a> and melting are the transformations between liquid and solid water. Most freezing occurs in the atmosphere where condensed water vapor forms ice crystals in clouds. Glaciers form in areas near the North and South Poles and in high mountains where more snow falls than melts each year and ice accumulates over many years. In many regions, melting snow and ice replenish river and groundwater flow, as in aquifers, every spring. During the cold winter months in some regions, the surfaces of lakes and rivers freeze. In polar regions, even the seawater and groundwater freeze.</li>
<li><a href="http://amzn.to/2kvM6Vo" rel="nofollow" target="_blank">Groundwater flow</a> is the movement of liquid water through the pores (openings) in soils and cavities in rocks near Earth’s surface. Surface water becomes groundwater by soaking into these tiny spaces, which were filled with air. Groundwater then percolates downward to the surface of the water table, the line where all the spaces are saturated (completely full) with water. Water below the water table flows toward areas of lower pressure where it can be released, such as springs or wells.</li>
<li><a href="https://www.amazon.com/gp/product/B00295R1XI/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B00295R1XI&linkId=8d3bc7ceeb2438aaeacfa4b11e962cba" rel="nofollow" target="_blank">Runoff</a> is the transfer of water from the land surface to the oceans via streams and lakes. (Lakes only hold runoff temporarily, and lake water eventually ends up in the ocean.) Runoff consists of precipitation that neither evaporates back into the atmosphere, nor infiltrates into groundwater. Groundwater discharge can also replenish runoff. Excess runoff leads to flooding.</li>
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<b>Dynamic equilibrium and residence times</b><br />
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All water molecules are in motion, but the total volume of water in a particular reservoir stays relatively constant because of a phenomenon called dynamic equilibrium. The processes that remove water molecules from a reservoir are balanced by the processes that add water. <br />
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To illustrate, imagine trying to maintain a constant volume of water in a bathtub with an open drain. When the faucet is adjusted to add water at the same rate as it is draining, the water level stays constant, and dynamic equilibrium is reached.<br />
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In the same way, sea level stays constant because the amount of water evaporating into the atmosphere matches the amount of water entering from rivers and melting glaciers. Over geologic time (the time from the formation of Earth to the present), this balance changes and the sea level rises and falls.<br />
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The atmosphere transfers water from the ocean to the land, but it only holds a tiny portion (.001%) of Earth’s total water. Water has a short residence time in the atmosphere. Almost as soon (usually a few hours) as it evaporates into the air, water vapor condenses and falls again as precipitation. <br />
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Water molecules stay in some <a href="http://watersome.blogspot.com/2012/09/glaciers.html" target="_blank">glaciers</a>, oceans, and groundwater reservoirs for thousands of years, while others only spend a few days or weeks in a reservoir. To maintain dynamic equilibrium, water must leave the reservoir at the same rate that it enters. In reservoirs with very long residence times, a change in the rate of water that enters or leaves can quickly affect the reservoir volume. <br />
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For example, the Ogallala <a href="http://watersome.blogspot.com/2012/09/groundwater.html" target="_blank">groundwater</a> reservoir in the U.S. Great Plains region is a sandstone (rock formed from the compaction of sand) layer that filled with water a thousand years ago when the climate was wetter. In modern times, ranchers in Texas, Oklahoma, Kansas, Nebraska, and other states are using up the stored groundwater by withdrawing it much more quickly than it replenishes in today’s dryer climate.<br />
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<b>The hydrologic cycle as a component of the Earth system</b><br />
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The hydrologic cycle is intertwined with the other cycles that make up the Earth system. Moving water chemically and physically erodes (wears away) the solid Earth. It transports sediments (fine soil and other particles) and deposits them in river floodplains (lands near rivers that disperse overflow), deltas (where a river enters a lake or ocean, and continental margins (edges of continents that are underwater). It sculpts the land surface and seafloor. <br />
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Water carries dissolved minerals and nutrients that nourish freshwater and <a href="http://watersome.blogspot.com/2011/11/marine-biology.html" target="_blank">marine</a> ecosystems. Water in the oceans and atmosphere regulates Earth’s climate and weather, which makes the planet habitable for biological life. Water is the largest component of most biological organisms. Jellyfish are more than 90% water. If a person weighs 120 pounds (54 kilograms), about 72 pounds (33 kilograms) of his or her weight is water.<br />
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Water is Earth’s most essential renewable resource. It is conserved within the Earth system and cannot be “used up.” However, water is very scarce in some regions and overly abundant in others. <a href="http://lifeofplant.blogspot.com/2011/04/deserts.html" rel="nofollow" target="_blank">Deserts</a>, rainforests, canyons, droughts, and floods all result from the uneven <a href="http://marketingatoz.blogspot.com/2011/04/distribution-and-channels.html" rel="nofollow" target="_blank">distribution</a> of water on Earth. <br />
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Scientists have concluded that human activities such as damming rivers, polluting waters, transporting water to arid (dry) regions to grow crops, and contributing to global climate change can alter the hydrologic cycle and change the patterns of water distribution. Water is continuously recycled and is ultimately a renewable resource, but challenges remain to manage water resources as the <a href="http://lifeofplant.blogspot.com/2011/03/human-population-growth.html" rel="nofollow" target="_blank">human population grows</a>.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-83693252812902000342013-07-16T19:25:00.002+07:002019-04-29T05:26:43.186+07:00Physics of Water<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;">Physics of Water</td></tr>
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Why is water wet? Many people will answer this question by simply saying, “Because it is.” The physical properties of water are fundamental to life and nature on Earth, and are often accepted as simple truths. Water is so common on Earth that its physical characteristics have a large impact on the physics of Earth in general. (Physics is the study of matter and <a href="http://watersome.blogspot.com/2011/11/wave-energy.html" target="_blank">energy</a>, and of interactions between the two.) <br />
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Water covers almost three quarters of the planet’s surface. It is the only natural chemical substance that exists as a liquid, solid (ice), and gas (water vapor) within Earth’s normal temperature range. Water is liquid in a range critical for biological life (0–100°C, 32–212°F), and liquid water is present almost everywhere on Earth. Water’s ability to absorb heat regulates Earth’s <a href="https://watersome.blogspot.com/2012/09/climate.html" target="_blank">climate</a> and <a href="https://watersome.blogspot.com/2012/09/weather.html" target="_blank">weather</a>.<br />
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<b>Phase changes</b><br />
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Matter exists in three states, or phases: solid, liquid, and gas. (Matter is anything that has mass and takes up space). Substances like water change from one phase to another at specific temperatures and pressures. Add heat (or pressure), and a substance begins to change from a solid to a liquid at its melting point. Add more heat, and the substance will begin to evaporate, to turn from liquid to gas, at its boiling point. <br />
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Remove heat (or pressure), and a substance will condense from gas to liquid and then freeze from liquid to solid. In water’s solid phase, its molecules are bound together in a rigid framework called a crystal. (A molecule is a collection of two or more atoms held together by chemical bonds and an atom is the smallest unit of an element.) <br />
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A water molecule, known by its chemical symbol H2O, is a group of two hydrogen atoms and one oxygen atom. In liquid water, the molecules are still attached, but less strongly so, and they can move more freely. The molecules in water vapor are completely detached from one another and mingle with other types of atoms and molecules in air.<br />
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Phase changes either use or release heat energy. Melting and boiling are endothermic phase changes; they absorb heat. The opposite processes, freezing and condensing, release heat and are called exothermic phase changes. A block of ice, sitting in the sun, warms to the melting point of water (0°C or 32°F at sea level on Earth) and then begins to melt. <br />
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The ice stays at exactly 32°F until it has completely melted. In this endothermic process, the heat is breaking the bonds between molecules within the ice crystal. Once the ice has melted, the resulting liquid water begins to absorb heat and the water temperature rises. <br />
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When water temperature reaches the boiling point, 212°F (100°C), the chemical bonds between molecules break, and the water evaporates into its gas phase. Again, the liquid water stays at exactly 212°F (100°C) until the phase change is complete. During exothermic reactions, the temperature likewise remains the same until enough heat has been released for the phase change—melting for example—to become complete.<br />
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Pressure changes can also cause phase changes. Mountaineers in the <a href="https://www.amazon.com/gp/product/B0197I1W7K/ref=as_li_ss_tl?ie=UTF8&linkCode=ll1&tag=waterabout-20&linkId=1a236425b03cf79ec49cee4a0bbcfa3f&language=en_US" rel="nofollow" target="_blank">Himalayas</a> can have trouble cooking their food because water boils at a lower temperature at high altitude (air pressure decreases at high altitude). For this reason, they sometimes carry pressure cookers that raise the temperature in the pot by trapping steam and raising the pressure. <br />
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Cake mixes have special highaltitude cooking instructions printed on the box. Ice-skaters can slide across the ice because the pressure of their skate blades temporarily melts the ice and forms a slippery film of liquid water.<br />
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<b>Liquid water</b><br />
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Molecules in liquid water stick together. It takes a lot of heat energy to break the electrical attractions, called hydrogen bonds, between water molecules. Because of this, water has a high specific heat; it can absorb a lot of heat energy before it changes temperature. In general, heating raises the temperature in a liquid by making its molecules move faster in relationship to one another. <br />
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In water, some of the heat energy is used to break the hydrogen bonds between molecules. When water cools, hydrogen bonds reform, and heat is released. Because of its high specific heat, liquid water can store a lot of energy, a property that has significant consequences for Earth’s climate and biological life.<br />
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The oceans, Earth’s massive reservoirs of liquid water, store and distribute heat energy from the sun. They absorb intense sunlight during the daytime and summer, and then release it slowly during the night and wintertime in the form of ocean currents. <br />
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These currents carry stored heat from the tropics near the equator (an imaginary line around the Earth between the North and South Poles) toward the North and South Poles. Coastal and wet climates are usually milder than inland or arid (dry) climates. <br />
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Water temperature stays relatively constant in the oceans, creating a stable environment for marine (ocean) ecosystems (communities of living organisms). Water protects organisms from temperature changes. Humans, who are composed mainly of water, can survive extreme hot and cold partly because water’s high specific heat maintains <a href="https://www.amazon.com/gp/product/1465449183/ref=as_li_ss_tl?ie=UTF8&linkCode=ll1&tag=waterabout-20&linkId=83776cec8a02860a38861d73c4ca0a90&language=en_US" rel="nofollow" target="_blank">human body</a> temperatures at around 98.6°F (37°C).<br />
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<b>Solid water: ice</b><br />
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<tr><td style="text-align: center;"><a href="https://abouthealthsome.blogspot.com/2019/02/eyebright.html" imageanchor="1" rel="nofollow" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;" target="_blank"><img alt="Ice" border="0" src="https://3.bp.blogspot.com/-BZW333BboCc/UeU42QkKqTI/AAAAAAAABj4/tsdlWd89EIs/s1600/ice.jpg" title="Ice" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ice</td></tr>
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Ice floats. Most liquids contract (draw together) as they cool and reach their maximum density (mass per unit of volume) as a solid. Water is different. It contracts until it reaches about 39°F (4°C), and then it expands until its molecules have all frozen into water’s crystalline form at 32°F (0°C). <br />
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So, cold water sinks, but ice floats. Water is the only natural substance on Earth that is less dense as a solid than as a liquid. If not for this property of water, bodies of water would freeze from the bottom up, ice cubes would sink in a water glass, and there would be no such thing as an iceberg (chunks of floating ice).<br />
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<b>Gaseous water: water vapor</b><br />
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Water’s phase transformation from liquid to gas occurs when molecules in liquid water escape and rise to mingle with other types of molecules and atoms in the <a href="https://www.amazon.com/gp/product/B07571H9XP/ref=as_li_ss_tl?ie=UTF8&linkCode=ll1&tag=waterabout-20&linkId=6cd1de973d3a702f047c4e74fe6bc8ce&language=en_US" rel="nofollow" target="_blank">atmosphere</a> (mass of air surrounding Earth). Boiling occurs when the temperature within a volume of liquid reaches the point at which all the molecules are vibrating too rapidly to stay bonded to each other. Bubbles of gas escape, and eventually the liquid is gone. <br />
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Water molecules also enter the gaseous phase by evaporation from the water surface. Water molecules in liquid water are constantly moving. Even at low temperatures, a percentage of the lessconfined surface molecules move enough to break their bonds to their neighbors and escape into the atmosphere. Water from Earth’s oceans, lakes, and rivers enters the atmosphere by evaporation and, fortunately for life on Earth, not by boiling.<br />
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It takes a lot of heat to break the hydrogen bonds in liquid water and to form water vapor. And, water vapor molecules’ attraction to one another causes them to condense easily into liquid water droplets. Water prefers to be liquid. Water evaporating from the surfaces of Earth’s oceans and other water reservoirs transfers heat into the atmosphere. <br />
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When water vapor condenses into liquid droplets in clouds, heat is released and the air stays warm. Water vapor is an important greenhouse gas in Earth’s atmosphere. A greenhouse traps heat in the atmosphere. Natural greenhouse gases in the atmosphere keep Earth warm, but not too warm. Water vapor’s phase changes from liquid to gas and back to liquid act to trap incoming <a href="https://be-eco-friendly.blogspot.com/2010/01/solar-energy-basic-facts.html" target="_blank">solar energy</a>.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://abouthealthsome.blogspot.com/2019/02/facial-massage.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="water vapor from cooling tower" border="0" src="https://3.bp.blogspot.com/-FnbCwaKbS1M/UeU6afh2xCI/AAAAAAAABkI/vapXBD451L0/s1600/water-vapor.jpg" title="water vapor from cooling tower" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">water vapor from cooling tower</td></tr>
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Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-7958415527686360262013-07-16T17:45:00.001+07:002019-05-05T06:55:17.560+07:00Biology of the Oceans<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://abouthealthsome.blogspot.com/2016/05/senior-nutrition.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Biology of the Oceans" border="0" src="https://2.bp.blogspot.com/-oZWewbTVwx8/UeUelFeX1YI/AAAAAAAABjI/FBpGZspUcOs/s1600/Biology-Oceans.jpg" title="Biology of the Oceans" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Biology of the Oceans</td></tr>
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All organisms that live in the ocean are subject to the physical factors of the underwater environment. Some of the more important factors that affect marine (ocean) organisms are light levels, <a href="https://lifeofplant.blogspot.com/2011/03/nutrients.html" target="_blank">nutrients</a> (chemicals required for growth), temperature, salinity (concentration of salt in the water), and pressure. In general, conditions in the ocean are more stable than those on land.<br />
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<b>Light</b><br />
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The amount of light in a certain location controls the growth of the single-celled marine algae called phytoplankton. Phytoplankton are the base of the marine food chain, meaning they are the food for other organisms, who then are the food for higher organisms and so forth. <br />
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These plants convert sunlight and water into the carbohydrates (sugars) they feed on in a process called photosynthesis. Unlike land, where plants generally live on surfaces, in the ocean, light travels through the water allowing <a href="https://lifeofplant.blogspot.com/2011/02/phytoplankton.html" target="_blank">phytoplankton</a> to grow over a vertical distance of nearly 500 feet in some locations (about 150 meters).<br />
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Light intensity decreases with depth in the ocean and some wavelengths (a property of light that determines whether the light is blue, red, ultraviolet, etc.) of light disappear more quickly than others. Blue light extends the deepest into the ocean, while red light is only present near the surface. <br />
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Many factors influence how quickly light disappears. Near the coast, there may be high amounts of sediments (particles of sand, gravel, and silt) in the water and light may only extend 50 feet (15 meters). In the open ocean, the water is particularly clear and light may extend down 500 feet (150 meters).<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://abouthealthsome.blogspot.de/2016/07/pregnancy.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Light" border="0" src="https://4.bp.blogspot.com/-kMcR6vq4xeM/UeUiGgnH7kI/AAAAAAAABjY/BaZY2_VxsZU/s1600/light.jpg" title="Light" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Light</td></tr>
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Because the phytoplankton must live where there is light, their predators live there as well. Many fish, crustaceans (aquatic animals with no backbone and a hard shell), and mollusks (soft-bodied animals without a backbone enclosed in a shell) are found in surface waters where phytoplankton grow. <br />
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Many of these species use light to hunt prey and avoid predators. Light is also important in the life cycles of many fish and invertebrates (animals without a backbone) who use the changing length of the day as a calendar to trigger breeding periods.<br />
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<b>Nutrients</b><br />
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Just as people need nutrients to grow, phytoplankton in the ocean also need nutrients. Nutrients are substances that are required for an organism to grow. Phytoplankton absorb nutrients that are dissolved in the water around them. Some nutrients are abundant in <a href="https://be-eco-friendly.blogspot.com/2010/10/ocean-dumping.html" target="_blank">ocean</a> water: carbon, oxygen, and sulfur. Others are relatively scarce and become even scarcer when phytoplankton are growing rapidly. The two most important of these are nitrate and phosphate.<br />
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Some phytoplankton, like cocolithophores, develop shells made out of calcium carbonate (the same material as mollusk shells). For these organisms, calcium is a nutrient that is often in short supply. Other phytoplankton, like diatoms, produce shells made out of silica, which is also a nutrient that can be scarce in ocean water. Some other nutrients that are needed in very small quantities are iron, copper, magnesium, and zinc.<br />
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<b>Temperature</b><br />
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With the exception of the hydrothermal vents (natural springs that vent warm or hot water on the seafloor) in the deep ocean, the range of temperatures in the ocean is much narrower than that found on land. Land temperatures vary from above 120°F (49°C) to well below freezing. <br />
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Ocean water is rarely above 80°F (27°C) in tropical waters and never below 30°F (–1.9°C), as ocean water freezes at that temperature. Common water temperatures in temperate waters (waters that are not exposed to extremely cold or hot climates) are around 60°F (16°C).<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://be-eco-friendly.blogspot.com/2010/10/mold-pollution.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Temperature" border="0" src="https://3.bp.blogspot.com/-ij1Bf2jN8Ko/U9E1b7WK8yI/AAAAAAAABrc/lT4nviS6nfY/s1600/temperatur-1.jpg" title="Temperature" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Temperature</td></tr>
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Most animals—including most fish—that live in the ocean are ectothermic, which means that their body temperature is close to that of the water in which they live. The root word ecto means “outside” and the root word therm means “temperature.” For these animals, their metabolic rate (the rate at which biochemical processes occur in an organism) is linked to the temperature of water in which the animal lives. <br />
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For example, if two fish of exactly the same species and size are put in two aquariums, but one is three degrees warmer than the other, the fish in the warmer aquarium will eat more, have a faster heart rate, and swim faster.<br />
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Some fish and aquatic insects are endotherms (or, like tuna, are ectotherms that act like endotherms). Endothermic animals generate their own body heat via their metabolism (chemical reactions within the body). The root word endo means “internal.” <br />
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Endotherms can survive in environments that have a very large temperature range. This is demonstrated by whales that migrate from tropical regions to the frigid <a href="http://watersome.blogspot.com/2012/09/arctic-and-subarctic-regions.html" target="_blank">Arctic</a> waters. However, endotherms require large amounts of food to provide the energy they need to keep their bodies warm.<br />
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<i>Salinity </i><br />
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Salinity is the amount of salt found in one kilogram of ocean water. The average salinity in the ocean is 35 parts per thousand (ppt). This means that there are 35 grams of salt per kilogram, or 1,000 grams, of ocean water. In places where rivers flow into the ocean or where there is a lot of runoff from rain, salinity can drop to 6 ppt. In places that receive little fresh water, such as the Red Sea, salinity can be greater than 40 ppt.<br />
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Most marine invertebrates have salinities within their bodies that are very similar to the salinity of the water around them. If the salinity of the water suddenly changes, then it can harm the animals by interrupting its natural osmosis. <a href="https://lifeofplant.blogspot.com/2011/03/osmosis-simple-diffusion-and.html" target="_blank">Osmosis</a> is the tendency for the concentration of water to always be the same on both sides of a semipermeable barrier. (A semipermeable barrier allows some materials to pass through in both directions.) <br />
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The cell barrier of an animal is semipermeable and water can easily flow through it. A change in salinity on the outside of cells will affect the concentration of the water inside cells. For example, if the seawater surrounding a squid suddenly becomes fresher, then osmosis will move water inside squid’s cells. <br />
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If this happens too quickly, the squid’s cells can burst. On the other hand, if the squid suddenly moves to an area of high salinity, the water from inside the squid’s cells will flow out into the environment. The cells will shrink and the squid could die.<br />
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<i>Pressure </i><br />
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At sea level, the pressure is 14.7 pounds per square inch (1 kilogram per square centimeter) or 1 atmosphere. This pressure results from the weight of the atmosphere (mass of air around Earth) pressing down on Earth. Most organisms on land do not notice this pressure since their bodies are built to push upwards with the same force. Water, however, is much heavier than air. For every 33 feet (10 meters) an organism descends in the ocean, an additional atmosphere of pressure is added.<br />
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Descending to great depths in the ocean is difficult for <a href="https://watersome.blogspot.com/2013/07/marine-mammals.html" target="_blank">mammals</a> because of the gasfilled spaces in their bodies. Sinuses and lungs, in particular, are filled with air that has a pressure of 1 atmosphere. These parts of the body collapse when the external pressure becomes too great. <br />
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Humans can only descend to about 3 or 4 atmospheres (100–130 feet; 30–40 meters). Some whales, like the sperm whale, are able to descend to depths of 7,380 feet (2,250 meters). This is equivalent to a pressure of more than 223 atmospheres.<br />
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Most marine animals, like <a href="https://watersome.blogspot.com/2013/07/marine-invertebrates.html" target="_blank">invertebrates</a> and fish, avoid pressure problems by having internal pressures that are the same as those in their surrounding ocean environment. As a result they can move vertically in the ocean without much effect on their bodies.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-33696319224809575562013-07-16T16:27:00.003+07:002019-05-24T07:50:48.863+07:00Coastlines<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://abouthealthsome.blogspot.com/2016/05/sensory-integration-disorder.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Coastlines" border="0" src="https://4.bp.blogspot.com/-AOED0KyIkJo/UeUE3aqfM0I/AAAAAAAAFN8/QyfP51hSxUw/s1600/coastline.jpg" title="Coastlines" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Coastlines</td></tr>
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Coastlines are boundaries between land and water that surround Earth’s continents and islands. Scientists define the coast, or coastal zone, as a broad swath (belt) of land and sea where fresh water mixes with salt water. Land and sea processes work together to shape features along coastlines. Freshwater lakes do not technically have coastal zones, but many of the processes (waves, tides) and features found along ocean coastlines also exist in large lakes.<br />
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<b>Coastal zone features</b><br />
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All coastlines include a thin strip of land that is submerged at high tide and exposed at low tide, called the shoreline. The coastal zone, however, extends far inland from the shore, across lowlands called coastal plains, and far seaward to the water depth where ocean waves do not reach the seafloor. The coastal zone includes lagoons, beaches, estuaries, tidal wetlands, tidal inlets, river deltas, barrier bars and islands, sand bars, and other shallow-water ocean features.<br />
<ul>
<li><a href="https://www.amazon.com/gp/product/B001OD8MX4/ref=as_li_ss_tl?ie=UTF8&linkCode=ll1&tag=waterabout-20&linkId=adcce8cb8981018006c3069036b38a58&language=en_US" rel="nofollow" target="_blank"><b>Lagoons</b></a>: Shallow, salt-water bays between barrier islands and the mainland. </li>
<li><a href="https://amzn.to/2kJeKVN" rel="nofollow" target="_blank"><b>Beaches</b></a>: Sand deposits along shorelines. Intense waves wash fine-grained mud from coastal sediments (particles of sand, gravel, and silt) leaving only sand-sized grains of resistant minerals like quartz and calcium carbonate. Beaches are common on the seaward side of barrier islands where wave energy is intense. </li>
<li><a href="https://www.amazon.com/gp/product/0471974714/ref=as_li_ss_tl?ie=UTF8&linkCode=ll1&tag=waterabout-20&linkId=58847a2a2b61bdc6c2fb620cd65da6ea&language=en_US" rel="nofollow" target="_blank"><b>Estuaries</b></a>: The mouths of rivers and streams that receive a pulse of saltwater with the tides. </li>
<li><b><a href="https://www.amazon.com/Ecology-Freshwater-Forested-Wetlands-Southeastern-ebook-dp-B001BVXTGY/dp/B001BVXTGY/ref=as_li_ss_tl?_encoding=UTF8&me=&qid=&linkCode=ll1&tag=waterabout-20&linkId=9cc9afc4418825dd8279ff0093e627d1&language=en_US" rel="nofollow" target="_blank">Tidal wetlands</a> (flats)</b>: The broad areas of marshy wetlands around lagoons and estuaries that flood with salt water during high tides.</li>
<li><a href="https://amzn.to/2lzLr9E" rel="nofollow" target="_blank"><b>Tidal inlets</b></a>: Openings through which water and sediment are washed in and out of lagoons by daily tides. </li>
<li><a href="https://www.amazon.com/gp/product/1881261131/ref=as_li_ss_tl?ie=UTF8&linkCode=ll1&tag=waterabout-20&linkId=94c5a1f259154ccfeb4bf057f9ccf407&language=en_US" rel="nofollow" target="_blank"><b>Deltas</b></a>: Deposits of sediments at the mouths (ends) of rivers that flow into the ocean. </li>
<li><b>Barrier bars and islands</b>: Long mounds, or bars, parallel to the shore into which near-shore ocean currents carry and deposit sand. Eventually, some barrier bars grow tall enough to stay exposed at high tide and become barrier islands. The outer banks of North Carolina as well as Galveston, Mustang Island, and South Padre Island in Texas are examples of barrier islands. </li>
<li><a href="https://www.amazon.com/gp/product/1432788272/ref=as_li_ss_tl?ie=UTF8&linkCode=ll1&tag=waterabout-20&linkId=ec06584dcd9ad18b77e1d9941a54b523&language=en_US" rel="nofollow" target="_blank"><b>Sand bar</b></a>: A ridge of sand in rivers or along the coast built up by water currents.</li>
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<b>Processes that shape coastlines</b><br />
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The coastal zone is constantly changing. Salt water rushes through tidal inlets into bays and estuaries twice daily. Waves, currents (steady flows of water in a prevailing direction), tides, and storms reshape coastal features over days, weeks, and months. Coastlines move landward and seaward as global sea-level rises and falls over hundreds and thousands of years.<br />
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All coastlines are at least somewhat affected by waves and tides. Waves straighten uneven shorelines by eroding (wearing away) points that extend into the ocean and depositing sediment in bays. They also generate strong, shallow currents that carry and deposit sediment parallel to the shore. Long shoreparallel features like barrier islands, spits (small strips of land that jut out into the sea), and sand bars border coasts where waves are the dominant force. <br />
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Tides move sediment and water in and out across the shoreline, and tide-dominated coasts have features like tidal inlets, natural jetties (protective rock barriers), and funnel-shaped estuaries that form a 90° right angle to the shore. Most coastlines are shaped by both waves and tides, and have some parallel and perpendicular features.<br />
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<b>Types of coastlines</b><br />
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All coastlines are affected by waves, tides, storms, and currents, and every coast includes a shoreline. There are, however, many different types of coastlines. Some coastlines receive large amounts of sand and mud from rivers. Others accumulate the skeletal remains of animals like corals and shellfish. In some places, waves are eroding coastlines that are rising from the sea.<br />
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<i>Depositional coastlines</i><br />
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<tr><td class="tr-caption" style="text-align: center;">Depositional coastlines</td></tr>
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Coasts that receive a steady supply of sediment are called depositional coastlines. Rivers like the Mississippi in the United States and the Nile in Egypt erode sediment from continental interiors and deposit it in huge deltas at their mouths. <br />
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Waves, currents, and tides spread sediment into thin layers on the submerged continental shelf (the shallow seabed that stretches from the shore to the deeper ocean water). Over time, the weight of the sediment presses down on the edge of the continent, creating space for more sediment. New layers build on to the edge of the continent, and the coast moves seaward. <br />
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Depositional coastlines typically encompass a broad coastal plain, and a complex shoreline that includes long, wide beaches. These coastlines are almost flat, causing salt water to move far inland across coastal plains and up rivers during high tide. The Mid-Atlantic and Gulf of Mexico coasts of the United States are depositional coastlines.<br />
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Waves, tides, and currents sort and distribute incoming sediment into distinctive features along depositional coastlines. Some of these features include: barrier bars and islands, tidal inlets, lagoons, beaches, estuaries, and tidal wetlands.<br />
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Depositional coastlines also develop where plants and animals called carbonates live in clear, sunlit water away from river deltas. Carbonates like corals and shellfish have skeletons and shells made of the hard mineral calcium carbonate. The sediment supply on carbonate coastlines comes from the skeletal remains of the animals and plants that live there. Corals build giant ridges of rocks called reefs up from the seafloor. Florida and the Bahamas have carbonate coastlines.<br />
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<i>Erosional coastlines</i><br />
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Erosional coastlines occur where huge sections of the Earth’s crust called tectonic plates lift out of the sea. These coastlines are common along far northern coastlines that are bouncing back after being weighed down by thick ice sheets, and along coasts where tectonic plates meet. Erosional coastlines are the norm in Maine and eastern Canada, along the west coast of North America, and in Scandinavia. <br />
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Along these coasts, waves pound rocky shorelines and cut into the bottoms of cliffs. The shore retreats as blocks of rock and sediment fall into the sea. Isolated remnants of sea cliffs, called stacks, are left standing in the sea. All of these features are caused by movements of plates and wave action over time. The process of shoreline retreat claims much expensive real estate along erosional coastlines.<br />
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<b>Life in the coastal zone</b><br />
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The plants and animals that live in the coastal zone have adapted to its cycles of change. Residents of tidal wetlands tolerate twice-daily drowning and drying. Fish in estuaries and lagoons adjust to large changes in water salinity (saltiness). <br />
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Plants grow with their roots in salt water and can survive burial by shifting beach sand and river mud. Many ocean and land animals spend their early lives in coastal wetlands where there is shelter and plentiful food before moving to dry land or the open ocean as adults. <br />
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Coastlines are also home to about two-thirds of Earth’s human population. People continue to work to understand the nature of coastal zones in order to protect coastal populations from their hazards (storms, waves, floods, erosion), but also to protect coastlines from the damaging effects of everyday human activities, such as eroding sand dunes by climbing them, or generating pollution.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-82774681669120412122013-07-16T06:14:00.003+07:002019-05-31T03:18:20.705+07:00Currents and Circulation Patterns in the Oceans<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
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<tr><td class="tr-caption" style="text-align: center;">Currents and Circulation Patterns in the Oceans</td></tr>
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The oceans are in constant motion. Ocean currents are the horizontal and vertical circulation of ocean waters that produce a steady flow of water in a prevailing direction. Currents of ocean water distribute heat around the globe and help regulate Earth’s climate, even on land. Currents carry and recycle nutrients that nourish marine (ocean) and coastal plants and animals. <br />
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Human navigators depend on currents to carry their ships across the oceans. Winds drive currents of surface water. Differences in temperature and salinity (saltiness) cause water to circulate in the deep ocean. The rotation of the Earth, the shape of the seafloor, and the shapes of coastlines also determine the complex pattern of surface and deep ocean currents.<br />
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Ocean water is layered. The shallowest water, called surface water, is warmer, fresher, and lighter than deep water, which is colder, saltier, and denser. The boundary between surface and deep water is a thin layer marked by an abrupt change of temperature and salinity. This layer, called the thermocline, exists in most places in the oceans. Surface and deep water only mix in regions where specific conditions allow deep water to rise or surface water to sink. <br />
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Many organisms swim freely across the thermocline, and the remains of plants and animals continuously rain down through the deep water to the seafloor. However, most organisms live, or at least feed, close to the ocean surface where microscopic plants called phytoplankton float freely and absorb the sunlight they need to live. Very little light penetrates the surface water.<br />
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<b>Surface currents </b><br />
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Earth’s atmosphere (mass of air surrounding Earth) and oceans together form a “coupled system.” Winds drive circulation of the oceans’ thin upper layer of surface water, and temperature differences in the oceans help to generate atmospheric winds. Friction (resistance to the motion of one surface over another) between the moving air and the water surface pushes water in the direction of the blowing winds. <br />
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Earth’s eastward rotation causes currents to deflect (bend) to the right in the northern hemisphere and to the left in the southern hemisphere, a phenomenon called the Coriolis effect. Coriolis deflection causes clockwise circulation of wind-driven surface ocean currents in the northern hemisphere and counterclockwise circulation in the southern hemisphere.<br />
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<i>Warm surface currents </i><br />
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The subtropical trade winds, or trades, are strong, steady winds that blow warm water from west to east on either side of the equator (an imaginary line around Earth halfway between the North and South Poles), thereby creating west-flowing equatorial currents in the major oceans. <br />
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The trades and equatorial currents push piles of warm water into the western halves of the Pacific, Indian, and Atlantic Oceans. Water flows down and away from the centers of the mounds, not unlike pancake batter spreading out on a griddle. <br />
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The trades continue to push the water to the west, and Coriolis deflection guides it northward in the northern hemisphere and southward in the southern hemisphere. Warm, fast currents, called western boundary currents, flow away from the tropical warm pools toward the poles in the western halves of the ocean basins.<br />
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The Gulf Stream is the western boundary current in the North Atlantic. It flows north along the southeastern coast of the United States and then crosses the Atlantic on a diagonal path. Warm Gulf Stream waters create unusually mild climates in northern locations. Gulf Stream waters keep Bermuda balmy, Ireland green, and England foggy. The Gulf Stream is the major shipping route from North America to Europe. <br />
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The western boundary current in the North Pacific, called Kuroshio, likewise warms the islands of Japan and carries ships toward the Pacific Northwest. Western boundary currents in the southern hemisphere, the Brazil Current in the South Atlantic, East Australian Current in the South Pacific, and Aguellas Current in the Indian Ocean flow south from the equator.<br />
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<i>Cool surface currents</i><br />
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Cold surface currents carry cool water from the poles toward the equator along the west coasts of the continents. The cool eastern boundary currents are generally shallower and weaker than the western boundary currents. Cold water flowing from the Arctic Ocean at the North Pole feeds the eastern boundary currents in the northern hemisphere, namely the California Current in the Pacific and the Canary Current in the Atlantic. <br />
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The Antarctic Circumpolar Current (ACC) that encircles the ice-covered Antarctic continent supplies the cool water to the eastern boundary currents of the southern hemisphere—the Peru, Benguela, and West Antarctic Currents. The ACC is an exception to the general rule that surface currents are shallow. It extends from the sea surface to the seafloor in several places.<br />
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<i>Gyres</i><br />
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<tr><td class="tr-caption" style="text-align: center;">Gyres</td></tr>
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Surface water circulates in oceans in massive circular patterns called gyres. The major surface currents (eastern boundary, western boundary, and equatorial current) in each ocean link to form a circle. Gyres are clockwise in the northern hemisphere and counterclockwise in the southern hemisphere. <br />
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For example, a rubber duck dropped into the ocean near San Diego might float south on the California Current to the North Equatorial Current, west across the Pacific Ocean to the Kuroshio western boundary current, and then back across the northern Pacific to British Columbia. <br />
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In a few years, the California Current might return the duck to San Diego. Ocean researches have actually conducted many such experiments. One important study tracked 29,000 plastic bathtub toys that spilled from a cargo ship in the North Pacific.<br />
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The infamous “triangle trade” between Europe, Africa, and North America in the eighteenth and nineteenth centuries relied on the North Atlantic Gyre. European slave ships arrived in Africa via the Canary Current, then carried slaves to the sugar plantations of the Caribbean on the North Equatorial Current. <br />
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Having left off slaves and picked up sugar, they rode the Gulf Stream north to the rum distilleries of New England and the liquor shops in Europe. Hurricanes that form in the tropical Atlantic ride the North Equatorial Current toward the Caribbean Islands and then follow the Gulf Stream toward the southeast coast of the United States.<br />
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<b>Deep ocean currents</b><br />
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Deep ocean currents are driven by differences in temperature and salinity. They are generally unaffected by surface currents. Deep water is colder, saltier, and denser than surface water. Deep water forms in polar regions where warmer surface water cools and sinks beneath the Arctic ice cap (permanent ice covering) or Antarctic ice shelves (permanent ice large enough to cover most of a land mass). <br />
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Salinity increases near the ice caps because seawater forms freshwater ice when it freezes. The salt stays behind and the remaining liquid water becomes saltier. A “global conveyor belt” carries deep water south through the Atlantic, around Antarctica, and north into the Pacific, Indian, and Atlantic Oceans. It could take the molecules in a drop of water more than a thousand years to make a complete circuit of this global deep ocean current.<br />
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<b>Upwellings and downwellings</b><br />
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<tr><td style="text-align: center;"><a href="http://lifeofplant.blogspot.com/2011/10/bryophytes.html" imageanchor="1" rel="nofollow" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;" target="_blank"><img alt="Upwellings and downwellings" border="0" src="https://2.bp.blogspot.com/-u4-8JtdzfP0/UeSBxdioM1I/AAAAAAAAFNs/zraHvgKUcKc/s1600/Updown-welling.jpg" title="Upwellings and downwellings" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Upwellings and downwellings</td></tr>
</tbody></table>Deep water rises to become surface water at upwellings. Upwellings are most common along coastlines where strong winds blow away from shore, but they also occur in the open ocean where winds blow away from one another. In both cases, winds push the warm surface water away and cold, nutrient-rich deep water rises to the sea surface to replace it. <br />
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Upwellings are common along the west coasts of the continents, particularly in regions beneath the easterly (west-blowing) trade winds. Because they bring important minerals and nutrients from the deep ocean, upwellings typically support abundant marine and coastal life. Upwellings nourish waters rich with life off Peru, California, and southwestern Africa. A divergence between wind patterns creates a zone of intense upwelling that completely surrounds Antarctica.<br />
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Downwellings are ocean zones where surface water sinks into the deep ocean. Downwellings can occur at places were winds meet or blow toward shore. However, warm water does not sink, and warm surface currents are more likely to pile water up against obstacles like coastlines and opposing currents than to force it into the deep ocean. Most deep water forms at intense Arctic and Antarctic downwellings where ice cools the seawater and freezing increases its salinity.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-6740698098733112912013-07-16T04:52:00.002+07:002017-02-14T15:00:49.705+07:00El Niño and La Niña<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://lifeofplant.blogspot.com/2011/10/bulbs-and-rhizomes.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="El Niño" border="0" src="https://2.bp.blogspot.com/-o-EB6o_xe2U/UeRr9fAesII/AAAAAAAAFM0/aXmm_vt5V9M/s1600/elnino.jpg" title="El Niño" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">El Niño</td></tr>
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El Niño and La Niña are changes in the winds and <a href="http://be-eco-friendly.blogspot.com/2010/10/ocean-dumping.html" target="_blank">ocean</a> currents of the tropical Pacific Ocean that have far-reaching effects on global weather patterns. Together, El Niño and La Niña are extremes that make up a cycle called the El Niño Southern Oscillation (ENSO). An oscillation is a repeated movement or time period. El Niño and La Niña events do not occur in a regular or seasonal pattern; instead, they repeat about every two to seven years and last for a few months.<br />
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<b>How El Niño and La Niña Occur</b><br />
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El Niño events occur when the trade winds and equatorial current south of the equator in the Pacific Ocean lessen in intensity. The trade winds, or trades, are strong, steady winds that blow from east to west and drive strong west-flowing ocean currents on either side of the equator. (The trade winds are named for their role in propelling sailing ships carrying cargo to trade around the world.) The equatorial current is a sustained pattern of water flowing westward near the equator. Less dramatic La Niña episodes occur during the opposite conditions, when the tropical winds and currents are unusually strong.<br />
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During normal, non–El Niño conditions, the trade winds and equatorial current in the southern Pacific push warm surface water to the west and allow cold water from the deep ocean to rise along the coast of South America. The southeasterly (northwest-blowing) trades south of the equator usually pile a mound of warm water around the islands of <a href="http://amzn.to/2lewj0e" rel="nofollow" target="_blank">Indonesia</a>, and create a zone of cool water that rises called an upwelling off the coasts of Peru and Ecuador. <br />
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The cold, nutrient-rich waters of the South American upwelling nourish abundant microscopic plants (<a href="http://lifeofplant.blogspot.com/2011/02/phytoplankton.html" target="_blank">phytoplankton</a>) and animals (zooplankton) that provide food for larger sea animals. It is a biologically rich region for fish and land animals, including humans who depend on <a href="http://watersome.blogspot.com/2013/07/fish-saltwater.html" target="_blank">fish</a> for food. The pool of warm water in the western Pacific creates a warm, rainy climate, and the cold water of the upwelling causes an arid (extremely dry) climate in coastal South America.<br />
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Occasionally, for reasons not yet fully understood, the trade winds and southern equatorial current in the south Pacific lessen in strength. Warm water sloshes east toward the central coast of South America and shuts down the South American upwelling. The El Niño phase of an ENSO cycle begins with a dramatic warming of the waters off of South America and a decline of marine (ocean) life. <br />
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<tr><td class="tr-caption" style="text-align: center;">El Niño and La Niña</td></tr>
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La Niña, the opposite phase of an ENSO cycle, occurs when the southeast trades are particularly strong. La Niña events are marked by a strengthening of the South American upwelling and a good fishing season. La Niña events often, but not always, follow El Niño events.<br />
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<b>Discovery of El Niño and La Niña</b><br />
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Peruvian fishermen who depended on the South American upwelling for their livelihoods recognized and named the El Niño phenomenon in the nineteenth century. The fishermen noticed that every few years, the seawater became much warmer and the pattern of ocean currents would change within about a month of Christmas day. <br />
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These changes always marked the start of a very poor fishing season. Normally dry areas along the coast would receive abundant rain. As this typically happened close to Christmas, the fishermen dubbed the phenomenon El Niño, Spanish for “the boy child,” after the Christ child. The other half of the ENSO cycle was named La Niña, “the girl child,” much later.<br />
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El Niño has been a well-known local occurrence in coastal South America for more than 150 years. However, scientists only began to realize that the strong El Niño events were part of a disruption that effected the entire Pacific Ocean in the late 1960s. The effects of the southern oscillation were first recognized (and named) in the western Pacific by Sir Gilbert Walker in 1923. <br />
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Walker was a British scientist who studied the changes in the summer monsoons (rainy seasons) of India. Using meteorological (weather-related) data, he observed that atmospheric pressure (pressure exerted by the air) seesaws back and forth from the <a href="http://amzn.to/2lev55b" rel="nofollow" target="_blank">Indian Ocean</a> near northern Australia, to the southwestern Pacific near the island of Tahiti. <br />
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Walker also noticed that the changes in pressure patterns were related to changes in the weather that affected rainfall, fishing, and agricultural harvests in Southeast Asia and India. In the late 1960s, Jacob Bjerknes, a professor at the University of California, first proposed that the Southern Oscillation and the strong El Niño sea warming were related.<br />
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<b>Effects of El Niño and La Niña </b><br />
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The effects of El Niño on the climate of the tropical Pacific are now well known. As the mound of warm water in the western Pacific collapses and spreads eastward, the area of heavy rain above it shifts to the east. Fewer rain clouds form over the Pacific Islands, Australia, and Southeast Asia. Lush, biologically diverse rain forests dry out and become fuel for forest fires. Usually arid islands in the central Pacific receive heavy rainfall. <br />
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In the eastern Pacific, the ocean upwelling weakens as the warm surface water flows toward South America. The surface water off Ecuador and Peru runs low on the nutrients that support the ocean food chain. Many species of fish and birds go elsewhere to find food, and human fishermen face economic hardship. <br />
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The warmer waters offshore also encourage development of clouds and thunderstorms. Normally dry areas along the west coast of South America experience torrential rains, flooding, and mud slides during the El Niño years. La Niña events are usually less dramatic, but typically cause an opposite effect on the climate (long-term temperature, rainfall, and wind conditions) of the southern Pacific.<br />
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El Niño and La Niña also seem to cause far-reaching changes in the weather and climate in other parts of the world. The altered pattern of winds and temperatures in the tropical Pacific may change the paths of the jet streams (high-level winds) that steer storms across North and South America, Africa, Asia, and Europe. <br />
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El Niños have been linked to mild, wet winters along the west coast of North America, strong storms in the <a href="http://amzn.to/2lex5L4" rel="nofollow" target="_blank">Gulf of Mexico</a>, heavy rains in the American Southwest, and droughts (lack of rain) in Central America and northern South America. In the El Niño years of 1986–87 and 1997–98, California and Chile both experienced torrential rainstorms and heavy snows that led to mudslides. <br />
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El Niño may also affect the Indian monsoons and bring drought to northern Africa, thereby threatening <a href="http://watersome.blogspot.com/2011/11/agricultural-water-use.html" target="_blank">agricultural</a> harvests in India, Asia, and Africa. During La Niña episodes like 1998–99, the northern part of the United States may experience heavy snows, increased rainfall, and cold temperatures, while tornado activity increases in the southern states.<br />
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The far reaching climatic and economic effects of El Niño and La Niña make understanding ENSO a priority for scientists. Improved understanding and forecasting will help populations plan for the effects of El Niños and limit economic suffering and starvation. While El Niño and La Niña do have far-reaching effects, scientists are also careful not to blame all extreme or abnormal weather on the phenomenon, or to draw too many connections between Niño and global climate variations.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-40893644803364377102013-07-15T21:15:00.001+07:002017-02-14T15:09:01.703+07:00Fish (Saltwater)<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2015/11/tibetan-medicine.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Fish (Saltwater)" border="0" src="https://4.bp.blogspot.com/-Lj5TidZEgl8/UeP6AqR748I/AAAAAAAAFL0/2-iqrZ_Utqo/s1600/fish.jpg" title="Fish (Saltwater)" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fish (Saltwater)</td></tr>
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There are over thirty thousand different species of fish, and they are the most numerous vertebrates. Vertebrates are animals that have a bony spine that contains a nerve (spinal) chord. Vertebrates usually have an internal skeleton that provides support and protection for internal organs. This spine and skeleton allow vertebrates to move quickly and to have great strength.<br />
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Fish usually live surrounded entirely by water. They all have gills for breathing and fins for swimming. Most fish are ectotherms, which means that their bodies are nearly the same temperature as the water in which they live. About 60% of all fish live entirely in saltwater, while the rest live in freshwater or both freshwater and saltwater.<br />
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One of the most remarkable things about fish is their diversity. Fish can be very large, like the whale sharks that can reach 90,000 pounds (41,000 kilograms) or very small, like gobies that can weigh as little as 0.0004 ounce (0.1 gram). They have a variety of diets, including plants, other fish, invertebrates (animals without a backbone) and microscopic <a href="http://watersome.blogspot.com/2013/07/plankton.html" target="_blank">plankton</a> (free-floating plants and animals). <br />
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Fish find their food in many different ways, including hunting with their eyes, grazing, scraping the sea floor, and digging. Some fish have special organs that bioluminesce (create light) and lure prey towards their mouths, while others use this glow to make themselves blend in with coral or other ocean features, disguising themselves from predators. <br />
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Fish come in a variety of colors that can serve to scare predators away or blend into their environment. Some fish live their entire lives within one bay or cove, while others may migrate thousands of miles (kilometers) across the ocean. Fish can live alone or they may swim with many other fish, called schools, to protect against predators.<br />
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Fish are classified into three groups. The jawless fish belong to the class Agnatha. They include hagfish and lampreys. The rays and sharks belong to the class Chondrichthyes. They have skeletons that are made of a tough material called cartilage. The bony fish belong to the class Osteichthyes. This largest group includes many familiar fish like tuna, <a href="http://identifyfish.blogspot.com/2010/10/atlantic-halibut-hippoglossus.html" target="_blank">halibut</a>, anchovy, and cod.<br />
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<b>Class Agnatha</b><br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://adf.ly/Aj99y" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;" target="_blank"><img alt="Hagfish" border="0" src="https://2.bp.blogspot.com/-qjfweYGRm18/UeP8sEczizI/AAAAAAAAFME/QBVwAFlmUMo/s1600/Hagfish.jpg" title="Hagfish" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Hagfish</td></tr>
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There are about fifty species of Agnathans and they are divided into two groups: <a href="http://identifyfish.blogspot.com/2010/10/hagfish.html" target="_blank">hagfish</a> and <a href="http://identifyfish.blogspot.com/2010/11/lamprey.html" target="_blank">lampreys</a>. These fish have no jaws and their fins are not evenly matched across their bodies, so they are not efficient swimmers. They have mouths that look like suckers with small teeth that are used for grasping on to prey. Organs for smelling and sensing surround their mouths and help them identify prey. These fish have very poor vision.<br />
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Hagfish live in colonies (groups) on the sea floor. They dig in sediments (sand, gravel, and silt) for worms to eat. If approached by predators, hagfish emit large quantities of foul-smelling slime from glands along the sides of their bodies. This usually discourages or confuses predators. After the danger has passed, the hagfish will tie itself in a knot, which it slides along the length of its body to scrape off the slime.<br />
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The mouth of the lamprey is called an oral disc. It is cone-shaped and contains sharp teeth that it uses to bore a hole into the side of another animal. The lamprey then attaches its oral disk to the live animal’s wound and feeds off the blood and tissue of its host. Lampreys usually detach after some period of time without killing their host. Lampreys are usually most often found attached to bony fish, but they also have been seen on <a href="http://be-eco-friendly.blogspot.com/2011/03/humpback-whale.html" target="_blank">whales</a> and <a href="http://identifyfish.blogspot.com/2010/10/common-dolphin-coryphaena-hippurus.html" target="_blank">dolphins</a>.<br />
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<b>Class Chondrichthyes</b><br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="http://lifeofplant.blogspot.com/2011/12/biomass-related-to-energy.html" imageanchor="1" rel="nofollow" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;" target="_blank"><img alt="Rays" border="0" src="https://3.bp.blogspot.com/-jyjKvTNX0Lk/UeP-qu_0GQI/AAAAAAAAFMU/lPuKhb1CTkw/s1600/rays.jpg" title="Rays" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Rays</td></tr>
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The class Chondrichthyes includes about 700 species of sharks and rays. They are an extremely old group, having been in existence for approximately 280 million years. Nearly all members of this class are marine (live in seawater). These fish have skeletons made out of cartilage, which is a tough but flexible tissue. <br />
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It is the same material that is found in human ears and noses. <a href="http://identifyfish.blogspot.com/2010/09/sharks.html" target="_blank">Sharks</a> and rays do not have gas bladders (internal sacs that fill with gas to help the fish rise or fall in the water so that it does not waste energy by continually swimming). Sharks and rays must continually swim in order to prevent themselves from sinking. <br />
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However, the liver of sharks is large and it contains a lot of oily materials. As oil is less dense than water, this special liver helps the shark stay afloat. Cartilaginous fish have several rows of teeth that fall out as they age. They are then replaced with new teeth that grow in from behind.<br />
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Sharks do not have scales; instead they have rough plates called dentricles embedded in their skin. These dentricles make the skin feel abrasive, like sandpaper. Many sharks have electroreceptors on their heads. These specialized organs allow the shark to sense the electrical currents generated by fish as they swim through the water. The shark’s well-developed nervous system, including a large brain, also helps it locate its prey (animals that are food).<br />
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Rays have a more flattened shape than sharks. Their fins are attached to their bodies so that they look like triangular or semicircular wings. Large rays, like the manta ray, can measure 22 feet (7 meters) from fin to fin. These huge animals feed on plankton. Other rays, like the stingray, have sharp barbs attached to the base of their tail. These are used as defense against predators. Another family of rays can actually produce an electric current, which they can use to stun prey.<br />
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<b>Class Osteichthyes</b><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://earlyworldhistory.blogspot.kr/2012/03/kama-sutra.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Yellowfin tuna" border="0" src="https://4.bp.blogspot.com/-oE29wY6XDbU/UeQBT1HBK7I/AAAAAAAAFMk/Sw9nub0AAMg/s1600/yellowfin-tuna.jpg" title="Yellowfin tuna" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Yellowfin tuna</td></tr>
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The class Osteichthyes, or the bony fish, make up the majority of fish, with almost 28,000 different species. These fish all have a strong, but lightweight, skeleton that supports their organs. They have gas bladders that help them maintain buoyancy. The teeth of bony fish are fused to their jawbone and do not fall out as do the teeth of the cartilinagous fish.<br />
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Osteichthyes are found in every type of marine environment from near-shore tidepools and coral reefs to the very bottom of the deep ocean. Nearly 90% of all the bony fish are categorized into one order, Teleostei. These fish include many common fish, like the cod, <a href="http://identifyfish.blogspot.com/2010/09/bigeye-tuna-thunnus-obesus.html" target="_blank">tuna</a>, <a href="http://identifyfish.blogspot.com/2010/09/white-seabass-atractoscion-nobilis.html" target="_blank">seabass</a>, and perch. <br />
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Teleostei also includes unusual fish like the <a href="http://identifyfish.blogspot.com/2010/09/ocean-sunfish-mola-mola.html" target="_blank">mola</a>, which floats near the surface of the ocean in warm currents; the angler fish, which lives on the seafloor and lures its prey using a worm-shaped appendage; and the football fish, which permanently fuses with its mate.<br />
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Movement Many teleost fish have bodies that are shaped to allow them to move easily through water. In particular, fast or constantly swimming fish have body shapes that minimize drag, or resistance to movement. The less surface area comes into contact with water in the forward direction, the less drag the fish will have. <br />
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A torpedo shape, with a body that tapers towards the rear, is one of the most effective shapes for minimizing drag, and many fast-swimming fish have this sort of shape. An example of a fish with a shape that minimizes drag is the swordfish, which can reach speeds up to 75 miles per hour (120 kilometers per hour) in short bursts.<br />
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Some fish, like <a href="http://identifyfish.blogspot.com/2010/10/snake-eels.html" target="_blank">eels</a>, wave their entire bodies back and forth in an “S” shape to move through the water. This is not a very efficient way of swimming as it requires a lot of energy and it increases the surface that confronts the water as the fish swims forward. <br />
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More advanced swimmers have a stiff body, with a tail that bends back and forth behind the fish. This allows the fish to conserve energy because it only moves its tail, not its entire body. It also minimizes the area that confronts the water to the head of the fish.<br />
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Water and gas balance Just like humans, metabolism (the process of cells burning food to produce energy) in fish requires oxygen and produces carbon dioxide as a waste product. Fish breathe through gills, which are found underneath flaps on both sides of the head. <br />
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Water containing dissolved oxygen is brought in through the mouth and pumped over the gills. The gills are packed with blood vessels that absorb the oxygen from the water and produce the carbon dioxide waste that is generated within the fish.<br />
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The body fluids of saltwater teleost fish are about one-third as salty as ocean water. Another way of thinking about this is that the concentration of water inside these fish is greater than the concentration of water in the ocean. Because of osmosis (the passage of a liquid from a weak solution to a more concentrate solution), the water from the inside of the fish is constantly diffusing (moving outward) from the fish. <br />
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As a result, saltwater fish must regularly drink seawater to replenish the water that is lost by osmosis. The fish have special salt glands in their gills that remove the excess salt that comes inside the fish with the seawater.<br />
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Lateral line Teleost fish have developed an interesting sensory organ that helps to sense vibrations in the water. Along both sides of most teleost fish is a long row of canals (tubes) that are packed with nerve cells. These nerves detect movements of currents, changes in water pressure, and even noises.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-38393152366322687712013-07-15T20:20:00.000+07:002017-02-14T15:29:34.791+07:00Geology of the Ocean Floor<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://lifeofplant.blogspot.com/2011/12/types-of-biomes.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Geology of the Ocean Floor" border="0" src="https://4.bp.blogspot.com/-32rs-gXANAQ/UePys24rMYI/AAAAAAAAFLk/HnJmmvD4URE/s1600/Geology-Floor.jpg" title="Geology of the Ocean Floor" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Geology of the Ocean Floor</td></tr>
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Geology is the study of the solid Earth and its history. Marine geology is the study of the solid rock and basins that contain the oceans. The rocks and sediments (particles of sand, gravel, and silt) that lie beneath the oceans contain a record book of Earth’s past. <br />
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Topographic features (the physical features of the surface of Earth) and geologic processes in the ocean basins hold the keys to plate tectonics, a fundamental theory of geology that explains the movement of the continents and seafloor over time. (A plate is a rigid layer of Earth’s crust and tectonics is the large scale movements of the crust.) Only when scientists began to successfully probe the secrets of the seafloor in the mid-twentieth century did they begin to understand the <a href="http://trytostayhealthy.blogspot.com/2010/12/vitamin-b-complex.html" target="_blank">complex</a> workings of the solid Earth.<br />
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If marine geology is the study of the <a href="http://be-eco-friendly.blogspot.com/2010/10/ocean-dumping.html" target="_blank">ocean</a> soup bowl, then oceanography is the study of the broth, and marine biology is the study of the vegetables and meat in the broth. These three branches of ocean science are closely linked. The mountains and valleys of the seafloor, together with the continental margins (edges), act to guide ocean currents (a steady flow of water in a prevailing direction) that in turn regulate global climate. <br />
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<td align="center"><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/gp/product/1570914036/ref=as_li_ss_il?ie=UTF8&linkCode=li3&tag=waterabout-20&linkId=59192d2016a1d4595ec91a1d9d827ae0" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=1570914036&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=1570914036" style="border: none !important; margin: 0px !important;" width="1" /></span><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/Sea-Change-Message-Sylvia-Earle/dp/0449910652/ref=as_li_ss_il?_encoding=UTF8&psc=1&refRID=7CJPP0ABZ8F32C8MDNGB&linkCode=li3&tag=waterabout-20&linkId=f362653019273a8943a86bed2e3960f3" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=0449910652&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=0449910652" style="border: none !important; margin: 0px !important;" width="1" /></span></td>
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Moving water shapes the seafloor by eroding (wearing away) and depositing sediments (particles of gravel, sand, and silt). The seafloor provides shelter and nutrients (food) for marine (ocean) plants and animals, and living organisms play a role in shaping the seafloor. <br />
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They burrow (dig holes and tunnels), build shelters, and consume nutrients during their lifetimes, and their remains form layers of sediment on the seafloor. Practical knowledge of seafloor topography (called bathymetry) and marine geology is essential for human navigators, coastal and marine engineers, naval tacticians, as well as petroleum (oil and gas) and mineral prospectors.<br />
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<b>Depth and shape of the seafloor</b><br />
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Bathymetry beyond shallow coastal waters was a complete mystery until the middle of the 1800s. Until then, navigators used relatively short ropes and chains to make water depth measurements, called soundings, and to construct charts of shallow coastal waters where seafloor topography is a shipping hazard. <br />
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By the 1860s, however, advances in science had raised a number of intriguing questions about the nature of the deep ocean floor. Royal Society of London naturalists aboard the ship Challenger used newly developed steel cables to take more than 500 soundings and to dredge 133 rock and sediment samples from the deep ocean during their expedition from 1872 to 1876.<br />
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The Challenger scientists discovered that the oceans are very deep. They took their deepest sounding in an ocean trench near the Mariana Islands in the western Pacific Ocean. Today, it is known that Earth’s lowest point, the Challenger Deep in the Mariana Trench, is 36,201 feet (11,033 meters) below sea level. <br />
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In comparison, Earth’s highest point, the peak of Mt. Everest in the Himalayan Mountains, is a mere 29,035 feet (8,850 meters) above sea level! The average water depth in the main oceans is 12,200 feet (3,729 meters), deeper than the highest points in 38 of the 50 states of the union. Dredge samples from the Challenger expedition showed that ocean rocks and sediments are fundamentally different from those found on land.<br />
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In spite of the tantalizing clues turned up by nineteenth century British scientists, a full picture of the ocean basins did not come into focus until the late 1950s. In the early twentieth century, the spirit of scientific inquiry during the Challenger era was replaced by more practical reasons to map the seafloor— naval warfare during the first and second world wars. A new technique, called sonar echosounding, replaced expensive, relatively inaccurate wire soundings. An echosounder works by bouncing a sound wave off the seafloor. <br />
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Sound travels at a constant velocity (speed) in water, so the time it takes for the sound to travel through the water and echo back to the ship gives the distance to the seafloor. The faster the sound returns, the shallower the water. American ships carrying troops and supplies to Europe and Asia carried echosounders that recorded the water depths along their routes.<br />
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Civilian scientists were intrigued by what they saw on the wartime bathymetric profiles, and they set out to survey the seafloor using the new, accurate, inexpensive echosounders. The first complete maps of the Pacific, Atlantic, Indian, and Arctic Ocean basins were compiled by Columbia University marine geologists Bruce Heezen and Marie Tharp and published by the <a href="http://amzn.to/2klYjzT" rel="nofollow" target="_blank">National Geographic Society</a> in the mid-1950s. <br />
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The features that were clearly visible on these bathymetric maps, globe-encircling chains of underwater volcanoes and deep ocean trenches, led to a revolution in marine geology and the theory of plate tectonics during the 1960s and 1970s.<br />
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<b>Seafloor features</b><br />
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A bathymetric profile (cross-section) of a major ocean basin like the Pacific Ocean shows the typical features of the seafloor: continental shelf, continental slope and rise, mid-oceanic ridge, ocean trench, and abyssal plain.<br />
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<li><a href="http://amzn.to/2km16t4" rel="nofollow" target="_blank"><b>Continental shelf</b></a>: Continental shelves are the relatively shallow, submerged margins of the continents. Some shelves, like the east coasts of North and South America, are very wide. Others, like the west coasts of North and South America, are very narrow. Over geologic time, the shorelines on continental shelves retreat and advance as the ice in the North and South Poles grow and shrink and global sea-level rises and falls.</li>
<li><b>Continental slope and rise</b>: The continental slope is the steep transition from the continental shelf to the floor of the abyssal (deep) ocean. The slope is cut by huge canyons that carry underwater landslides, called turbidite flows, downslope at speeds of up to 40 miles (64 kilometers) per hour. The continental rise is the deposit of sediments at the base of the continental slope.</li>
<li><a href="http://amzn.to/2lK1wFU" rel="nofollow" target="_blank"><b>Mid-oceanic ridge</b></a>: The most striking feature of Heezen and Tharp’s bathymetric map was the mid-oceanic ridge system, a continuous chain of low, symmetrical volcanoes that extends through all the ocean basins. A mid-oceanic ridge, like the Mid-Atlantic Ridge between South America and Africa, is a broad uplift with a small valley at its axis (center). Mild volcanic eruptions fill the ridge axis valley with molten lava that cools to become new seafloor. The ocean basins on either side of a mid-oceanic ridge are symmetrical mirror images that are moving away from the ridge axis over time. </li>
<li><b>Ocean trenches</b>: Trenches are deep, arc-shaped submarine valleys along the edges of the ocean basins. They are the deepest parts of Earth’s oceans. Scientists now know that the moving seafloor is recycled into Earth’s interior at trenches, a process called subduction. Chains of large volcanoes, called arc volcanoes, form on the outer edges of trenches. The Andes Mountains of South America and the islands of Japan are examples of arc volcanoes. Friction between rocks during subduction also causes very large earthquakes. The geologically active subduction zones that surround the Pacific Ocean are called the “ring of fire.” </li>
<li><a href="http://amzn.to/2laSqVQ" rel="nofollow" target="_blank"><b>Abyssal plains</b></a>: The abyssal plains are vast, flat areas of the deep-ocean floor. In some places, small repeating sets of sharp-peaked ridges, called abyssal hills, interrupt the nearly featureless abyssal seafloor. Cross-sections through the seafloor show that abyssal hills are the tips of tilted blocks of rock beneath a blanket of deep-ocean sediment.</li>
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<b>Ocean rocks and sediments</b><br />
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The solid rock, called the basement, that acts as the floor of the deep ocean is different from that of the continents. Earth’s rocky outer crust comes in two varieties, continental and oceanic, that have very different properties and compositions. <br />
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Ocean crust is denser, thinner, darker-colored, and contains more of the chemical elements iron and magnesium than continental crust. The basement of the ocean basins is mostly made of black, volcanic rock called basalt. Mid-oceanic ridge volcanoes produce basalt. <br />
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The centers of the continents are composed mainly of coarse-grained, light-colored rocks like granite. The blanket of sediment that covers the floors of the abyssal plains is called pelagic ooze. Oozes form by the slow, steady accumulation of silica- and calcium-rich remains of microscopic animals and plants that sink to the deep seafloor.<br />
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The boundary between deep ocean rock and continental land rock lies beneath massive fans of sediment that form the continental margins. Continental margins, including the continental shelf and slope, are composed of thick stacks of layered sediment that rivers and glaciers have carried from the continental interior. <br />
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Some shelves, called carbonate shelves, are composed of the calcium carbonate shells and skeletons of organisms like corals and mollusks. Along many continental margins, continental sediments gradually give way to pelagic oozes at the toe of the continental rise.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-57854315875136758512013-07-15T18:51:00.006+07:002017-02-18T23:00:44.338+07:00Islands<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2015/03/yellow-dock.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="An island" border="0" src="https://1.bp.blogspot.com/-HElMNXoT0-k/WKhvPV-sUVI/AAAAAAAAdaM/Av2q5kFXBgAhf6sHY_s0ENopVMbBIp8_wCLcB/s1600/island.jpg" title="An island" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">An island</td></tr>
</tbody></table>
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Islands are land areas smaller than a continent that are completely surrounded by water. Islands range in size from islets (small islands) barely exposed at high tide, to vast landmasses almost the size of continents. Islands exist in all the ocean basins (the deep part of the ocean floor), along coastlines, and in freshwater lakes and rivers. <br />
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Islands come in many sizes and shapes, but they all share the same defining characteristics. There are more similarities than differences between a huge arctic island like Greenland and a small tropical one like Guam.<br />
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Islands are isolated. The water around them controls their climate and weather. The British Isles, which include Great Britain and Ireland, have a mild climate for their northern location because they lie in the path of the warm Gulf Stream current (a current is a steady flow of water on a prevailing direction). <br />
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The Galapagos Islands, located on the equator in the Pacific Ocean, are kept surprisingly cool due to the rising of cold water from the deep ocean. Islands have limited areas for catching rainwater or snow, and fresh water is generally scarce, particularly on small islands in arid (extremely dry) areas. <br />
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The majority of islands are remote and difficult for land plants and animals to reach. They often support unique ecosystems (groups of organisms that live in a particular environment) that have evolved (changed over time) with little influence from surrounding areas.<br />
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Geologic (natural Earth processes) activities form islands through various ways, including by raising a piece of seafloor above the water surface, or by separating an area of land from the edge of a continent. Volcanoes and corals (small crustacean animals that live in shallow parts of the ocean, building coral reefs with their shells) both construct mounds on the seafloor that can become exposed islands. Chunks of land can be separated from continents. <br />
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When the global sea level rises or falls because of melting and freezing of ice on the North and South Poles, islands can be exposed or submerged. Islands also sink below sea level under the weight of volcanic lava flows or ice, and rise when the rock is naturally worn away from their surfaces. Many islands form by a combination of these geologic processes.<br />
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<b>Volcanic islands</b><br />
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<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/05/south-beach-diet.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Volcanic islands" border="0" src="https://2.bp.blogspot.com/-NmH3LAxAkTM/UePStfVn_KI/AAAAAAAAFLU/WnfGQC_keaY/s1600/Volcanic-islands.jpg" title="Volcanic islands" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Volcanic islands</td></tr>
</tbody></table>
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Many islands are the exposed peaks of active and inactive seafloor volcanoes. An active volcano is one that has erupted in the past and is likely to do so again; an inactive volcano is no longer likely to erupt. Chains of volcanic islands, including the Aleutian Islands, Japan, the Philippines, and the Solomon Islands form the “ring of fire” that surrounds the Pacific Ocean. <br />
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These island chains, called volcanic arcs, lie along plate tectonic boundaries, where one massive plate of Earth’s outer layer is sinking beneath a second plate, in a process called subduction. (Plate tectonics is the theory that Earth’s rocky outer layer is broken into pieces, or plates, that move over time.) The islands of Indonesia and Borneo lie over a subduction zone in the northwestern Indian Ocean. Cuba, Hispanola, Puerto Rico, and the Lesser Antilles are volcanic arcs in the Caribbean Sea.<br />
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Other types of volcanoes also build islands and seamounts. (A seamount is an underwater mountain whose peak does not extend above the water surface. Most seamounts are volcanoes that never grew tall enough to become exposed islands, but some are former islands that have been submerged by rising sealevel or their own sinking.) <br />
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Sicily in the Mediterranean Sea, Catalina Island off southern California, and the remote Kerguelan Islands in the southern Indian Ocean are also volcanic islands. Some islands are created from hot spot volcanoes. A hot spot is a stationary heat source under a moving tectonic plate. As the plate moves over the hot spot, a line of volcanoes forms above it. The Hawaiian Islands, Iceland, and more than six hundred small islands in the southwest Pacific Ocean are hot spot volcanoes.<br />
<b><br />
</b> <b>Coastal islands</b><br />
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Erosion (wearing away of material by natural forces) and deposition by nearshore currents and waves shape sediment (sand, gravel, and silt) into islands along coastlines. These processes can form barrier islands, which are long, narrow coastal islands built up parallel to the mainland. Barrier island chains border the edges of continents that receive large amounts of sediment from rivers. <br />
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In the Gulf of Mexico, a strong current has built a continuous chain of barrier islands along the coasts of Texas and northern Mexico by dragging sediment away from the Mississippi River Delta. Tides cut narrow strips of water in the land that separate the sandy barrier strip into islands and carry water into the lagoons (a shallow area of water separated from the ocean by a coral reef or sandbar) between the islands and the mainland. <br />
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Barrier islands like North Carolina’s Outer Banks and South Padre Island in Texas are essentially large sandbars (long strips of sand) that are constantly being reshaped by currents, waves and winds. A large hurricane can completely destroy a barrier island—houses and all—and reshape the sediment into a new island within a few days.<br />
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Not all barrier islands and coastal islands are made of sand. The Florida Keys and barrier islands of northeast Australia are reefs that fringe continental shelves (the edge of land that slopes into the sea) away from major rivers where corals grow in clear waters. <br />
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Long Island, Nantucket, and the other islands off southern New England are huge piles of rock fragments and boulders left by glaciers (large masses of moving ice) that retreated at the end of the last ice age about twenty thousand years ago. <br />
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Some coastlines, like those of Maine, northern California, and Norway are rising from the ocean because of shifting tectonic plates on Earth. Islands off these rising coasts are fragments of sea cliffs and rock that resisted erosion toward the mainland.<br />
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<b>Big islands: continental fragments</b><br />
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The movement of tectonic plates breaks the continents into pieces that move across the Earth surface. Many of Earth’s largest islands are blocks of continental crust that split from the main continents. Madagascar, for example, is a large island in the Indian Ocean that separated from the east coast of Africa. Greenland, New Guinea, and Tasmania are also broken continental blocks. India was a very large island until it collided with Asia about forty million years ago.<br />
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<b>Carbonate Islands</b><br />
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Some islands were at least partially constructed by animals. Many marine organisms including corals, mollusks, and gastropods have skeletons and shells composed of a mineral called calcium carbonate. Limestones and other rocks that form from the remains of these animals are called carbonates. The soft, white beaches of some of the world’s most beautiful islands— Tahiti, Hawaii, the Bahamas, Bermuda, and Bali to name a few—are composed of the carbonate remains of lagoon and reef species. <br />
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Corals are carbonate organisms that build elaborate community structures, called reefs, up from the seafloor. A reef is like an apartment building where each resident builds his own unit. When an individual animals dies, their “apartment” is vacant but still standing, and living corals continue to build the reef upward.<br />
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Carbonate species generally require clear, shallow water to thrive. Coastal carbonate islands, like the Florida Keys, only develop away from river deltas (where rivers meet the sea) where the water is too muddy. Carbonate islands away from coastlines usually have a volcanic or continental structure that provides an area of shallow water for light-loving species. <br />
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The islands of the Bahamas, for example, are the exposed spines of coral reefs that cover a large block of seafloor that was uplifted by plate tectonic forces about 200 million years ago. The Bahamian platform is sinking under the weight of its surfacing limestone layers, but the corals built the reefs up to the sunlight. <br />
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Volcanic islands like Hawaii and Tahiti are typically surrounded by a ring of reefs and a shallow lagoon that host numerous carbonate species. This explains, among other things, how islands of black volcanic rock can have white beaches.<br />
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<b>Island life</b><br />
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Islands are remote. Island plants grew from seeds carried by birds. Some animals walked to islands on exposed land bridges when the sea level was lower during the ice ages, and others rode away from their home continent on a moving chunk of land. However they first arrived, island plants and animals live in closed ecosystems where they interact only with each other. (Some island ecosystems are, of course, more closed than others. <br />
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The difficulties of reaching a barrier island across a lagoon are much less than those of reaching a volcanic island at the center of a huge ocean basin.) Throughout most of Earth’s history, plants and animals that lived on islands are descendants of organisms that swam, floated, or rode there in the past. Today, humans sail, fly, and take man-made bridges to almost all of Earth’s islands, and they bring plants and animals with them.<br />
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Islands often are homes to extremely rare species that are unique to their island or group of islands. Charles Darwin’s (1809–1882) observations of the rare species of the Galapagos Islands inspired his theory of evolution in 1835. He theorized that new species evolve by combinations between individuals with different traits. <br />
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Organisms with the traits best suited to its environment will flourish and reproduce, causing these traits to be continuously passed to offspring. Individuals with traits less suited to their environment will not survive and eventually die out. <br />
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On islands, the number of individuals and species is limited and changes happen more rapidly. Furthermore, because new types of species arrive infrequently, the species that evolve on an island can be totally unique. The Galapagos Islands are home to Earth’s only swimming iguanas as well as huge tortoises that can live for two hundred years.<br />
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Island organisms also evolve to prey on and protect themselves from only the plants and animals on their island. They have no defense mechanisms from non-native predators and little immunity to foreign diseases. When species arrive from afar, island species can suffer. Humans have been particularly destructive to island species because they are predators themselves, and they import many non-native plants, animals, and diseases. <br />
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For example, humans brought snakes to Pacific Islands like Guam and Hawaii that decimated the endemic (native) birds and mammals. Humans then imported mongooses to kill the snakes, and the mongooses proceeded to kill not only snakes, but also a large number of the remaining island species. Today, many island governments and conservation groups are attempting to restore endangered island ecosystems.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-34241419643266556372013-07-15T17:12:00.000+07:002017-02-22T05:12:53.092+07:00Kelp and Seaweed<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/05/soy-protein.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Seaweed" border="0" src="https://1.bp.blogspot.com/-fIXxWf5gs-4/UeO5wXcfxlI/AAAAAAAAFKU/nLdb5oowQLY/s1600/Seaweed.jpg" title="Seaweed" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Seaweed</td></tr>
</tbody></table>
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From the tiniest of bacteria to the massive <a href="http://be-eco-friendly.blogspot.com/2011/03/blue-whale.html" target="_blank">blue whale</a>, the world’s oceans and freshwater support a tremendous variety of life. Often, a beachcomber will find rubbery plants washed up on the shoreline. These exotic-looking plants are seaweed. A dive below the surface of coastal waters in some areas of the world, such as California, reveals a world of towering plants that sway gently in the ocean current. These giants are one form of seaweed called kelp.<br />
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Kelp make up only about 10% of all the known seaweed species. The many varieties of seaweed present in the world’s fresh- and saltwater provide a habitat and even a food source for creatures. Humans benefit from seaweed as well. For thousands of years in Far East countries like Japan, seaweed has been an important part of the diet, in the form of soup stock, seasoning, and as an integral part of sushi. In addition, seaweed is useful in the laboratory. The artificial <a href="http://lifeofplant.blogspot.com/2011/03/growth-and-growth-control.html" target="_blank">growth</a> surfaces used to raise bacteria rely on a seaweed component as a thickening agent, similar to that found in gelatin.<br />
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<b>Characteristics of seaweed</b><br />
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The leafy-looking seaweed that grows in ocean waters is a type of <a href="http://lifeofplant.blogspot.com/2011/12/algae.html" target="_blank">algae</a>. Other forms of seaweed look grass-like or feathery. Algae are plants; that is, they contain the chemical chlorophyll that converts energy from the Sun into food substances that the plant uses to grow. Algae range in size from microscopic single cells (the fundamental unit of all living things) to huge numbers of cells assembled together to form a much bigger organism. Seaweed is the large collection of algae cells, or macroalgae.<br />
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The many types of seaweed come in all shapes, sizes, and colors. Depending on the <a href="http://watersome.blogspot.com/2011/11/species-introduction.html" target="_blank">species</a>, shapes range from the mighty tree-like kelp to the smaller and more delicate leafy or ribbonlike seaweed varieties. Most types of seaweed are found in shallow water, from just a foot or so to depths of 100 to 200 feet below the water’s surface, as it needs sunlight for growth. <br />
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Also, most seaweed is found where there are rocks, as the seaweed clings onto the rock at one end using a structure called a holdfast. Some seaweed can attach to the sandy ocean bottom using a specialized structure that appears similar to the <a href="http://lifeofplant.blogspot.com/2011/01/roots.html" target="_blank">roots</a> of plants that grow on land.<br />
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Like plants, seaweed can convert the energy from sunlight into the compounds needed for its growth. In order words, seaweed is a photosynthetic organism. Some seaweed contains the light-absorbing compound chorophyll, which gives seaweed its green color. Other species of seaweed contain different light-absorbing chemicals that are colored red, brown, blue, or gold.<br />
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While similar to land-bound plants in its light-absorbing ability, seaweed is distinct from its land cousins in other ways. It can contain a holdfast, a part that anchors it to the seafloor. Many types of seaweed also have hollow, gas-filled structures called floats that help buoy the leaves up nearer to the sunlight.<br />
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<b>The three categories of seaweed</b><br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://lifeofplant.blogspot.com/2011/01/red-algae.html" imageanchor="1" rel="nofollow" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;" target="_blank"><img alt="red algae" border="0" height="320" src="https://4.bp.blogspot.com/-7rbi6PBQs3U/UePHkiz--4I/AAAAAAAAFKk/d6sAScKz_54/s320/red-algae.jpg" title="red algae" width="222" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">red algae</td></tr>
</tbody></table>
Seaweed is often grouped into three categories based on its color. These groups are the brown, green, and red algae. Brown algae range in size from forms that are a few inches (centimeters) in size to the giant kelps that can reach over 150 feet (46 meters) long. <br />
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This type of seaweed lives only in salt water, and cannot grow in waters where the temperature varies much. <a href="http://lifeofplant.blogspot.com/2011/10/brown-algae.html" target="_blank">Brown algae</a> is found in waters that stay cold all year, such as the coastal waters of Alaska, or in tropical waters that stay warm all the time.<br />
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The chemicals that make up brown seaweed are useful in the manufacturing of cosmetics and some medicines. For example, kelp can be used in medicine to treat high blood pressure, thyroid problems, and even arthritis. Seaweed is also a rich source of such minerals as iodine, zinc, copper, <a href="http://trytostayhealthy.blogspot.com/2011/01/sodium.html" target="_blank">sodium</a>, calcium, and magnesium, which are important in a healthy diet. <br />
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Additionally, brown seaweed has been an important part of the Japanese diet for centuries; it is used in soups, as an additive to change the taste of other foods, and as a wrap for the raw fish and rice combinations known as sushi.<br />
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The <a href="http://lifeofplant.blogspot.com/2011/01/red-algae.html" target="_blank">red algae</a> group dominates in ecosystems such as coastal regions of California, where they can comprise 70% of all the seaweed species present. The group contains about 3,800 different species of seaweed. Because they can absorb even tiny amounts of sunlight, red algae can live deeper in the water than other kinds of seaweed. Many red algae can live at depths of 150 to 200 feet (46 to 61 meters) below the ocean surface, and some species have been found growing even 600 feet (183 meters) below the surface of the ocean. <br />
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At these depths, the ocean waters are calmer, and the red algae that live there tend to have a more delicate structure. These algae are more easily broken than seaweed that grows in the churning waters nearer to the surface. A component of red algae is also used to make the solid food (agar) that is used in laboratories to grow many types of bacteria.<br />
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Green seaweed can be found in both freshwater and the ocean. These types of seaweed feed on water that contains chemicals such as nitrogen and phosphorus that flow into the water from farmer’s fields, or that are in sewage. When some types of <a href="http://lifeofplant.blogspot.com/2011/03/green-algae.html" target="_blank">green algae</a> are present in high concentrations, this may indicate that the water is polluted with too many of these chemicals.<br />
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<b>Kelp</b><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/06/pyridoxine-vitamin-b6.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Kelp" border="0" src="https://3.bp.blogspot.com/-VI2Uvp56Vbg/WKy6nJXwOqI/AAAAAAAAde0/QtSM9kkwiCU62bEDx9LPSdlEbw6XpF4DwCLcB/s1600/kelp.jpg" title="Kelp" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Kelp</td></tr>
</tbody></table>
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Kelp are a type of brown seaweed that often appear as big leaves swaying in the underwater current. Some types of kelp can grow to be almost 100 feet (30 meters) long, and can form an underwater forest. <a href="http://trytostayhealthy.blogspot.com/2011/06/kelp.html" target="_blank">Kelp</a> are important to life in the sea. <br />
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The thick masses of kelp that grow off the coasts of New York, California, Australia, the Arctic, and the Antarctic are home to a variety of creatures including lobsters, snails, octopuses, seahorses, starfish, fish, and seals. These sea creatures use the seaweed forests as a protective haven as well as a source of food. Thus, kelp is important in establishing and sustaining the complex ecosystems that can form.<br />
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A kelp plant can grow to be dozens of feet (meters) long and grow quickly. It is anchored to the bottom of fairly shallow waters by means of a holdfast and reaches up toward the surface, forming an underwater forest. The leaf-like structures (fronds) that are near the surface have pockets of air built into them, which act as balloons to hold the leaves nearer to the surface where they can capture the Sun’s energy.<br />
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The material that makes up kelp is also part of peoples’ everyday lives. Kelp helps thicken ice cream and jelly, and provides the smooth texture present in some frozen drinks.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-17934956258553906752013-07-15T14:55:00.002+07:002017-02-14T16:14:32.690+07:00Layers of the Ocean<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://lifeofplant.blogspot.com/2011/03/mediterranean-scrub.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Layers of the Ocean" border="0" src="https://3.bp.blogspot.com/-0pJBy-l2Wrg/UeOhlF3hX3I/AAAAAAAAFJk/0691R-3s7u8/s1600/Layers-Ocean.gif" title="Layers of the Ocean" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Layers of the Ocean</td></tr>
</tbody></table>
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Oceanographers (scientists who study the oceans) often divide the ocean into horizontal layers. They use the physical characteristics of the water such as temperature, density, and the amount of light at different depths to classify these layers. The most important factor is the density of the water, which is determined by the combination of salinity (the amount of salt in the water) and temperature. <br />
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All ocean water is salty, but some contains more salt than others. The water that is saltier is heavier and sinks, while the water that is less salty is lighter and floats. Similarly, warmer water is lighter than colder water, so it floats on top of colder water.<br />
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Oceanographers generally categorize the ocean into four layers: the epipelagic zone, the mesopelagic zone, the bathypelagic zone, and the abyssopelagic zone. The word “pelagic” refers to the open ocean, away from the coast. The prefix epi means “surface”; the prefix meso means “middle”; the prefix bathy means “deep”; and the prefix abysso means “without bottom.” In addition, the transition zone between the epipelagic and the mesopelagic is often called the thermocline.<br />
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<b>Epipelagic zone</b><br />
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The epipelagic zone refers to the surface of the ocean where light penetrates. This layer is also called the photic zone, referring to the light that is found at these depths. Light is extremely important in the ocean. Just like plants on land, phytoplankton (free-floating plants, generally microscopic) require light to grow. <br />
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Phytoplankton are the base of the food web (the network of feeding relationships in an ecosystem) in the ocean; they produce food by converting the energy from the Sun into energy they need to live and grow. When phytoplankton are eaten by zooplankton (free-floating animals) and fish, this energy is converted into the materials in their bodies. <br />
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This transfer of energy continues as each predator (an animal that hunts, kills, and eats other animals) eats its prey (animals that are hunted and eaten by other animals), but it all begins with the energy from the Sun.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2015/02/yerba-santa.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Epipelagic zone" border="0" src="https://1.bp.blogspot.com/-L2qQ4-jZdSY/UeOmz9DmjnI/AAAAAAAAFJ0/9HhZhYu8Qd8/s1600/Epipelagic-zone.jpg" title="Epipelagic zone" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Epipelagic zone</td></tr>
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Sometimes the photic zone is referred to as the surface mixed layer. This layer is in contact with the wind and air above the ocean. The wind acts as a mixer, moving the water up and down throughout the top layer of the ocean. As a result, all of the water in the surface mixed layer has the same density. Because this water is often in contact with the air, it contains many of the gases required for life, such as oxygen and carbon dioxide.<br />
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The epipelagic zone extends about 500 feet (150 meters) into the ocean, although this varies depending on location. Only about 2% of the total volume of the ocean falls in the epipelagic zone.<br />
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The thermocline Just below the surface mixed layer is a layer of water where the temperature and density change very quickly. This layer is called the thermocline. In warm tropical waters, the thermocline is very abrupt, while in cold polar waters the thermocline is often rather gentle. <br />
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Below the thermocline, the temperature is always about 40°F (5°C). The thermocline acts as a density barrier between the surface, where there is light and phytoplankton growth, and the deeper layers of the ocean, where food is often scarce.<br />
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<b>Mesopelagic zone</b><br />
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The mesopelagic zone extends from about 500 feet (150 meters) to about 3,250 feet (1,000 meters) below the surface. It is often referred to as the “twilight zone” because it is between the epipelagic zone where there is light and the deep ocean where light is absent. <br />
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The majority of light in this part of the ocean comes from bioluminescence, light that is generated by chemical reactions in bacteria, animals, and plants. Because the epipelagic zone is where phytoplankton grow and where zooplankton and fish feed on phytoplankton, some animals that live in the mesopelagic zone migrate upwards at night to feed. <br />
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Other animals in the mesopelagic zone rely on food that falls through the thermocline into the mesopelagic zone. Still others have developed special adaptations to prey on the animals that live within the mesopelagic zone. Since food is rather scarce in this zone, predators often have sharp teeth and expandable stomachs to take advantage of anything they encounter, even if it is bigger than they are.<br />
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<b>Bathypelagic zone</b><br />
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<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2015/04/vomiting.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Bathypelagic zone" border="0" src="https://1.bp.blogspot.com/-I-JmaLLq7TU/UeOqOFWVmlI/AAAAAAAAFKE/Cre78PRCiCo/s1600/Bathypelagic-zone.jpg" title="Bathypelagic zone" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Bathypelagic zone</td></tr>
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The bathypelagic zone is the part of the ocean between about 3,250 feet (1,000 meters) and 13,000 feet (4,000 meters) below the surface of the ocean. Light is almost non-existent in this part of the ocean. What little light there is, is generated from bioluminescence from animals and bacteria. The pressure is also extremely great in this part of the ocean. <br />
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However, marine life still exists here. Fish, jellyfish, mollusks, and crustaceans (aquatic animals having no backbone with jointed legs and a hard shell) all have representatives that live at these extreme depths. Most of these animals are either black or red. Red appears black at these depths, because the only wavelengths of light (wave patterns of light that are perceived by the eye as colors) available are blue light from bioluminescence.<br />
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<b>Abyssopelagic zone</b><br />
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The abyssopelagic zone extends from 13,000 feet (4,000 meters) below the surface to the seafloor. In this zone, the waters are nearly freezing and the pressures are immense. Nonetheless, there are some animals that live in this very deep part of the ocean. Squid and jellyfish can be found swimming through the waters in the deep ocean. <br />
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Often, they have little color but they do have special organs that can produce light. This bioluminescence is used to attract prey and scare away predators. Several kinds of echinoderms (spiny-skinned animals including starfish and sea urchins) are relatively common in the abyssopelagic zone. The basket star has long arms that it waves above the seafloor in order to catch prey. <br />
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The sea pig is a kind of sea cucumber that digs holes or tunnels in the mud, digesting dead animals and bacteria. Another sea cucumber called the flying cucumber has flaps like wings to fly through the deep ocean. Crustaceans can also be found in the abyssopelagic zone. Sea spiders and isopods (of the shrimp family) are often found in these deep regions.<br />
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Very deep trenches (narrow depressions or cracks in the sea floor) can extend down to 35,750 feet (11,000 meters) in some parts of the ocean. Trenches are the deepest parts of the ocean and are classified by some oceanographers as the hadal zone.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-46506862052812478652013-07-15T05:54:00.003+07:002017-02-14T16:39:19.416+07:00Marine Invertebrates<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2011/11/agricultural-water-use.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Marine Invertebrates" border="0" src="https://3.bp.blogspot.com/-80pCFMq5ucA/UeMdgi9fnrI/AAAAAAAAFIU/TYFGb14IG3o/s1600/Marine-Invertebrates.jpg" title="Marine Invertebrates" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Marine Invertebrates</td></tr>
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Invertebrates are animals that do not have a bony internal skeleton, although many do have hard outer coverings that provide structure and protection. More than 90% of all animals are invertebrates and they are classified into at least 33 major groups, or phyla. Nearly every phylum of invertebrates has members that live in the oceans. <br />
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Six phyla of invertebrates that are commonly found in the oceans are: Porifera (sponges); Cnidaria (corals, jellyfish, and sea anemones); Annelida (segmented worms); Molluska (snails, clams, mussels, scallops, squid, and octopuses); Arthropoda (crabs, shrimp, barnacles, copepods, and euphausids); and Echinodermata (sea stars, sea urchins, and sea cucumbers). Each phyla is divided into smaller groups called classes, which is then split into families and then species.<br />
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<b>Phylum Porifera</b><br />
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The sponges are the least complex multicellular animals. They generally live attached to a surface and have three basic shapes, encrusting, vase-like, and branching. <b>Sponges</b> live in intertidal (between the tides) zones as well as in the deep ocean. They can be a few inches (centimeters) to 10 feet (3 meters) in diameter. There are nearly 10,000 species of sponges and all but two families are only found in ocean environments.<br />
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The general body of a sponge is a central cavity surrounded by a fleshy body riddled with holes. The cells lining these holes pump water into the central cavity. As the water moves through their bodies, the sponge absorbs nutrients, and filters out particles from the water as their food. The name Porifera means “hole bearer,” reflecting the many holes in the animals’ bodies.<br />
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<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2011/11/aquaculture.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="sponges" border="0" src="https://1.bp.blogspot.com/-wqdkgIClAdk/UeMikwZS61I/AAAAAAAAFIk/P3zFBWqMuXo/s1600/sponges.jpg" title="sponges" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">sponges</td></tr>
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<b>Phylum Cnidaria</b><br />
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The phylum Cnidaria includes jellyfish, sea anemones, and corals. The word Cnidaria comes from the root word knide, which means “nettle.” It refers to the special stinging cells that the animals in this group have for protection and predation (hunting an animal for food). These cells contain coiled threads that are fired at predators and prey. The threads may contain substances that paralyze or sticky substances that entangle their target.<br />
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Cnidarians have two body plans: polyp and medusa. Corals and sea anemones are typical polyps. They are jar-shaped animals with a mouth at the opening of the jar. Tentacles rim the mouth and are used to pull food into the stomach, which is located on the inside of the jar. <b>Sea anemones</b> have a basal disc (tooth-like structure), which is located where the bottom of the jar is, and it is used to burrow (dig a tunnel or hole) into the sand or rocks. <br />
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Corals have a skeleton made of the mineral calcium carbonate, which cements the individual coral polyps together into a colony (group). Jellyfish have a medusa shape, and this can be visualized as a polyp turned upside-down so that it looks like a bell. Jellyfish swim by contracting their bodies and forcing water out of the bell. They have long tentacles (appendages) surrounding their mouths that are used to capture prey.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2011/11/minerals-and-mining.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="sea anemones" border="0" src="https://4.bp.blogspot.com/-pNzageM9960/UeMmPfoN4EI/AAAAAAAAFI0/Nf0aNVWgooo/s1600/sea-anemones.jpg" title="sea anemones" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">sea anemones</td></tr>
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<b>Phylum Annelida</b><br />
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The phylum Annelida includes worms that are segmented, meaning that the body is made up of sections. Each body section may have a specialized purpose, such as reproduction, locomotion, or sensing the environment. These segments are apparent on the outside of the worm’s body and make it look ringed. The word Annelida comes from the word annelus, meaning “ringed.” The most familiar member of Annelida is the earthworm, which is not a marine <a href="http://watersome.blogspot.com/2011/11/species-introduction.html" target="_blank">species</a>.<br />
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The class Polychaeta (meaning “manyfooted”) is the largest class of Annelida, with about 10,000 species, most of which are marine (of the ocean). Almost all of them have paired appendages on their segments that can be used for swimming, burrowing, or walking. <br />
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Polychaetes often have very well developed heads with a variety of sensory organs that detect prey by touch, vision, and smell. They range in appearance from very colorful to very plain-looking. Some swim through the water, others crawl on the sand or rocks, and others live cemented to the seafloor, building and living in tube-like structures. <br />
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<b>Phylum Molluska</b><br />
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The mollusks are an extremely large phylum with over one hundred thousand species, most of which are marine. Most mollusks have a head, a foot, and a body that is covered by a shell-like covering called a mantle. The three most common classes of mollusks are the snails; the clams, oysters, scallops, and mussels; and the squid and <b>octopuses</b>.<br />
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The gastropods are the largest class of mollusks with over eighty thousand species. They include snails, slugs, abalone, and limpets. Most gastropods crawl along the seafloor among rocks, grazing on <a href="http://lifeofplant.blogspot.com/2011/12/algae.html" target="_blank">algae</a> (tiny rootless plants that grow in sunlit waters). <br />
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Some, however, hunt for their food among plankton, which are organisms that drift through the ocean. Other gastropods filter water for food particles. The majority of gastropods live in coiled shells, which provides protection from predators and protection from the force of waves. The shells are also used to protect animals that live in the areas between low and high tides from becoming too dry.<br />
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The bivalves, meaning “two doors,” are mollusks that have two shells like clams, scallops, mussels, and oysters. These animals generally live in sediments (sand, gravel, and silt) on the bottom of the ocean and gather food by filtering particles out of the water. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2011/11/shipping-on-oceans.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="octopus" border="0" src="https://1.bp.blogspot.com/-Z8j5e1ZOoIs/UeMqEy-PUjI/AAAAAAAAFJI/Y44M-5PNrrM/s1600/octopus.jpg" title="octopus" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">octopus</td></tr>
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Many clams are able to burrow into sand or clay. Scallops can swim by forcing water through their shells. Oysters tend to cement themselves to hard surfaces. Mussels produce tough strings called byssal threads that attach their shells to surfaces in wave-swept areas.<br />
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The most complex of the Mollusca phylum are the squid, octopuses, nautiluses, and cuttle fish. Each of these animals has a head that is surrounded by tentacles. They swim through the water using propulsion from their tentacles, much like swimmers kick their legs underwater, and creep along the bottom of the ocean using their tentacles as legs. <br />
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Cuttle fish and squid have a shell like other mollusks, but it has been internalized. In octopi, the shell is completely absent. The members of this class have excellent eyesight and are considered intelligent.<br />
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<b>Phylum Arthropoda</b><br />
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Arthropods are the most numerous invertebrate phylum with over one million species identified. Some scientists expect that there may be as many as ten million arthropods on Earth. All arthropods have a strong external skeleton that protects them from predation and supports their body structures. They have a type of muscle called a striated muscle that allows them to move quickly. They also have legs, antennae, and other appendages that are jointed.<br />
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The phylum Arthropoda has three major divisions or subphyla. The subphylum Crustacea includes about thirty thousand different species, most of which live in the ocean. Crustaceans include many different types of marine animals that are divided into several classes. Brine shrimp, which are important fish food and live in very salty water, belong to the class Branchiopoda. <br />
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The class Maxillopoda includes barnacles and copepods. Barnacles are specialized crustaceans that spend the adult part of their life cemented head-down on hard surfaces like rocks, piers, the bottoms of ships, and even the undersides of whales. <br />
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Their legs have developed into featherlike appendages that they use to generate water currents to bring food particles into their mouth. Copepods are small shrimp-like animals that are extremely important to the planktonic food web, the network of plankton that form the base of the food chain in the oceans. They are the most numerous animals in the ocean, sometimes reaching densities of more than a million per cubic yard (meter).<br />
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The class Malacostraca includes shrimp, lobsters, crabs, and euphausids. There is an enormous amount of diversity among the members of this class, which includes about twenty-five thousand different species. Some malacostracans spend their lives swimming among <a href="http://watersome.blogspot.com/2013/07/plankton.html" target="_blank">plankton</a>, others walk along the ocean floor scavenging for food, while others live in burrows and attack prey that come nearby. Many members of this group live and feed off of fish or even other crustaceans. This class is very important to the economy, both as food for humans and as pets in the aquarium industry.<br />
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<b>Phylum Echinodermata</b><br />
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All of the six thousand members of the phylum Echinodermata are marine. The root word echino means “spiny” and the root word derma means “skin.” The name Echinodermata refers to the bony structures called ossicles found in the skin of these animals. Echinoderms do not have well developed sensory organs or brains. <br />
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They all have a water vascular system that is used to circulate nutrients and gasses through their bodies. All echinoderms share the same general appearance, which is based on five similar sections that radiate out from a central point.<br />
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There are five classes of echinoderms: feather stars, sea stars, brittle stars (sea stars), sea urchins, and sea cucumbers. Brittle stars are fairly uncommon. There are about six hundred species of brittle stars, living mostly in shallow waters.<br />
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Sea stars (commonly known as starfish) use their water vascular system to operate suction cups located on the bottoms of their legs. These suction cups are called tube feet and they are used both for predation and for gas exchange. Sea stars eat by gripping both shells of a clam or mussel with its tube and pulling the prey open. Then it inverts its stomach inside the shells and digests the victim.<br />
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Ophiuroids usually look like a small disc surrounded by five long worm-like arms. They are called brittle stars because when they are attacked, they will simply detach the arm that has been the target. Later, the ophiuroid will regenerate its arm.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2011/11/surface-and-groundwater-use.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="sea cucumbers" border="0" src="https://4.bp.blogspot.com/-2cNXE87nvfI/UeMr9puGdFI/AAAAAAAAFJU/eSH0yDacL5c/s1600/sea-cucumbers.jpg" title="sea cucumbers" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">sea cucumbers</td></tr>
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Sea urchins are usually pin cushion-shaped and covered with sharp spines. These spines are used for locomotion as well as for defense. Between the spines, sea urchins have special appendages called pedicellariae that look like tiny claws. These are used for capturing prey and for cleaning. The mouth of the sea urchin is on its underside and is composed of five tooth-like plates.<br />
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Sea cucumbers live on the sea floor and look like cucumbers with five soft ridges. Many live on coral reefs and are extremely colorful. Sea cucumbers feed by extruding feathery appendages that can capture prey that swim too close. When attacked, many sea cucumbers will suck in water and then use the water pressure to eject their internal organs, including their digestive and respiratory systems. <br />
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The predator becomes confused among all the tissues in the water and may even become entrapped in some of the sticky material. After such an attack, a sea cucumber will regenerate its internal organs over a period of several weeks.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-90252383135764016512013-07-14T23:20:00.003+07:002017-02-26T12:54:54.570+07:00Marine Mammals<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2012/09/climate.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Marine Mammals" border="0" src="https://1.bp.blogspot.com/-rar1nMDZp3k/UeKr_jfEdLI/AAAAAAAAFG0/v7mljqGLlnc/s1600/Marine-Mammals.jpg" title="Marine Mammals" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Marine Mammals</td></tr>
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Mammals are vertebrates (animals with a backbone) that share characteristics of nursing their young with <a href="http://trytostayhealthy.blogspot.com/2010/09/milk.html" target="_blank">milk</a>, breathing air, having hair at some point in their lives, and being warm-blooded. Marine mammals are the species of mammals that depend on the oceans for all or most of their lives. <br />
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There are about 115 different species of marine mammals. Marine mammals vary from the small sea otter to the giant <a href="http://be-eco-friendly.blogspot.com/2011/03/blue-whale.html" target="_blank">blue whale</a>. Some of them live in groups, like dolphins, while others are solitary, like polar bears. All marine mammals share four characteristics:<br />
<ul>
<li>They have a streamlined body shape that makes them excellent swimmers.</li>
<li>They maintain heat in their bodies with layers of fat called blubber.</li>
<li>They have respiratory (breathing) systems that allow them to stay underwater for long periods of time. </li>
<li>They have excretory (waste) systems that allow them to survive without drinking freshwater. Instead they obtain the water they need from the food they eat. </li>
</ul>
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Marine mammals belong to three groups called orders. An order is a classification of a group of organisms, which eventually splits into species. Marine mammals are in the orders Cetecea, Carnivora, and Sirenia.<br />
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<b>Order Cetacea</b><br />
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There are about seventy-seven species of cetaceans, which include whales, dolphins, and porpoises. All of these animals live their entire lives in the water. Cetaceans probably evolved from the hoofed mammals that were similar to horses and sheep. <br />
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Their front legs became fins that are used primarily for steering, and their hind legs became extremely small flippers or flukes (tail fins) so as to streamline the animals for swimming. Cetaceans swim by moving their strong fluke up and down. They are grouped into two categories or suborders: Odontoceti, the toothed whales, and Mysteceti, the baleen whales.<br />
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<b>Suborder Odontoceti</b>. The toothed whales account for about 90% of all cetaceans, including <b>dolphins</b> and porpoises as well as the orca (killer whale) and the sperm whale. Toothed whales hunt for prey, which they capture with their teeth. They also have one external hole called a blowhole for breathing. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/04/relaxation.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Dolphins" border="0" src="https://1.bp.blogspot.com/-t84IeKRSOHk/WKMPdttkptI/AAAAAAAAdVM/fG9b54r0_NkQRPAF6PUsktBeje_zI2DdQCLcB/s1600/dolphins.jpg" title="Dolphins" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dolphins</td></tr>
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The toothed whales have a large brain for their size and are considered to be some of the most intelligent animals. They hunt using sophisticated echolocation, which is the method of detecting objects by listening to the reflected sounds that it calls out.<br />
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<b>Suborder Mysteceti</b>. The baleen whales have no teeth. Instead, they have bristly plates called baleen, which hangs like a curtain from their upper jaws. Baleen is made from a protein similar to that which makes up human fingernails. <br />
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When it is eating, the baleen whale sucks in huge amounts of water and then forces the water out through its baleen, which acts like a sieve. These whales diet primarily on tiny animal <a href="http://watersome.blogspot.com/2013/07/plankton.html" target="_blank">plankton</a>, animals that drift through oceans. Microscopic plankton are concentrated behind the baleen and then swallowed. <br />
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Even though baleen whales feed on some of the smallest animals in the world, baleen whales are some of the largest animals in the world. The <b>blue whale</b>, the fin whale, and the gray whale all weigh more than 2 tons (9 metric tons). Baleen whales are also distinguished from toothed whales because they have two external blowholes instead of one.<br />
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<b>Order Carnivora</b><br />
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The Carnivora include animals that prey on each other (meat-eaters) like dogs, cats, bears, and weasels. There are two suborders of carnivores that have marine representatives: the pinnipeds and the fissipeds.<br />
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Suborder Pinnipedia Pinnipeds include seals, <b>sea lions</b>, fur seals and walruses. They all have flippers that can be used to move around on land as well as on water. Although they swim much more efficiently than they walk on land, they do give birth to their young on land.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/04/tendinitis.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="sea lion" border="0" src="https://2.bp.blogspot.com/-y6ldK_YF-hA/WKMHE6FHqeI/AAAAAAAAdUQ/DTSQ5BQBAmIeSoZ5U_3EtCsDsBtFPJeVgCLcB/s1600/sea-lion.jpg" title="sea lion" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">sea lion</td></tr>
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Seals account for nearly 90% of all pinnipeds. There are nineteen species that live in all of the oceans and even in a few lakes. Most seal species live near Antarctica and in the Arctic Circle. Seals do not have an external ear, although they can hear very well. They propel themselves with their rear flippers and use their front flippers for steering.<br />
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Sea lions and fur seals do have small external ears. Their hind legs are more flexible than those of seals, so they can move around better on land. They propel themselves with their front flippers when swimming.<br />
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Walruses are the largest of the pinnipeds. They do not have an external ear, but they can use their rear flippers for moving on land. The canine teeth (pointed, in the front) of walruses are enlarged into tusks. Walruses swim along the bottom of the ocean using their tusks like runners as they look for clams to eat.<br />
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Suborder Fissipedia The suborder Fissipedia includes cats, dogs, raccoons, and bears, as well as two marine mammals: sea otters and polar bears. Sea otters are about 4 feet (1.2 meters) long, the smallest of the marine mammals. <br />
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Their favorite food is sea urchins, which they eat by lying on their back and smashing them on a stone that is balanced on their chests. Polar bears wander long distances across sheets of floating ice in the Arctic hunting for seals and whales. They can swim between patches of ice using their powerful forepaws like oars.<br />
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<b>Order Sirenia</b><br />
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<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2012/09/global-climate-change.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="manatees" border="0" src="https://2.bp.blogspot.com/-TvUsIf3Gjxg/UeLO7ienhdI/AAAAAAAAFH0/lcZSgtqtOGw/s1600/manatees.jpg" title="manatees" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">manatees</td></tr>
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The sirenians, also called sea cows, evolved from the hoofed land mammals, like the cetaceans. The Sirenia include the <b>manatees</b>, which are large plant-eating marine mammals, and the dugongs (commonly known as sea cows). They are the only plant-eating marine mammals, eating sea grasses and algae (tiny rootless plants that grow in sunlit waters) in warm waters. They grow to be quite large, up to 15 feet (4.5 meters) and weigh 1,500 pounds (680 kilograms).<br />
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<b>Endangered Marine Mammals</b><br />
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According to the Endangered Species Act, an animal that could become extinct in all or part of its range is endangered. An animal’s range is the entire area where it lives. Of the 115 species of marine mammals, 22 were considered endangered as of 2004, including the blue whale, the gray whale, the finback whale, the Hawaiian monk seal, the stellar sea lion, the marine sea otter, and all four species of dugongs and manatees. Much of the threat is due to human activity. People hunt these animals for their pelts, blubber, and meat, and destroy their habitat from overfishing and mining.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-11580752126821132902013-07-14T20:07:00.000+07:002017-03-01T19:41:01.376+07:00Plankton<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/06/psychotherapy.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="the bioluminescent noctiluca scintillans — an algae known otherwise as sea sparkle — of australia’s jervis bay." border="0" src="https://2.bp.blogspot.com/-t5k7ZHfVDX8/WLbAAVSCfAI/AAAAAAAAd4Y/AVzol3hmg3gxC6I-G0c9y_IQMeNgr8OCACLcB/s1600/plankton.jpg" title="the bioluminescent noctiluca scintillans — an algae known otherwise as sea sparkle — of australia’s jervis bay." width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">plankton in australia’s jervis bay.</td></tr>
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Plankton is a general term that includes plants, animals, and bacteria that drift through lakes and the oceans. Plankton are the foundation for all life in the <a href="http://be-eco-friendly.blogspot.com/2010/10/ocean-dumping.html" target="_blank">ocean</a> and produce much of the oxygen that sustains life on Earth. Plankton represents a diverse and large group of organisms. <br />
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Often, the only factor that the nearly ten thousand different species of plankton have in common is their poor swimming ability. Rather than control where they are moving, like fish, whales, and turtles, plankton simply float wherever the water currents take them. In fact, the word plankton is derived from the Greek word planktos, meaning “to wander.”<br />
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<b>Studying and classifying plankton</b><br />
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Biologists identify and count plankton found in water samples. Several different methods are used to collect plankton from water samples, the most common of which includes the use of plankton nets. Most plankton nets are made of nylon or synthetic material that is produced so that the size of the holes between the fibers is uniform. The most common shape for a plankton net is cone-shaped, and the large end of the cone is attached to a metal net ring. <br />
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The diameter of the net ring is usually 39 inches (1 meter). The small end of the cone is fitted with a plastic bottle, called a net bucket. The net is pulled slowly behind a boat for a specific distance and plankton larger than the holes in the net are trapped in the net bucket. The net is then reeled into the boat and the plankton trapped in the net bucket are removed for study.<br />
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Once the plankton have been removed from the net bucket, scientists identify and count the different species of animals and plants. Once the number of a certain type of plankton found in the net bucket has been counted, biologists calculate the concentration of that organism. The volume of water sampled can be calculated by multiplying the distance the net was towed by the area spanned, by the net ring.<br />
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The concentration of different types of plankton gives biologists information about the water quality and ecology (study of the relationships between organisms and their environment). Biologists also use some of the larger and sturdier plankton removed from the net bucket for experiments involving <a href="http://trytostayhealthy.blogspot.com/2011/02/nutrition.html" target="_blank">nutrition</a>, reproduction, and different processes in the human body.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://lifeofplant.blogspot.com/2011/04/ecology-concept.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Blue buttons plankton" border="0" src="https://3.bp.blogspot.com/-btQ4ZNRjMEA/WLbA7GuB3YI/AAAAAAAAd4g/QPAPlbeuUDAHmWQ4liNRIFTfx5GJhZpKACLcB/s1600/Blue-plankton.jpg" title="Blue buttons plankton" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Blue buttons plankton</td></tr>
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Many plankton are extremely small and pass through even the smallest holes in plankton nets. In order to study these plankton, biologists filter a specified amount of sample water through membranes (tissue) that have very small holes. The water will pass through the <a href="http://lifeofplant.blogspot.com/2011/02/plasma-membranes.html" target="_blank">membranes</a>, but any plankton larger than the holes in the membranes will be concentrated on top. <br />
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Researchers can then attach the membranes to slides and view them under a microscope. Special dyes are often used to stain the plankton in order to see them more clearly. In other cases, the membranes with the plankton on them are ground up and are analyzed chemically, which helps researchers determine the types of plankton in the water.<br />
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Because there are so many different types of plankton, counting and identifying them is time-consuming and often difficult. Instead, biologists often classify plankton into broad groups that simplify the process, but still provide important information about the ecology of the water sample. Three criteria often used for plankton classification are size, cell structure, and life history.<br />
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Size of plankton There are six major size categories of plankton. They range in size from plankton far too tiny to be seen with the naked eye to organisms that are many feet (meters) long. <br />
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<li><b>Net plankton</b>: These plankton include species that are large enough to be caught in <a href="http://amzn.to/2kmeb5x" rel="nofollow" target="_blank">plankton nets</a>.</li>
<li><b>Macroplankton</b>: Plankton larger than 0.79 inches (more than 20 millimeters) are called macroplankton. Macro is the prefix meaning “large.” Macroplankton include the larval (immature worm-like stage) forms of many fish, some marine worms, many different types of crustaceans (water animals with an outside skeleton, including shrimp, crabs, lobsters) and jellyfish that can have tentacles stretching 25 feet (8 meters). Some plants are also classified as macroplankton, such as the giant <a href="http://trytostayhealthy.blogspot.com/2011/01/sargassum-seaweed.html" target="_blank">seaweed Sargassum</a>.</li>
<li><b>Mesoplankton</b>: Plankton between the sizes of 0.79 to 0.0079 inches (20 to 0.2 millimeters) are called mesoplankton. The prefix meso means “medium.” Examples of mesoplankton are shrimp-like creatures called <b>euphausids</b> and many types of larval fish.</li>
<li><b>Microplankton</b>: These plankton range between 0.0079 to 0.000079 of an inch (between 0.2 and 0.02 millimeters. The prefix micro means “small.”</li>
<li><b>Nannoplankton</b>: Plankton between 79 ten-thousandths to 79 millionths of an inch (between 0.02 to 0.002 millimeter) are called nannoplankton. These plankton are so small they must be concentrated on filters in order to be identified. The prefix nanno means “very small.” These plankton include many different types of protozoans (a type of onecelled animal), single-celled plants, and the larvae of crabs, sea urchins, and mollusks.</li>
<li><b>Picoplankton</b>: The smallest group of plankton is the picoplankton, which are less than 79 millionths of an inch (2 thousandths of a millimeter or 0.0002 millimeters) wide. Picoplankton are the smallest and most numerous plankton in the ocean. The prefix pico means “extremely small.” Picoplankton include bacteria that ingest organisms for food organisms, as well as a type of bacteria that can gather energy from the Sun as do plants. Picoplankton also include many different species of single-celled protozoans and single-celled plants.</li>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2011/11/surface-and-groundwater-use.html" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;" target="_blank"><img alt="euphausids" border="0" src="https://1.bp.blogspot.com/-r8NtZLm7ozs/UeKfAsJdSoI/AAAAAAAAFGk/Eg5Tp2iag-w/s1600/euphausids.jpg" title="euphausids" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">euphausids</td></tr>
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Cell structure of plankton. Plankton are classified into three major groups according to cell type: phytoplankton, zooplankton, and bacterioplankton.<br />
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<b>Phytoplankton</b>: Phytoplankton are plants and oxygen-like bacteria. The prefix phyto means “plant.” Most phytoplankton are single-celled organisms, although there are some phytoplankton that form colonies (groups) and others that are multicellular, such as seaweed. In the open oceans, about three-fourths of phytoplankton are nannoplankton. In coastal waters and lakes, phytoplankton tend to be larger, in the microplankton size range. <br />
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Diatoms are the most numerous group of phytoplankton. Diatoms are single-celled plants that can be shaped like rods, spools of thread, or pillboxes (round boxes with a top and bottom of equal height). They secrete two shells made of silicon, the same substance that makes up glass. <br />
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The plant cell lives inside the silicon shells and produces threads that protrude through perforations in the shells. In some <a href="http://watersome.blogspot.com/2011/11/species-introduction.html" target="_blank">species</a>, the threads join with threads on other diatoms and form long chains. Diatoms are usually found in the surface waters and when conditions are right, they can reach high concentrations that can make the water appear green.<br />
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After diatoms, dinoflagellates are the next most common group of phytoplankton. Dinoflagellates come in many different shapes, but commonly look like a chocolate candy kiss placed bottom to bottom with another candy kiss that has two peaks instead of one. <br />
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Most have two flagella (whiplike appendages) that they use like propellers to spin through the water. Some are covered with protective plates composed of cellulose, the material that makes up the woody part of trees. A few species of dinoflagellates contain chemicals that poison fish and, occasionally, people. Other dinoflagellates contain pigments that make the ocean appear red.<br />
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</b> <b>Zooplankton</b>: Zooplankton are animal plankton that wander in the water currents. Because they are poor swimmers, most zooplankton have special feeding structures that allow them to capture food that they bump into as they drift. These structures come in all forms, from sticky hairs to nets made out of mucous, to brush-like appendages that sweep food particles toward the mouth. Most zooplankton diet on phytoplankton.<br />
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The most common zooplankton in the ocean are the crustaceans, which include the crabs, shrimp, and lobsters, and account for about 70% of all zooplankton. In particular, a small shrimp-like animal called the copepod is the most numerous type of animal in the plankton family. <br />
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In fact, if all the copepods in the world were divided equally among all the people in the world, each person would receive one billion copepods. Another common zooplankton is the shrimp-like crustacean called the euphausid. Euphausids, also called krill, are slightly bigger than copepods, around 2 inches (5 centimeters) long. <br />
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They are so numerous in the waters around Antarctica that the diet of many whales consists entirely of krill. In fresh water, the tiny crustacean Daphnia is the most numerous zooplankton. Daphnia are particularly interesting zooplankton because they can reproduce without mating in the spring and summer using a process called parthenogenesis, where female Daphnia produce exact copies of female offspring.<br />
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Other important animal groups found among zooplankton are the jellyfish, the worms, the mollusks (squid and snails), and the echinoderms (sea cucumbers and sea urchins). Some zooplankton are single-celled organisms called protozoans. For example, the foraminifera are a type of amoeba (a one-celled animal) that has a shell with holes through it. Foraminifera produce sticky spines that extend through the holes, where animals that bump into them are captured and eaten.<br />
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<b>Bacterioplankton</b>: The smallest type of plankton, bacterioplankton are microscopic single-celled organisms. Along with other forms, they play an important role in the ecology (living organisms and their environment) of <a href="http://lifeofplant.blogspot.com/2011/12/aquatic-plants.html" target="_blank">aquatic</a> systems. Bacteria are single-celled microscopic organisms. These organisms are numerous. Bacteria digest dead zooplankton and phytoplankton, producing the nutrients and other materials needed for new life to grow.<br />
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<b>Life history of plankton</b><br />
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Plankton are also classified according to their life history. Most species of bacterioplankton, phytoplankton, and zooplankton spend their entire life floating and drifting with the currents. These plankton are called holoplankton (holos is the Greek root meaning “entire”).<br />
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Other plankton live only the early part of their life as plankton; the adult part of their life is spent in a different part of the ocean or lake. These plants and animals are called meroplankton (meros is the Greek root meaning “mixed”). <br />
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Some examples of meroplankton are sea urchins, sea slugs, lobsters, worms, and some coral reef fish. Some aquatic plants are also meroplankton. Many meroplankton scatter eggs into the plankton, where they are fertilized. The fertilized eggs develop into larvae, which float in the plankton. Just as a caterpillar looks nothing like a <a href="http://be-eco-friendly.blogspot.com/2011/01/bay-checkerspot-butterfly.html" target="_blank">butterfly</a>, in general these larvae look nothing like the adults they will eventually become. <br />
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When the larvae are in the plankton, they eat other plankton or survive off of the yolk that was with them in the egg. Depending on the species, the larvae remain in the plankton for varying periods of time from several days to several months. Afterwards, the larvae settle onto the seafloor or swim away from the plankton and change into their adult form.<br />
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<b>Importance of plankton</b><br />
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Plankton are vital to the global climate. Phytoplankton perform photosynthesis, which is a process that uses the energy from sunlight to produce food. In the process of <a href="http://lifeofplant.blogspot.com/2011/03/photosynthesis.html" target="_blank">photosynthesis</a>, phytoplankton take in carbon dioxide and produce oxygen. About half of the oxygen on the planet comes from phytoplankton photosynthesis. <br />
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As humans burn oil and gas to keep their cars moving and their houses warm, carbon dioxide is produced. This carbon dioxide holds heat and is one of the leading causes of global warming. It is estimated that phytoplankton remove three billion tons of carbon dioxide from the atmosphere each year, as much as all the trees on land.<br />
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Plankton are also key to the ecology of the ocean. Phytoplankton are the base of the marine food chain. In other words, they are the food for zooplankton, corals, and mollusks. Even some sharks, such as basking sharks and nurse sharks, rely on phytoplankton for their diet. In turn, fish and larger predators eat the zooplankton. In fact, the giant <a href="http://be-eco-friendly.blogspot.com/2011/03/blue-whale.html" target="_blank">blue whale</a> relies entirely on shrimp-like zooplankton called euphausids for its diet. Humans also eat fish that prey on plankton.<br />
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After plankton die, they sink to the bottom of the ocean. Over millions of years, the dead plankton are buried by sediments, and then eventually converted into fossil fuels such as oil and gas.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-55443259863102740182013-07-14T19:00:00.000+07:002017-03-04T18:26:58.112+07:00Tides<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.co.id/2016/07/peppermint.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Tides" border="0" src="https://3.bp.blogspot.com/-JA_cF5Nqfd4/WLqjE-yGTJI/AAAAAAAAeDA/MLQ7iuFUwpoJngW3Cazle5mcJsHCBhZawCLcB/s1600/tides.jpg" title="Tides" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Tides</td></tr>
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Tides are the alternating rise and fall of bodies of water, relative to land. Each 24-hour period, there are two high tides and two low tides. The arrival times and heights of the tides change every day and follow a pattern over days, months, and seasons. <br />
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The shape of a coastline, water depth, shape of the seafloor (bathymetry), weather, and other local factors affect the heights and arrival times of tides at specific locations. The daily tides bring ocean nutrients that nourish brackish-water (slightly salty) plants and wildlife that live in tidal wetlands.<br />
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<b>Explaining the tides</b><br />
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Humans in maritime (sea-going and coastal) societies have always recognized and measured the daily, monthly, and yearly pattern of water level rise and fall along coastlines. Navigation, construction, and fishing in coastal areas require precise knowledge of the local tides, and tide prediction is an ancient science. The ancient Hawaiian “moon calendar” charts the tides and relates them to <a href="http://watersome.blogspot.com/2011/11/fishing-commercial-regulation-fresh-and.html" target="_blank">fishing</a> and agricultural harvests. <br />
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John, Abbot of Wallingford, who died in 1213 supposedly authored the oldest European tide chart. One entry predicts the hours of high water at London Bridge (“flod at london brigge”) on the <a href="http://amzn.to/2m73eUy" rel="nofollow" target="_blank">Thames River</a>. The scientific explanations for how the tides work and why they occur are, however, relatively new discoveries. <br />
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Ancient Chinese and European philosophers theorized that Earth inhaled and exhaled water. Most ancient scientists, including Greek philosopher <a href="http://earlyworldhistory.blogspot.com/2012/04/aristotle-greek-philosopher.html" target="_blank">Aristotle</a> (384–322 B.C.E.), were silent on the subject of tides. (Ancient Egyptians, Greeks, and Romans lived on the Mediterranean Sea, which has relatively insignificant tides.)<br />
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Isaac Newton’s theory of gravity is the basis for understanding tides. <a href="http://epicworldhistory.blogspot.com/2012/05/isaac-newton.html" target="_blank">Isaac Newton</a> (1642–1727), a seventeenth century English mathematician and physicist, theorized that all objects exert an attractive force, called gravity, on other objects. The strength of the gravitational pull between objects depends on their relative sizes and the distance between them. <br />
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Earth, a very large object, pulls smaller objects, like people or apples, strongly toward its center. (Newton’s theory of gravity was supposedly inspired by his observation of an apple falling from a tree.) Earth’s gravitational pull keeps the Moon in orbit around the planet. Newton’s ideas were later applied to an explanation of tides by French mathematician <a href="http://amzn.to/2mQaB15" rel="nofollow" target="_blank">Pierre Simon Laplace</a> (1749–1827), and Irish physicist William Thomson (1824–1907), who is also known as Lord Kelvin.<br />
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<b>How tides work</b><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://lifeofplant.blogspot.com/2011/04/european-flora.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="How tides work" border="0" src="https://4.bp.blogspot.com/-OWezxaufM74/UeKQfpUdhuI/AAAAAAAAFFw/Sb2E-A8X_yo/s1600/tides-how.jpg" title="How tides work" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">How tides work</td></tr>
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The gravitational pull of the <a href="http://agemythologystories.blogspot.com/2011/05/moon-epic.html" target="_blank">Moon</a> and Sun on Earth’s oceans, inland seas, and large lakes causes tides. The Moon’s pull on the surface of the oceans as Earth spins on its axis causes two high tides and two low tides during each 24-hour day. To visualize the tides, imagine Earth as a ball completely covered with water. <br />
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Earth’s gravity holds the water on the planet’s surface. The Moon’s gravity pulls a bulge of water toward it. Another force due to the spinning of the Earth and called the centrifugal force also bulges water at the equator in an outward direction, much like a fast-spinning amusement ride pushes your body toward one side of your seat. <br />
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Centrifugal force causes a second bulge to form on the direct opposite side of Earth to balance the bulge facing the Moon. As Earth rotates on its axis over 24 hours, the bulges remain stationary with respect to the Moon. Every location on Earth experiences the passing of both bulges in the form of two high tides each day. The low water moments between the bulges cause two daily low tides. <br />
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The relative positions of the Earth, Moon, and Sun constantly shift. The Moon’s monthly circuit around Earth causes the tides to occur slightly later each day. If the Moon were stationary over the spinning Earth, the high tides would be exactly 12 hours apart, and tides would occur exactly every six hours. As it is, the first high tide of a 24-hour day happens about 50 minutes later than the previous day.<br />
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The gravitational pull of the Sun also affects the height of the tides. Solar (sun) tides are much weaker than lunar (moon) tides because the Sun, although much larger than the Moon, is much farther away from Earth. The relative positions of the Earth, Moon, and Sun constantly change during Earth’s year-long trip around the Sun. Very high and very low tides, called spring tides, occur when the Sun and Moon are aligned and pulling at the tidal bulges from the same or exact opposite sides of Earth. <br />
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Spring tides happen twice a month (about every 15 days) during the new and full moons. The opposite conditions, when high tide is not very high and low tide is not very low, are called neap tides. These happen when the Moon and Sun are at right angles to each other so their gravitational forces cancel one another.<br />
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</b> <b>Tides vary around the world</b><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/05/sesame-oil.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Tides vary around the world" border="0" src="https://2.bp.blogspot.com/-CRRptJSSfjI/UeKRtP8cW9I/AAAAAAAAFF8/66BvdVbiYyU/s1600/blue-tides.jpg" title="Tides vary around the world" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Tides vary around the world</td></tr>
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Earth is obviously not a perfect, water-covered sphere. The continents, seafloor, ocean currents and (mass of air surrounding Earth) winds all affect the tidal bulges as they move around Earth each day. Some places, like the <a href="https://www.amazon.com/gp/product/B00186V4M8/ref=as_li_tl?ie=UTF8&tag=theconthist-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B00186V4M8&linkId=154950aec36055cbe5b3e4fac731ecb4" rel="nofollow" target="_blank">Bay of Fundy</a> in Nova Scotia, Canada, and the English Channel between Great Britain and France, experience very large tides. <br />
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Other places, like the Mediterranean Sea, have barely noticeable tides. Sometimes the shape of an inlet (a narrow body of water between two islands or leading inland), bay, or harbor delays the tides; in the Gulf of Mexico there is only one high and one low tide each day. <br />
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A large storm like a hurricane can add to the tidal bulge as it approaches the shore. Along many coastlines, strong tides carry salt water and ocean sediment (particles of sand, gravel, and silt) far inland. Many rivers, bays, and estuaries (coastal wetlands) experience tides many miles from the ocean. Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-76446689366817464612013-07-14T18:01:00.000+07:002017-02-22T19:19:32.089+07:00Waves<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2015/11/trepanation.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Waves" border="0" src="https://4.bp.blogspot.com/-b4xWalWZIGk/WK1-HSaI19I/AAAAAAAAdig/lDu58nKS2OA_JmY8Qby8NKIBeM03sBvdgCLcB/s1600/wave.jpg" title="Waves" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Waves</td></tr>
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Wind creates waves. As an air current (moving stream of air) moves over an undisturbed water surface, friction between air and water creates a series of waves that move across the surface. The size of the waves depends on the wind speed, the duration of the wind, and the distance over which the wind blows. (The distance of open water surface that the wind blows over is called the fetch.) A week-long tropical storm in the <a href="https://www.amazon.com/gp/product/1484607775/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=1484607775&linkId=821daf6a816da576257a7b6be5c5595b" rel="nofollow" target="_blank">Pacific Ocean</a> might produce waves as tall as three-story houses; a ten minute gust blowing across a small lake might make waves that are only a few inches tall.<br />
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Waves move away from their point or area of origin in widening circles, like ripples moving away from a pebble dropped into a pool. In an <a href="https://www.amazon.com/gp/product/B01E3IIOAM/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B01E3IIOAM&linkId=20b33490738c67cbd5daf386a51b6eca" rel="nofollow" target="_blank">ocean basin</a> (the deep ocean floor), waves from many different wind events are moving across the sea surface at any given moment. When sets of waves meet they interact to form new patterns. By the time they reach the coastline, waves have been affected by many wind events.<br />
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Ocean waves may appear that the water is moving forward but in actuality the water is moving in a circle as the water molecules lift and fall. (A molecule is the smallest unit of a substance that has the properties of that substance.) Imagine floating in the ocean in a raft. <br />
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When a wave approaches, you rise and fall as it passes, but you don’t move toward the beach. The same thing happens to the water molecules below you. As a wave arrives, the water particles rise and fall in small circles as the wave passes, but they are not carried forward. The highest point the wave reaches is called the crest. <br />
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The lowest point of the wave is called the trough. The wavelength is the distance from one crest to the next. The water molecules closest to the surface move in the largest circles, and deeper water moves less. Molecules below a depth known as wave base are undisturbed by a passing wave. Wave base is equal to half the horizontal distance between wave crests, or one-half a wavelength.<br />
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<b>Breaking waves</b><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2015/04/wormwood.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="big wave surfing" border="0" src="https://4.bp.blogspot.com/-1RIR6yip1Ug/WK1-7YC3HoI/AAAAAAAAdio/CKvpzwSC4DciMfQWsq7pNY9sE2Qt-8zhQCLcB/s1600/big-wave.jpg" title="big wave surfing" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Breaking waves</td></tr>
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Waves change form when they approach a coastline. When the seafloor is shallower than the wave base, it interferes with the circular motion of the water at the bottom of the wave. Waves that were broad, gentle swells in the open ocean grow taller and their crests get closer together. Eventually, the wave grows too tall to support itself and it breaks; the wave crest collapses over the front of the waves. <br />
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Spilling breakers that gradually become more steep and then crumble typically form along shallowly sloping shores. Plunging breakers that grow tall and curl sharply generally pound steep coastlines. Big waves start to break farther from shore than smaller waves because they have deeper wave bases.<br />
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Water from breaking waves sloshes forward up the beach. It returns in an outgoing current along the seafloor called undertow. The forward and back motion of water in the surf zone (area of rough water next to the land, where ocean waves hit the shore) between the breaking waves and the beach is called swash. <br />
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Like water in a washing machine, water in a surf zone endlessly cycles between the breakers and the beach. Beaches are subjected to relentless swashing that breaks down all but the most resistant sediments (sand, gravel, or silt). The mineral quartz is particularly strong, and beach sand is often composed of identical quartz grains that waves have rounded into perfect spheres and sorted by size.<br />
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<b>Wave refraction</b><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/05/shin-splints.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Wave refraction - San juanico baja california sur, Mexico" border="0" src="https://4.bp.blogspot.com/-LjAED9Xbx2c/WK1_uDcJrYI/AAAAAAAAdiw/piv5SejwQeIOk9iBwnA1C8gdpc_hOFWRgCLcB/s1600/refrac.jpg" title="Wave refraction - San juanico baja california sur, Mexico" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Wave refraction - San juanico baja california sur, Mexico</td></tr>
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Waves bend when they reach coastlines. It is extremely rare for wind to blow exactly toward a perfectly straight coastline, and waves almost always approach shorelines at an angle. Wave bending or refraction occurs because the end of a wave that reaches shallow water first slows down and breaks before the deeper end. Water moving in the surf zone flows sideways along the beach from the direction of the approaching wave, and gravity pulls the returning water directly downhill. <br />
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Water and sediment thus move in a zigzag pattern that carries them along the beach. Wave refraction produces longshore currents, which are currents that flow parallel to coastlines in shallow water. If you have ever dropped your towel on the beach and gone for a swim only to discover that you have been carried away from your towel, you have experienced a long-shore current.<br />
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Wave refraction also brings the eroding power of waves onto headlands, the jagged, rocky, narrow strips of land that extend into the ocean. Longshore currents carry the eroded sediment away from headlands and deposit it in bays. Waves thus, straighten irregular coastlines by wearing down the headlands and filling the bays. A typical arc-shaped bay with headlands at each end has two longshore currents that flow from the headlands toward each other. <br />
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The shallow, strong, outgoing current that forms at the tip of the bay where they meet is called a rip current. Rip currents also form where large waves pile water between a sand bar (a ridge of sand built up by currents) and a beach. Rip currents, can be dangerous to swimmers because they can form or become strong suddenly.<br />
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Waves and longshore currents can also mold sand into strings of barrier islands (a long, narrow island parallel to the mainland) formed from sediment deposits. These islands are often called depositional coastlines. In the Gulf of <a href="http://epicworldhistory.blogspot.com/2012/05/basin-of-mexico.html" target="_blank">Mexico</a>, waves have washed sand from the Mississippi River <a href="http://watersome.blogspot.com/2013/07/deltas.html" target="_blank">Delta</a>. <br />
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Longshore currents have deposited the sand in a long streamer of barrier islands along the Louisiana and Texas coastlines. Tidal inlets (inlets maintained by the tidal flow) separate barrier islands from each other and shallow bays called lagoons separate them from the mainland. The barrier island of the United States eastern seaboard, included the Outer Banks of the Carolinas, formed in a similar fashion. <br />
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Wave patterns and coastline conditions are constantly changing, and coastline features are continuously remolded. The waves from a large hurricane, for example, can completely destroy a barrier island, beach houses and all, and reshape a new one in a matter of days.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-49935506404114030782013-07-14T16:46:00.004+07:002017-02-22T20:05:44.111+07:00Deltas<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2012/09/ice-sea-level-and-global-climate.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Deltas" border="0" src="https://4.bp.blogspot.com/-wbKgXbeRaFY/UeHaJiCFw5I/AAAAAAAAFDY/tTalrx6f-TE/s1600/river-delta.jpg" title="Deltas" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Deltas</td></tr>
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Deltas are deposits of sediments (particles of sand, gravel, and silt) at the mouths of rivers that flow into the ocean. The mouth of a river is the end where the body of water flows into the sea. Deltas are shaped by interactions of the river’s fresh water with the ocean water, tides, and waves. Throughout history, deltas have been important places for human settlement. They are also vital habitats for many animals and plants. <br />
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In the fifth century B.C.E, Greek naturalist <a href="http://earlyworldhistory.blogspot.com/2012/03/herodotus-thucydides-and-xenophon.html" target="_blank">Herodotus</a> coined the name delta to describe the triangular shape of the sediments deposited at the end of the Nile River. The capital Greek letter delta (∆) resembles a triangle. Most deltas are triangular in shape because rivers deposit larger amounts of sediment where they meet the sea, then fan out into the mouth of the sea to deposit the remaining sediment.<br />
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<b>Formation of Deltas</b><br />
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As rivers flow through their beds (a channel occupied by a river), the water breaks up rocks and pebbles, which the river then carries with it as it flows. These pieces of rock, sediment, include sand, pebbles, and silt. When the fast-flowing waters of the river reach the ocean, they push against the ocean water. <br />
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This decreases the speed of the river water, which spreads out along the coastline. As the speed of the river water slows, the sediments that it carries settle to the bottom of the <a href="http://be-eco-friendly.blogspot.com/2010/10/ocean-dumping.html" target="_blank">ocean</a>. Over time, the sediments accumulate and form a delta.<br />
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In most deltas, the river water is less dense (packed together) than the sea water because it contains less salt. As it flows out into the ocean, it floats on top of the ocean water. This is called hypopycnal flow. (The prefix hypo means “under” or “less” and the root word pycn means “density.”) <br />
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In places where hypopycnal flow occurs, the salt water that lies under the fresh water is called a salt wedge. The bigger sediments, like gravel and pebbles, are deposited at the tip of the salt wedge (nearest to shore) and the smaller sediments, like sand, are deposited farther out along the salt wedge. The smallest silt grains (fine sediment particles) are transported far offshore with the river water.<br />
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<b>The Structure of a Delta</b><br />
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Paths of flowing water called channels run through the sediments of deltas. These channels are called distributaries and they may be large and relatively permanent or small, transient features. The sides of the channels are made up of piles of sediments called levées. The areas between the distributaries are called interdistributary areas.<br />
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<b>Types of Deltas</b><br />
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The structure of the distributaries and interdistributary areas depends on where the river empties into the ocean and the forces that affect the river water as it flows into the ocean. There are three major types of deltas: river-dominated, tide-dominated, and wave-dominated. Many deltas are formed by a combination of these forces.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/05/sound-therapy.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt=" The Mississippi River Delta in Louisiana" border="0" src="https://4.bp.blogspot.com/-ucAFoRnJe7E/WK2C9_SG25I/AAAAAAAAdi8/w-YrafIR81g9PpIm5qq0YAPwRBpKu-dqwCLcB/s1600/missisipi-delta.jpg" title=" The Mississippi River Delta in Louisiana" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The Mississippi River Delta in Louisiana</td></tr>
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River-dominated deltas extend outward from the coast as the river water jets out into the ocean. The sediments deposited by the <a href="http://be-eco-friendly.blogspot.com/2011/03/chinese-river-dolphin.html" target="_blank">river</a> tend to form levées that hold channels of water. The aerial view of a river-dominated delta looks like the foot of a bird with several branching channels. River-dominated deltas often have sand bars (long deposits of sand) that are perpendicular to the river. The Mississippi River Delta in Louisiana is an example of a river-dominated delta.<br />
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Tide-dominated deltas are deltas where the sediments deposited by a river are redistributed by tides. These deltas have channels cut by the river water as well as channels cut by tidal currents. The result is a shoreline that looks like the fringe on the end of a carpet. <br />
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Tide-dominated deltas may also have coastal features like sand bars and shoals (a sandbank seen at low tide) oriented parallel to the tidal flow. The Ganges-Brahmaputra Delta in the Bay of Bengal is an example of a tide-dominated delta.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2012/09/bioaccumulation-of-heavy-metals.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Ganges-Brahmaputra Delta" border="0" src="https://3.bp.blogspot.com/-bLbIPfglvDQ/UeHhenSsuMI/AAAAAAAAFEk/ZeP8MKlWNcQ/s1600/delta-ganges.jpg" title="Ganges-Brahmaputra Delta" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ganges-Brahmaputra Delta</td></tr>
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Wave-dominated deltas occur in places where the sediments deposited by the river water are redistributed by waves. Because waves tend to move sediments along the shoreline, the shape of wave-dominated deltas is usually a smooth coastline. <br />
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If the waves that affect the delta break parallel to the shoreline, the sediments of the delta will tend to be symmetrical on either side of the river. If the waves break at an angle to the shore, the sediments of the delta will tend to accumulate on one side of the delta. The Nile River Delta in Egypt is an example of a delta that is wave-dominated.<br />
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<b>Humans and Deltas</b><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2012/09/desertification.html" imageanchor="1" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Humans and Deltas" border="0" src="https://3.bp.blogspot.com/-lTTVodxTXdw/UeHcrUPE2WI/AAAAAAAAFD0/Xd8QNBpoFo8/s1600/delta-1.jpg" title="Humans and Deltas" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Humans and Deltas</td></tr>
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Deltas play an important role in human life both historically and in present times. The land on deltas is typically very good for agriculture. On the parts of the delta close to the river, the soil is fertilized each year by nutrient-containing floodwaters when the river <a href="http://watersome.blogspot.com/2012/09/floods-and-flood-control.html" target="_blank">floods</a>. <br />
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In addition, by building aqueducts (canals or pipelines used to transport water) from the wetter lands near the river to the dryer lands farther from the water source, it is easy to expand the amount of land available for farming. This practice is called land reclamation. In particular, the fertile Nile delta has supported much of the agriculture in Egypt for thousands of years.<br />
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Trade is another reason why humans have lived on deltas. Because of the many distributaries and the access to a major river and the ocean, deltas are regions where goods can be easily exported both inland and overseas. Many of the world’s largest ports are in deltas. Also, communication is relatively easy in deltas. Because the land is usually flat, it is easy to build roads. The many <a href="http://watersome.blogspot.com/2011/11/shipping-on-freshwater-waterways.html" target="_blank">waterways</a> make boat travel easy as well.<br />
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<b>Life on Deltas</b><br />
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<a href="http://watersome.blogspot.com/2012/09/habitat-loss-and-species-extinction.html" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;" target="_blank"><img border="0" src="https://2.bp.blogspot.com/-l_xfq-7iFig/UeHbszRainI/AAAAAAAAFDo/FHof3oes8Q8/s1600/delta-life.jpg" /></a></div>
The interdistributary areas of deltas can support a variety of different habitats, depending on whether they are closer to the freshwater of the river or the salt water of the ocean. If the interdistributary areas are close to the river and affected by annual floods, they are called floodplains. <br />
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Other interdistributary areas near the river water may be <a href="http://be-eco-friendly.blogspot.com/2011/01/california-freshwater-shrimp.html" target="_blank">freshwater</a> marshes, freshwater swamps, or lakes. The interdistributary areas that are closer to the ocean are likely influenced by the tides. They may be tidal flats (flat, barren, muddy areas periodically covered by tidal waters), mangrove (a tree that grows in saltwater) swamps, salt marshes, or <a href="http://watersome.blogspot.com/2011/11/marine-archaeology.html" target="_blank">marine</a> embayments (an indentation in the shoreline of the sea that forms a bay).<br />
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Because deltas have such a broad range of environments, they host a diversity of species. Many different species of plants flourish on deltas, from saltwater trees called mangroves, to sea grasses, swamp sedges, and shrubs. Deltas also serve as nursery grounds for many species of fish and invertebrates (animals without a spine) and many land animals such as snakes and birds. The marine (sea) areas are important habitats for burrowing worms and mollusks, crustaceans (sea animals with hard outer shells) that hunt for food along the seafloor, as well as a variety of different species of fish.<br />
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<a href="http://watersome.blogspot.com/2011/11/aquariums.html" imageanchor="1" target="_blank"><img border="0" src="https://4.bp.blogspot.com/-6-Gt6WP9dzw/UeHeNoZyp-I/AAAAAAAAFEE/JAVfzClW7vs/s1600/delta-wild.jpg" /></a></div>
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Deltas also serve important environmental roles. They remove harmful chemicals that are deposited in them by river pollution. These chemicals are absorbed by sediments and trapped as new sediments settle on top. Over time, bacteria break down many of these harmful substances and release chemicals that are not dangerous to the health of humans or other animals. Deltas are also known as nutrient recharge zones. When animals and plants die, they are buried in sediments and bacteria digest them. This converts the chemicals in their bodies into the raw materials needed for plants to grow.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-74128545186727150442012-09-30T11:00:00.003+07:002017-02-22T22:47:59.650+07:00Freshwater Life<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/05/sleep-apnea.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Freshwater Life" border="0" src="https://4.bp.blogspot.com/-nUjRSH62haY/WK2f_E_f1xI/AAAAAAAAdjM/39Sb4o7XybYXAATN04gQ4RLPIRL_N3VHACLcB/s1600/freshwater-life.jpg" title="Freshwater Life" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Freshwater Life</td></tr>
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The animals and plants that live in freshwater are called aquatic life. The water that they live in is fresh, which means that it is less salty than the <a href="http://be-eco-friendly.blogspot.com/2010/10/ocean-dumping.html" target="_blank">ocean</a>.The terrestrial (land) environment that surrounds the freshwater environment has a large impact on the animals and plants that live there. Some factors that influence the freshwater environment include climate, soil composition, and the terrestrial animals and plants in the area.<br />
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Just as on land, aquatic plants require carbon dioxide, nutrients (substances such as phosphate and <a href="http://lifeofplant.blogspot.com/2011/03/nitrogen-cycle.html" target="_blank">nitrogen</a> needed for growth) and light for photosynthesis, the process where plants make their food from sunlight, water, and carbon dioxide. Aquatic animals need to breathe in oxygen and consume food. <br />
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The physical conditions surrounding the body of water or wetland (lands that are covered in water often enough so that it controls the development of the soil) control the availability of these resources. <br />
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<td align="center"><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/gp/product/0226668169/ref=as_li_ss_il?ie=UTF8&linkCode=li3&tag=waterabout-20&linkId=0baf5cc8104096dbd6d8b6d8e4cba341" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=0226668169&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=0226668169" style="border: none !important; margin: 0px !important;" width="1" /></span><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/gp/product/0754817644/ref=as_li_ss_il?ie=UTF8&linkCode=li3&tag=waterabout-20&linkId=6c211acb7da3eadae9d3f09c5d444fc2" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=0754817644&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=0754817644" style="border: none !important; margin: 0px !important;" width="1" /></span></td>
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For example, the concentrations of nutrients, oxygen, and carbon dioxide in the water depend on how much air gets into the water and on the chemical composition of the land nearby. The sediments (particles of sand, gravel, and silt) in the water influence how much light reaches the bottom of the lake or river. <br />
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The temperature of the water affects how quickly animals and plants grow. The <a href="http://amazingrainbow.blogspot.com/2009/12/characteristics-of-good-leader.html" target="_blank">characteristics</a> of the bottom of the body of water (sand, mud, rocks) and the speed of the currents (horizontal movement of water) control what kinds of plants and animals can live and reproduce in an area.<br />
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In general, freshwater environments are divided into two major categories: lentic waters and lotic waters. Lentic waters are those that are moving, as in rivers and streams. Lotic waters are those that are stationary, as in <a href="http://watersome.blogspot.com/2012/09/lakes.html" target="_blank">lakes</a> and ponds. <br />
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Sometimes, however, rivers and streams flow into lakes and <a href="http://watersome.blogspot.com/2012/09/ponds.html" target="_blank">ponds</a> and the two different habitats merge together. Some wetlands may also contain many characteristics of freshwater environments.<br />
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<b>Life in rivers and streams</b><br />
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Rivers and streams are characterized by several physical features. They are generally comprised of freshwater that flows in one direction. The flow of water is most often from an area of high altitude (like a <a href="http://be-eco-friendly.blogspot.com/2011/03/mountain-pygmy-possum.html" target="_blank">mountain</a> range) to an area of low altitude (like an ocean). <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/05/sodium.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="plant that life in river" border="0" src="https://3.bp.blogspot.com/-a4ecoS5DFiQ/WK2mvpsOHyI/AAAAAAAAdjc/WBnILg3M044AaxKjkJKnTd19ZNdRI5iFACLcB/s1600/plant-river.jpg" title="plant that life in river" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">plant that life in river</td></tr>
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Usually, the water flows quickly initially and slows as it moves downstream. Streams often join rivers, so there is more water at the end of a river than at the beginning. As rivers flow, they erode (wear away) rocks and pick up sediments, making <a href="http://watersome.blogspot.com/2012/09/rivers.html" target="_blank">rivers</a> often murkier at the end. <br />
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Because rivers and streams change so much from their beginnings to their ends, there are many different types of habitats for animals. As a result, the number of animal species that live in rivers and streams is greater than the number of species that live in lakes and ponds.<br />
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<i>Plant life in rivers and streams </i><br />
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A major challenge facing plants that live in rivers and streams is staying in place, especially in swift currents. Plants have several different techniques to overcome the drag (the pull) of the water. Diatoms are a type of algae. <br />
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Algae are <a href="http://watersome.blogspot.com/2011/11/marine-archaeology.html" target="_blank">marine</a> organisms that range in size from microscopic <a href="https://www.amazon.com/gp/product/B003XDI3NC/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B003XDI3NC&linkId=0d289b849d72b551133ac1a7e197154d" rel="nofollow" target="_blank">phytoplankton</a> to giant kelp and that contain chlorophyll, the same pigment used by land plants to perform photosynthesis. Diatoms avoid currents by using their small size. They grow in a single layer on the surfaces of rocks. <br />
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Because of the friction between the rock surface and the water, the water flow slows nearly to a stop within about a tenth of an inch (one-quarter of a centimeter) from the rock’s surface. This region is called the boundary layer, and it provides the diatoms with protection from the forces of the current that would otherwise drag them downstream.<br />
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Typical large river plants include algae, <a href="http://lifeofplant.blogspot.com/2011/03/mosses.html" rel="nofollow" target="_blank">mosses</a>, and liverworts. These plants overcome the drag of the water by using special adaptations to grip rocks. Large <a href="http://lifeofplant.blogspot.com/2011/10/brown-algae.html" target="_blank">algae</a> often attach themselves to rocks with root-like structures called holdfasts. In addition, plants often anchor themselves in nooks between rocks or where waters pool, to avoid the drag of the river water.<br />
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River plants that live within the currents have developed techniques to withstand the forces of the water. These forces would quickly snap any plant with rigid stems or leaves. As a result, plants that live in rivers are very flexible so that they can easily bend and move with the currents.<br />
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<i>Animal life in rivers and streams </i><br />
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Animals that live in rivers and streams also face the challenge of staying where they are. Many animals have hooks and suckers that they use to attach themselves to rocks. Blackfly larvae that live in streams in the northern United States and Southern <a href="http://historysome.blogspot.com/2012/02/canada-nunavut-territory.html" target="_blank">Canada</a> have suction cups that they use to stick to rocks in streams. Mayfly larvae have hooks that they use to fasten themselves to the algae growing on rocks.<br />
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Other animals have streamlined shapes that minimize drag by presenting little resistance to water. Trout, which are extremely common in oxygen-rich fast-flowing waters, are shaped like torpedoes. Limpets are flattened molluscs that cling to the surfaces of rocks. Their flat shape decreases the currents’ drag on them.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/05/sore-throat.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="some trouts in river stream" border="0" src="https://4.bp.blogspot.com/-ft92oasnp2o/WK2oXVPJFOI/AAAAAAAAdjo/J90obkDBD_Q6MFdIr3Y3j4HcIK_zh1HaQCLcB/s1600/trout-river.jpg" title="some trouts in river stream" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">some trouts in river stream</td></tr>
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Animals that live in streams and rivers have developed interesting ways of gathering food in the fast-flowing waters. Snails, limpets, and caddis fly larvae scrape algae from rocks using special mouthparts. Many different insect larvae, as well as freshwater clams, filter the water for small bits of food. <br />
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They have specialized mouthparts that look like brushes or combs that they use to strain the water and extract the edible plankton (animals and plants that float with currents) that float into their reach.<br />
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Rivers and streams are homes to a large number of fish. Perch, smallmouth bass, <a href="http://identifyfish.blogspot.com/2010/11/florida-largemouth-bass-micropterus.html" target="_blank">largemouth bass</a>, <a href="http://identifyfish.blogspot.com/2010/11/black-bullhead-ameiurus-melas.html" target="_blank">bullhead</a>, <a href="http://identifyfish.blogspot.com/2010/11/common-carp-cyprinus-carpio.html" target="_blank">carp</a>, <a href="http://identifyfish.blogspot.com/2010/11/northern-pike-esox-lucius.html" target="_blank">pike</a>, and <a href="http://identifyfish.blogspot.com/2010/11/green-sunfish-lepomis-cyanellus.html" target="_blank">sunfish</a> prefer the parts of rivers where waters slow. These fish tend to be large, visual predators (animal that hunts another animal for food) that hunt in pools for smaller fish and invertebrates (animals without a backbone). <br />
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Sculpins and darters prefer the faster moving sections of the river where waters are highly oxygenated. They use the swift current to bring food to them rather than hunting for their prey. Trout are also found in these faster moving parts of the river.<br />
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<b>Life in Lakes and Ponds</b><br />
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Large lakes are often divided into zones. The near-shore area is called the littoral zone. This is the part of the lake that is shallow enough for aquatic plants to grow. The limnetic zone, also called the epilimnion, is the surface water of the lake away from the shore. (The prefix epi means “on the surface” and the root word limn means “lake.”) <br />
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It extends down as deep as sunlight penetrates. The majority of the plant life in this zone is phytoplankton (microscopic plants that float in currents). The deep part of the lake is called the profundal zone or the hypolimnion. (The prefix hypo means “under.”) No plant life exists in this zone because of the absence of light. Most of the biological activity is that of bacteria decomposing dead animals and plants.<br />
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<i>Seasonal Changes in Lakes</i><br />
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Lakes and ponds are greatly influenced by the temperature changes throughout the seasons. The description below is typical for a lake in a temperate (moderate) climate, which experience seasonal temperature changes. Tropical lakes (those in hot and humid areas) will have less dramatic fluctuations in temperatures.<br />
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In the <a href="http://identifyfish.blogspot.com/2010/10/summer-flounder-paralichthys-dentatus.html" target="_blank">summer</a>, the Sun warms the epilimnion. Warmer water is less dense than colder water, so it floats on top of the cooler water in the hypolimnion. The region between the warm surface waters and the cold deeper waters is a transition zone where the water changes temperature very quickly with depth. <br />
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This region is called the thermocline. The thermocline acts as a kind of barrier between the surface and the deep waters. In the early summer, the epilimnion is full of life. <br />
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Phytoplankton can grow quickly because they have plenty of light and nutrients and the water temperature is warm. In turn, <a href="https://www.amazon.com/gp/product/B004YLJWPK/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B004YLJWPK&linkId=85b47f3aa5abff839a947db98a080b1a" rel="nofollow" target="_blank">zooplankton</a> (animals like crustaceans and small fish that float in the waters) feed on the phytoplankton. These zooplankton are food for larger fish and birds.<br />
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As summer progresses, the phytoplankton use up the nutrients in the epilimnion. They begin to die and sink to the bottom of the lake. There, decomposers, like <a href="http://lifeofplant.blogspot.com/2011/04/fungi.html" target="_blank">fungi</a> and bacteria, break up the dead phytoplankton and animals and convert them into the nutrients that phytoplankton need to grow. <br />
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Because the thermocline acts as a barrier between the bottom and the top of the lake, these nutrients are unavailable to the phytoplankton in the epilimnion. Phytoplankton cannot grow in the hypolimnion, where there are nutrients, because there is no light.<br />
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In the fall, the air temperature cools, which cools the surface of the lake. Eventually the temperature in the epilimnion becomes the same temperature as that of the hypolimnion. The thermocline disappears and the nutrient-rich waters from the hypolimnion mix with the waters in the surface of the lake. <br />
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This is called the fall turnover. At this time, the nutrients from the bottom of the lake are mixed throughout the lake. However, because the amount of sunlight decreases in the fall and into the <a href="http://identifyfish.blogspot.com/2010/10/winter-flounder-pseudopleuronectes.html" target="_blank">winter</a>, the phytoplankton in the surface cannot grow very quickly.<br />
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During the winter, the surface of the lake continues to cool. Freshwater is densest at 39°F (4°C). Ice, with a temperature of 32°F (0°C), is less dense than the deeper waters and so it forms on the surface of the lake. <br />
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This provides fish and other invertebrates room to live under ice-covered lakes. The ice also acts an blanket-like insulation that helps keep the water underneath from freezing. <br />
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In the springtime, the temperatures warm so the ice melts. Eventually the whole lake becomes 39°F (4°C) and so the waters from the bottom mix with the waters from the surface. This is called the spring turnover. As summer begins, the surface waters warm and the thermocline again separates the epilimnion from the hypolimnion. <br />
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Because of the fall and spring turnovers, the nutrients from the bottom of the lake are available to the phytoplankton in the surface waters. This sets the lake up for the summer’s rapid growth of phytoplankton and all the animals that depend on them.<br />
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Plant Life in Lakes and Ponds Some of the most plants in lakes and ponds are the smallest. These phytoplankton are usually single-celled plants grouped with the algae. Sometimes they connect themselves together into long strings called colonies. <br />
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Common phytoplankton in lakes and ponds are diatoms, which have beautiful shells made of silica (the same material that comprises sand); <a href="http://lifeofplant.blogspot.com/2011/04/dinoflagellates.html" target="_blank">dinoflagellates</a>, which move by snapping their flagella (long whip-like cell extensions that can propel an organism; and cyanobacteria, which are bacteria that perform photosynthesis.<br />
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The larger plants in ponds and lakes include large algae and mosses, cattails, reeds, water lilies, bladderworts, willows, and button bush. These plants often grow in mud where the gases that they need to grow—such as oxygen and carbon dioxide— are scarce. Many larger plants have stems that are spongy and they pull gases from the air down into their roots.<br />
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Plants on land use their roots to gather water and nutrients, however aquatic plants are surrounded by water, and nutrients are dissolved in the water. Some aquatic plants have given up their roots. <br />
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For example, duckweed (or water lentil) and watermeal are small pea-sized plants that float on the surface of lakes and ponds in the spring and summer. They absorb nutrients from the water and produce a lot of starches. <br />
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By the fall, they are so heavy with nutrients that they sink to the bottom of the lake. They live out the winter in the mud at the bottom of the lake, existing on their stores of starch. By spring, they have used up so much of the starch, they are light enough to float again. <br />
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They pop to the surface just in time to use the strong light of spring and summer for photosynthesis and they begin to use their starch stores once again. Other large plants, like milfoil, water soldier, and water hyacinths also float on the surface of lakes and ponds.<br />
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The edges of lakes are often divided into four zones based on the physical environment and the types of plants found there. Beginning farthest from the water, the swamp plant zone contains plants that have roots in the shallow water. <br />
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At times the water can recede from this zone, leaving the plants roots exposed to the air. Typical plants in the swamp plant zone are rushes and sedges (a type of plant that looks like a stiff grass). The next zone is called the floating-leaf and emergent zone. <br />
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Here the water never dries up, but the lake is shallow enough that the tops of plants emerge out of the water. A typical plant that lives in this zone is the water lily, which has special gas filled chambers in its leaves that allow it to stay floating on the surface of the water. <br />
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In the submerged plant zone, plants live entirely underwater. Canadian waterweed and many types of mosses live in this zone. The freefloating plant zone takes up the center of the lake. Here plants without roots, like duckweed and water soldier, float freely on the surface.<br />
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<i>Animal life in lakes and ponds </i><br />
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Zooplankton float in the epilimnion of lakes and eat phytoplankton and other zooplankton. Usually, these animals are nearly transparent, in order to avoid being seen by their predators. <br />
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Typical zooplankton in lakes include the water flea, Daphnia, which can reproduce without mating. Under normal conditions all of its offspring are female. However, when the animals are stressed, by lack of food for example, they will produce males. <br />
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This mixes up the gene pool of the population and creates individuals that are likely to withstand environmental changes. Another typical freshwater zooplankton is the rotifer, which has bristles on top of its head that it whirls like propellers in order to move through the water and capture prey.<br />
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Many insects have juvenile stages that are aquatic. Mayflies, caddis flies, mosquitoes, and dragonflies all live for some period underwater in lakes and ponds. They swim among the rocks and plants in the lake bottom for a season or several years. <br />
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Then they metamorphose (change in appearance) into their adult form and fly away from the water. The bottom of the lake is also home to many different worms, mussels, and <a href="https://www.amazon.com/gp/product/B00D7Q3FTW/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B00D7Q3FTW&linkId=ecbd2cddc0876aab3ab14bedaee14f64" rel="nofollow" target="_blank">crustaceans</a>. These animals feed on the remains of plants and animals that drop to the bottom of the lake from above.<br />
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Larger animals live in lakes and ponds. In particular, fish, birds, and amphibians prey on the invertebrates that live in the lakes. Fish such as bluegills eat juvenile insects that swim in the bottom of the lake, while crappies eat zooplankton near the surface. <br />
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Birds like flycatchers and warblers fly near the surface of lakes, preying on insects that are hatching from their juvenile stage. <a href="https://www.amazon.com/gp/product/0823411346/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=0823411346&linkId=1656ebbae0aa61b6223a76f28d7101f9" rel="nofollow" target="_blank">Frogs</a> also hunt for insects that live near the pond. <br />
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Still other birds and fish prey on smaller fish. Bass, <a href="http://identifyfish.blogspot.com/2010/09/chum-salmon-oncorhynchus-keta.html" target="_blank">salmon</a>, osprey, loons, and heron hunt for fish by using their keen eyesight. Beavers and muskrats are mammals that depend on water for their homes. They build dams and lodges, which provide them with protection from predators.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-46212277958392777122012-09-30T10:32:00.002+07:002017-02-23T14:56:22.826+07:00Groundwater Formation<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/06/rhubarb-root.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Groundwater Formation" border="0" src="https://2.bp.blogspot.com/-BKypTZ0bDOY/UGe86nmKL0I/AAAAAAAADfw/yemIA5n2mN4/s1600/aquifer.gif" title="Groundwater Formation" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Groundwater Formation</td></tr>
</tbody></table>
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Groundwater is <a href="https://www.amazon.com/gp/product/B01M3X6XFJ/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B01M3X6XFJ&linkId=fa6ef1fdba462acb78866e746f852152" rel="nofollow" target="_blank">fresh water</a> in the rock and soil layers beneath Earth’s land surface. Some of the precipitation (rain, snow, sleet, and hail) that falls on the land soaks into Earth’s surface and becomes groundwater. Water-bearing rock layers called aquifers are saturated (soaked) with groundwater that moves, often very slowly, through small openings and spaces. <br />
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This groundwater then returns to lakes, streams, and marshes (wet, low-lying land with grassy plants) on the land surface via springs and seeps (small springs or pools where groundwater slowly oozes to the surface). <br />
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Groundwater makes up more than one-fifth (22%) of Earth’s total fresh water supply, and it plays a number of critical hydrological (water-related), geological and biological roles on the continents. Soil and rock layers in groundwater recharge zones (an entry point where water enters an aquifer) reduce flooding by absorbing excess runoff after heavy rains and spring snowmelts. <br />
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Aquifers store water through dry seasons and dry weather, and groundwater flow carries water beneath arid (dry) deserts and semi-arid grasslands. Groundwater discharge replenishes streams, lakes, and <a href="http://watersome.blogspot.com/2012/09/wetlands.html" target="_blank">wetlands</a> on the land surface and is especially important in arid regions that receive limited rainfall. <br />
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Flowing groundwater interacts with rocks and minerals in aquifers, and carries dissolved rock-building chemicals and biological nutrients. Vibrant communities of plants and animals (<a href="http://lifeofplant.blogspot.com/2011/04/ecosystems-studies.html" target="_blank">ecosystems</a>) live in and around groundwater springs and seeps.<br />
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Almost all of the fresh liquid water that is readily available for human use comes from underground. (The bulk of Earth’s fresh water is frozen in ice in the North and South Pole regions. Water in streams, rivers, lakes, wetlands, the atmosphere, and within living organisms makes up only a tiny portion of Earth’s fresh water.) <br />
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For thousands of years, humans have used groundwater from springs and shallow wells to fill drinking water reservoirs, and water livestock and crops. Today, human water needs far exceed surface water supplies in many regions, and Earth’s rapidly-growing human <a href="http://be-eco-friendly.blogspot.com/2010/10/population.html" target="_blank">population</a> relies heavily upon groundwater to meet its ever larger demand for clean, fresh water.<br />
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<b>Aquifers: Fresh Water Underground</b><br />
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An aquifer is a body of rock or soil that yields water for human use. Most aquifers are water-saturated layers of rock or loose sediment. With the exception of a few aquifers that have water-filled caves within them, aquifers are not underground <a href="http://watersome.blogspot.com/2012/09/lakes.html" target="_blank">lakes</a> or holding tanks, but rather rock “sponges” that hold groundwater in tiny cracks, cavities, and pores (tiny openings in which a liquid can pass) between mineral grains (rocks are made of minerals). <br />
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<a href="http://abouthealthsome.blogspot.com/2016/06/rhus-toxicodendron.html" imageanchor="1" rel="nofollow" style="margin-left: 1em; margin-right: 1em;" target="_blank"><img border="0" src="https://1.bp.blogspot.com/-07dNiSFWNmY/UGe9INBA_II/AAAAAAAADf4/Akfi6aFQG70/s1600/groundwater-formation.gif" /></a></div>
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The total amount of empty pore space in the rock material, called its porosity, determines the amount of groundwater the aquifer can hold. Materials like sand and gravel have high porosity, meaning that they can absorb a high amount of water. Rocks like granite, marble, and limestone have low porosity, and make poor groundwater reservoirs.<br />
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Aquifers must have high permeability in addition to high porosity. Permeability is the ability of the rock or other material to allow water to pass through it. The pore space in permeable materials is interconnected throughout the rock or <a href="http://watersome.blogspot.com/2011/11/sediment-contamination.html" target="_blank">sediment</a>, allowing groundwater to move freely through it. Some high-porosity materials, like mud and clay, have very low permeability. <br />
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They soak up and hold water, but don’t release it easily to wells or other groundwater discharge points, so they are not good aquifer materials. Sandstone, limestone, fractured granite, glacial sediment, loose sand, and gravel are examples of materials that make good aquifers.<br />
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Water enters aquifers by seeping into the land surface at entry points called recharge zones and leaves at exit points called discharge zones. (Some aquifers discharge into the ocean.) <br />
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Influent or “ water-losing” streams, ponds, or lakes are bodies of surface water in recharge zones that contribute groundwater from their water supply. Groundwater flows into effluent or “water-gaining” streams and ponds in discharge zones.<br />
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For the water level in an aquifer to remain constant, the amount of water entering at recharge zones must equal the amount leaving at discharge zones. (Imagine a bucket punched with holes under a dripping faucet. If water drips in at the same rate that it drips out, the water level stays the same.) <br />
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If water discharges or is pumped from an aquifer more quickly than it recharges, the groundwater level (water table) will fall. The time an average water molecule spends within an aquifer is called its residence time. <br />
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Water in some fast-flowing aquifers spends only a few days underground, while other rock layers can hold water for ten thousand years. Average aquifers have residence times of about two hundred years.<br />
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<i>The water table and unconfined aquifers </i><br />
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Water enters aquifers by moving slowly down through a layer of surface rocks and <a href="http://be-eco-friendly.blogspot.com/2010/09/soil-pollution.html" target="_blank">soil</a> whose pore spaces are partially filled with air (zone of infiltration). The water continues moving downwards until it reaches a level where all the pore spaces are completely filled with water (zone of saturation). <br />
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The top of the zone of saturation is called the water table. In some wet, lowland regions, southern <a href="http://identifyfish.blogspot.com/2010/11/florida-largemouth-bass-micropterus.html" target="_blank">Florida</a> for example, the water may be only a few feet (meters) below the surface. In others, like the American Southwest, water-saturated rocks may be hundreds of feet below the land surface.<br />
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Groundwater reservoirs that have uniform rock or soil properties (porosity and permeability) throughout are called unconfined aquifers. The water table forms the upper surface of an unconfined aquifer. The shape of the water table in an unconfined aquifer mirrors the shape of the land surface, but its slopes are gentler. <br />
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In temperate (moderate) climates that receive moderate amounts of groundwater-replenishing rainfall, water infiltrates into unconfined aquifers in hilltop recharge zones and discharges into effluent streams and <a href="http://watersome.blogspot.com/2012/09/ponds.html" target="_blank">ponds</a> in low areas where the water table intersects the land surface. Water will only rise to the level of the water table in a well, so a pump or bucket is required to extract water from an unconfined aquifer.<br />
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<i>Confined aquifers and artesian flow </i><br />
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Confined aquifers are pressurized groundwater reservoirs that lie beneath layers of non-permeable rock (granite, shale) or sediment (clay). Groundwater enters a confined aquifer in recharge zones beyond the uphill edges of the confining layer and discharges beyond the downhill edges. <br />
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Groundwater trapped beneath an impermeable barrier cannot rise to the height of the water table, so pressure builds up in confined aquifers. Artesian wells are wells drilled in confined aquifers where the pressure is great enough to make water flow at the surface.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-43070236618918698282012-09-29T21:40:00.001+07:002017-02-23T16:10:22.539+07:00Lakes<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/06/rhinitis.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Lake" border="0" src="https://2.bp.blogspot.com/-XJKY9xoJSEA/WK6Y8fitO_I/AAAAAAAAdko/-V_9amux39UunmpetkLzR7Xuu4vuNcrGACLcB/s1600/lake.jpg" title="Lake" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Lake</td></tr>
</tbody></table>
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Lakes are large inland bodies of fresh or saline (salty) water. Lakes form in places where water collects in low areas or behind natural or man-made dams (barriers constructed to contain the flow of water). <br />
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Some lakes are fed by streams (natural bodies of flowing freshwater), and some form where groundwater (water flowing in rock layers beneath the land surface) discharges onto the land surface. <br />
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Water leaves lakes by flowing into outlet streams, infiltrating (soaking in) into groundwater reservoirs called aquifers, and by evaporating into the atmosphere (mass of air surrounding Earth). Lakes vary in size from large lakes such as the Great Lakes of <a href="http://epicworldhistory.blogspot.com/2012/05/natives-of-north-america.html" rel="nofollow" target="_blank">North America</a>, to small mountain lakes. <br />
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Lakes are larger than ponds, which are small bodies of fresh water that are shallow enough for rooted plants to grow. The study of ecology (relationships between living organisms and their environment) in lakes, inland seas, and wetlands is called <a href="http://watersome.blogspot.com/2011/11/limnology.html" target="_blank">limnology</a>.<br />
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Lakes store only a tiny percentage of Earth’s fresh water. They are, however, an extremely important water resource for humans. Freshwater lakes provide water for <a href="http://watersome.blogspot.com/2011/11/agricultural-water-use.html" target="_blank">agricultural</a> irrigation (watering), industrial processes, municipal uses, and residential water supplies. <br />
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People who live in the continental interiors use lakes for fishing and recreation, and very large lakes have important <a href="http://watersome.blogspot.com/2011/11/shipping-on-freshwater-waterways.html" target="_blank">shipping</a> and transportation routes. Humans also construct artificial lakes, called reservoirs, by building dams across rivers. <br />
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In addition to providing the benefits of natural lakes, reservoirs also store water for specific communities, control <a href="http://watersome.blogspot.com/2012/09/floods-and-flood-control.html" target="_blank">floods</a>, and generate hydroelectricity (electricity generated from water power).<br />
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<b>How lakes form and disappear</b><br />
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Earth scientists who study water on the continents (hydrologists and hydrogeologists) see lakes as temporary reservoirs within stream and groundwater systems. <br />
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All water that falls as precipitation (rain, snow, sleet, hail) on the land surface of continents eventually makes its way to the <a href="http://be-eco-friendly.blogspot.com/2010/10/ocean-dumping.html" rel="nofollow" target="_blank">ocean</a> or evaporates back into the atmosphere. <br />
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Water collects in lakes because it enters more rapidly than it escapes, but it is never permanently trapped there. As in a tub with a running faucet and an open drain, individual water molecules (smallest unit of water, each containing two hydrogen atoms and one oxygen atom) are constantly entering and escaping. <br />
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After arriving in a lake, an average water molecule spends about one hundred years before moving to a new reservoir. (The time that an average water molecule spends in a reservoir is called it residence time. <br />
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Water resides for about two weeks in rivers, forty years in <a href="http://watersome.blogspot.com/2012/09/glaciers.html" target="_blank">glaciers</a> (slow moving mass of ice), and between two hundred and ten thousand years in groundwater reservoirs.)<br />
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To geologists (Earth scientists), lakes are temporary features. Stream-fed lakes within stream systems are destined for destruction. Every stream seeks to create a constant slope, called a graded profile, between where the stream’s waters begin and ends by eroding (wearing away) and depositing <a href="http://watersome.blogspot.com/2011/11/sediment-contamination.html" target="_blank">sediment</a> (particles of sand, silt, and clay) along its course. <br />
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When a natural or man-made obstruction blocks a stream, such as a river, streams deposit sediment in the lake or reservoir behind the obstruction and erode away in front of it. <br />
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Eventually, the dam will collapse, and the lake will empty. Lakes that fill depressions and have no outlets fill when the regional climate becomes wetter or when warm periods melt mountain snows and glacial ice. <br />
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They evaporate away during periods of dry weather and dryer climate. It may take thousands, or even tens of thousands of years, but lakes eventually drain, collapse, or dry up.<br />
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<b>Lake layers and overturns</b><br />
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Contrary to their common image as evenly mixed pools of unmoving water, lakes are <a href="http://trytostayhealthy.blogspot.com/2010/12/vitamin-b-complex.html" target="_blank">complex</a>, dynamic bodies of moving surface water. Lake water varies within the lake; its temperature, chemical content, light infiltration, and biological habitats vary from top to bottom and side to side. <br />
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Furthermore, the vertical layering (stratification), horizontal variations, and circulation patterns within lakes change over time. Waves, currents (a moving mass of water), and even tides affect circulation of water within lakes.<br />
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Lakes are thermally stratified (layered according to temperature); they have layers of warm and cool water that are separated by layers where the temperature changes (thermoclines). Like the <a href="http://watersome.blogspot.com/2011/11/shipping-on-oceans.html" target="_blank">oceans</a>, many lakes have a thin layer of warm surface water, and a thicker layer of cool deep water that is separated by a thermocline layer. <br />
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Wind generates currents on lake surfaces and creates some mixing. Unlike the oceans, however, many lakes have seasonal overturns that mix their waters. water is denser than solid water (ice). Water reaches its maximum density at 39°F (4°C). <br />
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Because of this odd property, the warm less-dense water rises, the cool denser water sinks, ice floats, and lakes overturn. Lakes that are ice-covered for part of the year undergo overturns that partially or completely mix their waters.<br />
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Many lakes in temperate (moderate temperatures) regions like the northern United States overturn and mix completely twice a year (dimictic lakes). During the warm <a href="https://www.amazon.com/gp/product/B0015DYIL8/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B0015DYIL8&linkId=8d2551f35a81bc1c4135a1fa63c1fb0c" rel="nofollow" target="_blank">summer months</a>, these lakes have a usual temperature profile with warm surface waters, a thermocline, and cool bottom water. <br />
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In the fall, when the surface water cools down to 39°F (4°C), it becomes denser than the water underneath it and the surface layer sinks to the bottom. The bottom water rises to the surface, and the lake overturns. <br />
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Over the winter, the bottom water is the warmest, and the frozen surface water is the coldest. (Plants and animals survive the winter on the lake floor in the chilly, but not frozen, bottom water.) In the spring, when the ice melts, and the water warms to 39°F (4°C), it sinks, and the lake overturns again.<br />
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Limnologists classify lakes according to the number of mixing events they undergo each year. Lake type classifications have the root term mictic, meaning “to mix,” and include:<br />
<ul>
<li><b>Oligomictic</b>: Warm, ice-free lakes that rarely mix. They are warmest at the top, and coolest at the bottom. Tropical, oligomictic lakes have warm bottom water and very warm surface water. They rarely overturn because their water does not near 39°F (4°C).</li>
<li><b>Meromictic</b>: Warm, ice-free lakes that mix incompletely. These are deep lakes that are warmest at the top, and coolest at the bottom.</li>
<li><b>Monomictic/dimictic/polymictic</b>: Lakes with seasonal ice covers that overturn and mix completely once (monomictic), twice (dimictic), or many times per year (polymictic). Lake overturns are the norm in temperate regions, but local conditions affect the timing and number of overturns in specific lakes.</li>
<li><b>Amictic</b>: Lakes that never overturn because they are ice-covered throughout the year. These lakes exist near the North and South Poles and atop very high mountains. They have cold bottom water that hovers near 39°F (4°C) and frozen surface water. </li>
</ul>
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<b>Lake chemistry: saline lakes</b><br />
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Many of Earth’s largest and most important lakes contain salt water. All surface water contains some dissolved chemicals, called salts. <a href="http://watersome.blogspot.com/2011/11/surface-and-groundwater-use.html" target="_blank">Groundwater</a>, streams, and freshwater lakes all contain the chemical components of rocks and minerals. Humans can drink fresh water because our bodies can use or at least tolerate the types and concentrations of dissolved chemicals it contains. <br />
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Salt water, on the other hand, has a very high <a href="http://amazingrainbow.blogspot.com/2009/10/your-power-of-real-concentration.html" rel="nofollow" target="_blank">concentration</a> of dissolved salts, and is undrinkable. The <a href="https://www.amazon.com/gp/product/B00XTAFYKY/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B00XTAFYKY&linkId=1448157d07b0c997525f107497aaa8d7" rel="nofollow" target="_blank">Dead Sea</a>, on the border between Israel and Jordan, is Earth’s saltiest body of water. It is truly a dead sea because it is too salty to support life.<br />
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Saline lakes generally form in arid (dry) regions where surface water evaporates quickly. When water evaporates, the salts stay behind. Over time, the lake water becomes saltier. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/06/rolfing.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Great Salt Lake" border="0" src="https://1.bp.blogspot.com/-ai9lHVgPDvU/WK6g5VVk6LI/AAAAAAAAdk4/gTmW0d1X7GI_TZFzLWuKH8529mHh04STACLcB/s1600/salt-lake.jpg" title="Great Salt Lake" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Great Salt Lake</td></tr>
</tbody></table>
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Some saline lakes, such as the <a href="https://www.amazon.com/gp/product/087421436X/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=087421436X&linkId=691a3756d6cb3c8fb82346dc208bbd5b" rel="nofollow" target="_blank">Great Salt Lake</a>, are all that remains of a much larger fresh water lake that has evaporated over time. Others, like the Caspian Sea in central Asia, began as saltwater filled <a href="http://be-eco-friendly.blogspot.com/2010/10/ocean-dumping.html" target="_blank">ocean</a> basins that have since closed.<br />
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Saline lakes are often temporary features that fill during periods of wetter climate and then dry up when stream flow or groundwater discharge slows. Playa lakes are flat desert basins that occasionally fill with water. <a href="http://be-eco-friendly.blogspot.com/2011/01/desert-pupfish.html" target="_blank">Desert</a> oases (watering holes) form and disappear with such regularity that thirsty travelers think they imagined them. <br />
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The Great Salt Lake, <a href="http://amzn.to/2kPitCR" rel="nofollow" target="_blank">Caspian Sea</a>, Aral Sea, and Dead Sea are all presently evaporating. Over time, the dissolved chemicals become so concentrated in drying lakes that they bond together and form solid salt crystals. Thick layers of salt cover dry lake beds.<br />
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<b>Lake biology</b><br />
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Lakes support rich communities of plants and animals (ecosystems) that have adapted to live within ever-changing conditions on lake beds, within the water column (water running from the surface to the lake floor, often showing differences in temperature, nutrients, etc.), and along lake shores. <br />
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Lakes, like islands, are often closed systems that only rarely gain new species or individuals from other lakes. Many lakes host groups of rare species that have evolved (changed over time) together in their specific lake. <br />
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These ecosystems are rich and unique, but fragile. They have little defense against foreign predators or diseases. Human alterations and <a href="http://watersome.blogspot.com/2011/11/water-pollution.html" target="_blank">water pollution</a> have threatened many lake species. <br />
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Environmental groups and government agencies are presently attempting to protect and revive threatened lake species such as cichlids (rare doublejawed fish) that inhabit the lakes of the <a href="https://www.amazon.com/gp/product/B007OYOQKA/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B007OYOQKA&linkId=db979c18c81ba70b774a54dd8417947d" rel="nofollow" target="_blank">Great Rift Valley</a> in east Africa.<br />
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Lake organisms live in zones that are determined by the physical structure of their lakes such as the amount of available light, water depth, and distribution of nutrients. Most lake plants and animals live in shallow, well-lit surface waters called the euphotic zone. <br />
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Most plants depend on the Sun’s <a href="http://be-eco-friendly.blogspot.com/2010/01/solar-energy-basic-facts.html" target="_blank">energy</a> to produce food by the chemical process of photosynthesis, and they cannot grow in water that is too deep or too cloudy for light to penetrate. Lake animals such as fish need oxygen that plants give off during photosynthesis, so they live mostly in the euphotic zone as well. <br />
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Plants with roots grow in shallow water along edges of lakes where light reaches the lake floor (littoral zone) and floating plants perform <a href="http://lifeofplant.blogspot.com/2011/03/photosynthesis.html" target="_blank">photosynthesis</a> in the open surface waters (limnetic zone). Oxygen-consuming bacteria inhabit the deepest, darkest parts of lakes (benthic zone) where dead plant and animal materials accumulate.<br />
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Limnologists also classify lakes by the balance of organisms and nutrients in their waters. Types include lakes that are described as oligotrophic, eutrophic, and mesotrophic.<br />
<ul>
<li>Oligotrophic: Nutrient poor lakes that support very few plants and animals. Oligotrophic lakes are typically cool, deep, and have very clear water. Very little organic (relating to or from living organisms) mud accumulates in oligotropic lakes, and they often have sand and gravel beds.</li>
<li>Eutrophic: Lakes rich in plant nutrients that support abundant plant life in their surface waters. Their water is often clouded by microscopic plants, and their beds covered with thick layers of decaying plant material. Bacteria that live on the organic mud use up oxygen, and eutrophic lakes often have oxygen-poor deep water. Plants and bacteria eventually take over eutrophic lakes. They become oxygen-poor bogs and marshes where fish cannot live. Some chemicals that humans use, including fertilizers and detergents, cause a process called eutrophication when they run off into lakes, which causes the population of plants to increase to such an extent that eventually oxygen-starved fish die.</li>
<li>Mesotrophic: Lakes with moderate amounts of nutrients and healthy, balanced communities of plants, animals and bacteria. Mesotrophic lakes receive adequate amounts of fresh water and nutrients, and seasonal overturns allow nutrient-poor and nutrient-rich layers to mix. Mesotrophic lakes are intermediate between crystal-clear, lifeless oligothrophic lakes and cloudy, muddy eutrophic lakes.</li>
</ul>
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<b>Where lakes form: lake basins</b><br />
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Lakes form where water collects in depressions, or basins. Many lakes fill low areas created by plate tectonic movements (tectonic basins) and volcanic activity. (Plate tectonics is the movement of large, rigid pieces of Earth’s outer rock shell called the lithosphere.) <br />
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Retreating glaciers and ice sheets leave behind large basins and small depressions that fill with melt water. Though flowing streams and rivers generally act to fill in and drain lake basins, other sedimentary processes can create landscape depressions and natural dams that confine water in lakes.<br />
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<i>Lakes in tectonic basins </i><br />
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Rift valley lakes fill long, linear valleys within rift zones. (Rifts are areas where the continental lithosphere is stretching and beginning to break into pieces. <br />
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They are the precursors of ocean basins.) A chain of large lakes including Tanganyika, Naiveté, and Malawi follows the Great Rift Valley through eastern <a href="http://epicworldhistory.blogspot.com/2012/07/portuguese-in-africa.html" target="_blank">Africa</a>. Lake Victoria, the world’s second-largest lake, lies between two branches of the rift valley. <br />
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The Red Sea, Sea of Galilee, Dead Sea, and Gulf of Ababa fill the northern branches of the rift where it crosses the <a href="https://www.amazon.com/gp/product/1786571048/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=1786571048&linkId=1e2f516007ef47f68e6cfd031965d8ab" rel="nofollow" target="_blank">Arabian Peninsula</a> in the Middle East. Russia’s Lake Baikal, the world’s deepest lake, fills an ancient, inactive rift valley in central Asia.<br />
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Lakes also form in places where continents are moving toward each other. The Black Sea, Caspian Sea, and Mediterranean Seas fill a closing ocean basin between Africa and Europe. <br />
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When continents collide, water fills depressions in the landscape over folded and broken (faulted) rock layers that were caught between the land masses. Slopes that are too steep collapse and block rivers with natural dams. Blocks of uplifted, erosion-resistant rock form bedrock that holds back <a href="http://identifyfish.blogspot.com/2010/10/mountain-whitefish-prosopium.html" target="_blank">mountain</a> lakes.<br />
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<i>Volcanic lakes </i><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/06/rosacea.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Volcanic lakes" border="0" src="https://2.bp.blogspot.com/-8FZJB5cnCus/WK6h8o1p_2I/AAAAAAAAdlE/K1K8ZxRwlzsKUlo0GqVP5tA_WlmuTkFagCLcB/s1600/Volcanic-lakes.jpg" title="Volcanic lakes" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Volcanic lakes</td></tr>
</tbody></table>
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Volcanoes are mountains that form from eruptions of molten rock (lava) on the land surface. When a volcanic peak collapses into its emptied magma chamber (a pool or room of magna held under tremendous pressure within a volcano prior to a volcanic eruption), it forms a large circular <a href="http://epicworldhistory.blogspot.com/2012/05/basin-of-mexico.html" target="_blank">basin</a> called a caldera. (Craters, the small basins near the top of active volcanoes, sometimes also contain small lakes, but most significant volcanic lakes, including inaccurately-named Crater Lake, fill calderas.) <br />
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Yellowstone Lake in Wyoming and Crater Lake in Oregon are examples of caldera lakes. Volcanic ash, mud, and lava flows also create natural dams in river valleys. A dam of volcanic rock confines Lake Tahoe in a high valley of the <a href="https://www.amazon.com/gp/product/081121902X/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=081121902X&linkId=13a59f707bbfa330f990083182d3e179" rel="nofollow" target="_blank">Sierra Mountains</a> on the California-Nevada border.<br />
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<i>Glacial lakes </i><br />
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The thick continental ice sheets that covered northern North America, Europe, and Asia during the Pleistocene ice ages (a division of geologic time that lasted from two million to ten thousand years ago) left behind thousands of lake and ponds when they retreated about twenty thousand years ago. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/06/russian-massage.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Glacial lake" border="0" src="https://4.bp.blogspot.com/-gn5SlCTI7Vw/WK6jzK8KAPI/AAAAAAAAdlQ/XxSDWg6BpGY7xmLhRdiUf_gupB7GlFF1wCLcB/s1600/Glacial-lake.jpg" title="Glacial lake" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Glacial lake</td></tr>
</tbody></table>
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The weight of the ice sheets pushed down on the continents, leaving broad basins that filled with melt water when they retreated. The Great Lakes of North America (Superior, Huron, Michigan, Erie, and Ontario) formed this way. <br />
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Hundreds of lakes, such as the Winnipeg, Athabasca, Great Slave, and Great Bear cover the central and eastern provinces and territories of Canada that are still rebounding from their heavy ice load.<br />
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Advancing glaciers also pile tall ridges of sediment, called moraines, at their toes (the end of extensions of glaciers along the ground). When glaciers retreat, moraines hold back meltwater. <br />
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Small lakes and ponds also form in glacial depressions called kettles that form when blocks of ice buried in glacial sediment melt. Melting mountain glaciers feed many mountain lakes and glacial sediment traps streams and meltwater.<br />
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<i>Groundwater discharge lakes </i><br />
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Water moving through pore spaces in rock and soil layers discharges on the land surface in places where the water table (level below which pore spaces are saturated with water) intersects the land surface. <br />
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In regions with wet climates, the water table is near the land surface and ground water discharges in low spots. Groundwater chemically erodes limestone and other rocks and creates caves, cavities, sink holes, and collapse basins called karst features. Florida’s many lakes, including Lake Okeechobee, are groundwater-filled karst features.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-53852700923883423852012-09-29T17:09:00.004+07:002017-03-18T18:51:07.315+07:00Ponds<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/06/rosemary.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Pond" border="0" src="https://4.bp.blogspot.com/-s-dfcnPZGBk/WK7JNTZ6AFI/AAAAAAAAdls/c18o9dTGTvkyYwBxaEA9FQwIKwdCpOPFwCLcB/s1600/pond.jpg" title="Pond" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pond</td></tr>
</tbody></table>
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A pond is a depression in the ground that is filled with water that remains year round. Ponds range in size from the artificial backyard projects about the size of a bathtub to bodies of water that are about the size of a football field. Ponds support a variety of animal and plant life, and are also used as recreational sites by people.<br />
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The difference between a pond and a lake involves size and water depth. A lake is big enough to have at least one <a href="http://watersome.blogspot.com/2012/09/beach-erosion.html" target="_blank">beach</a> (sand or rock that slopes down to the water) and contains enough water to generate waves from the wind that blows across the surface of the water. <br />
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In contrast, a pond is usually too small for waves of any size to form. At the center of a lake, the water can reach depths of many hundreds, even thousands of feet (meters). A pond, however, is a shallow and still body of water where sunlight can usually reach down to the bottom.<br />
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<a name='more'></a><table align="center" border="0"><tbody>
<tr> <td align="center"><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/gp/product/B00OX5B8CW/ref=as_li_ss_il?ie=UTF8&linkCode=li3&tag=waterabout-20&linkId=d1630e4ffbc01947dc7a490a4a0fbf91" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=B00OX5B8CW&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=B00OX5B8CW" style="border: none !important; margin: 0px !important;" width="1" /></span><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/gp/product/B00KR63LF8/ref=as_li_ss_il?ie=UTF8&linkCode=li3&tag=waterabout-20&linkId=80f7d54590d86eedb4428e18c3a65629" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=B00KR63LF8&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=B00KR63LF8" style="border: none !important; margin: 0px !important;" width="1" /></span></td> </tr>
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<b>How ponds form</b><br />
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Natural ponds form in shallow depressions where rainwater (including runoff from nearby higher areas) collects. Water from an underground <a href="http://be-eco-friendly.blogspot.com/2010/10/nonpoint-source-pollution.html" target="_blank">source</a> such as an underground spring can also collect into a pond.<br />
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Ponds that people enjoy in their backyard are often artificial, created by preparing the hole and adding water and plants to create a backyard oasis. These ponds can provide relaxation and a habitat for attracting insects, birds, and amphibians (such as frogs and salamanders), even in backyards located in a bustling city.<br />
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Other artificial ponds are workhorses. One example is a sewage treatment pond. This type of pond keeps the sewage in a place where the growth of microorganisms can occur in the shallow and warm water. <br />
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As microorganisms such as algae grow, they can use some of the materials in the sewage as food. This helps clean the water, and is an example of bioremediation, the process of using natural substances such as bacteria, to clean a contaminated natural resource, such as water.<br />
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<b>Life in and around ponds</b><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/06/rosen-method.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img border="0" src="https://3.bp.blogspot.com/-JdZG7kFDuZM/UGbGLaVbU7I/AAAAAAAADdw/wngeEqOvQL8/s1600/pond-life.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">life in pond</td></tr>
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Ponds are havens for plants. Because the sunlight is abundant all through the water, plant can grow from every location in a pond. (Plants need sunlight to live as they convert the Sun’s energy into food in a process called <a href="http://lifeofplant.blogspot.com/2011/03/photosynthesis.html" target="_blank">photosynthesis</a>.) <br />
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Often, the surface of a pond will be almost entirely covered with pond-loving plants such as the water lily and other plants that need higher levels of sunlight or that need direct exposure to air.<br />
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Ponds also support various species of <a href="https://www.amazon.com/gp/product/075667221X/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=075667221X&linkId=2f5f3735630a1890323f880ed3f770ce" rel="nofollow" target="_blank">animal life</a>, both in and surrounding its waters. Often, the bottom of a pond will be muddy, rather than rocky, and the mud hosts a variety of living creatures, such as <a href="http://be-eco-friendly.blogspot.com/2011/01/hell-creek-cave-crayfish.html" rel="nofollow" target="_blank">crayfish</a>. <br />
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The still pond water and muddy bottom are also favorable conditions for the eggs of insects and creatures such as frogs to develop (often attached to the stems or leaves of plants). <br />
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For microscopic life such as bacteria and algae, a pond offers plenty of food and the sunlit water provides a suitable temperature for the <a href="https://www.amazon.com/gp/product/B01N0FH3RM/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B01N0FH3RM&linkId=aadddb0ea0ed8aea02948a4d24cf1b97" rel="nofollow" target="_blank">microscopic cells</a> to grow and divide. <br />
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Animals such as deer often use natural ponds as a source of <a href="https://www.amazon.com/gp/product/B004CQWWKY/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B004CQWWKY&linkId=27bf9741e821e7c3895446e888591e90" rel="nofollow" target="_blank">drinking water</a>. Birds feed upon fish that live in ponds. Beavers find the still pond waters a good place to build their lodge. <br />
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Ponds are often a source of relaxation and recreation. In warmer times of the year, a pond’s edge can be a place where people picnic or rest outdoors. In the cold winter season of northern climates, ponds can freeze solid and host winter sports such as <a href="https://www.amazon.com/gp/product/B000LE215M/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B000LE215M&linkId=9de3624e02ad21f05bd87a7db0a1a939" rel="nofollow" target="_blank">ice skating</a>.<br />
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<b>The fate of ponds</b><br />
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The flow of water into and out of a pond can be slow. This feature, along with its shallow depth, makes a pond vulnerable to <a href="http://be-eco-friendly.blogspot.com/2011/04/soil-contamination.html" target="_blank">contamination</a>. If chemicals that upset the natural composition of the pond are introduced, then the water quality necessary to sustain life can be destroyed. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://watersome.blogspot.com/2011/11/exploration-of-oceans.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Ponds in africa" border="0" src="https://1.bp.blogspot.com/-LwCmEohzbLY/WM0erjY6qlI/AAAAAAAAeqw/J2mnubcNsckTgcbhHTd2hz-dA1syRNZdgCLcB/s1600/ponds-africa.jpg" title="Ponds in africa" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ponds in africa</td></tr>
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Ponds that form in arid (dry) regions where rainfall is briefly heavy then sparse throughout the rest of the year continue a cycle of filling up, then slowly drying. These ponds attract animal life only when water is abundant, which can sometimes cause conflicts with humans. <br />
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In some regions of Africa, <a href="https://www.amazon.com/gp/product/1426319479/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=1426319479&linkId=0d91b56cbf8fa15ee002127d40c373e4" rel="nofollow" target="_blank">crocodiles</a> return during the rainy season to newly filled ponds that form near populated villages. Hungry after hibernating (being in an inactive state) the rest of the year, the crocodiles pose a threat to livestock that also drink from the pond, and the people who tend the livestock. <br />
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As time passes, the vast majority of ponds will naturally fill in, as sediment (particles of gravel, sand, and silt) and other debris collect in the <a amzn-ps-bm-asin="B01HBVI3FE" class="amzn_ps_bm_tl" data-amzn-link-id="db9b5ac842ee6db266ec4db2d43e2106" data-amzn-ps-bm-keyword="shallow water" href="http://www.amazon.com/Shallows-Blake-Lively/dp/B01HBVI3FE/ref=as_li_bk_tl/?tag=epichistory-20&linkId=db9b5ac842ee6db266ec4db2d43e2106&linkCode=ktl" id="amznPsBmLink_2750410" rel="nofollow" target="_blank">shallow water</a><img alt="" border="0" height="0" id="amznPsBmPixel_2750410" src="https://ir-na.amazon-adsystem.com/e/ir?source=bk&t=epichistory-20&bm-id=default&l=ktl&linkId=db9b5ac842ee6db266ec4db2d43e2106&_cb=1487920767383" style="border: none !important; height: 0px !important; margin: 0px !important; padding: 0px !important; width: 0px !important;" width="0" />. After about one hundred years, what was once a pond often becomes a field, and the water source of the pond is diverted by the changing landscape or by changes in rainfall amounts.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-73277312738270884992012-09-29T14:43:00.001+07:002017-02-26T19:38:02.104+07:00Rivers<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.tw/2016/07/pine-bark-extract.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Kawarau River in Queenstown" border="0" src="https://3.bp.blogspot.com/-lcgzHWWzav4/WLLDodGPN4I/AAAAAAAAdtY/AcT9U_4TFuwvFzmhobgM5XtELfwRFQ6VACLcB/s1600/river.jpg" title="Kawarau River in Queenstown" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Kawarau River in Queenstown</td></tr>
</tbody></table>
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Rivers are bodies of flowing surface water driven by gravity. Hydrologists, scientists who study the flow of water, refer to all bodies of flowing water as streams. In <a href="http://epicworldhistory.blogspot.com/2012/07/the-book-of-common-prayer.html" target="_blank">common</a> language, it is accepted to refer to rivers as larger than streams. Water flowing in rivers is only a very small portion of Earth’s fresh water. <br />
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The oceans contain about 96% of the water on Earth, and most fresh water is bound up in glacial ice near the North and South Poles. Rivers shape the landscape and are integral to the hydrologic cycle (circulation of water on and around Earth) on the continents.<br />
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Rivers shape the lands as they erode (wear away) and deposit <a href="http://watersome.blogspot.com/2011/11/sediment-contamination.html" target="_blank">sediment</a> (particles of gravel, sand, and silt) along their courses. Running river water acts to level the continents. When geologic forces slowly raise (uplift) mountain ranges, rivers wear them away. <br />
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<tr> <td align="center"><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/gp/product/1617691259/ref=as_li_ss_il?ie=UTF8&linkCode=li3&tag=waterabout-20&linkId=e3b0ad482a912100ddbe0e72229f0b23" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=1617691259&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=1617691259" style="border: none !important; margin: 0px !important;" width="1" /></span><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/gp/product/B00TFY8Z54/ref=as_li_ss_il?ie=UTF8&linkCode=li3&tag=waterabout-20&linkId=2fd5322ceb8aebe071ba51fb5698941c" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=B00TFY8Z54&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=B00TFY8Z54" style="border: none !important; margin: 0px !important;" width="1" /></span></td> </tr>
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The streams that form the Ganges River of India (headwater streams), for example, are presently tearing down the Himalayas almost as quickly as they are uplifted by the movements of Earth’s crustal plates (plate tectonics). <br />
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When geologic forces create depressions or low areas on the continents, rivers act to fill them. River sediment replenishes floodplain (Flat land next to rivers that are subject to flooding) soils and coastal sands. <br />
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Earth’s major rivers, including the Nile, Amazon, Yangtze, and Mississippi, drain the waters of vast continental areas and set down (deposit) huge deposits of sediments at the ends of rivers that flow into the ocean (for example, in deltas at the end of many rivers) Rivers host vibrant communities of plants and animals, and refill groundwater reservoirs and <a href="http://watersome.blogspot.com/2012/09/wetlands.html" target="_blank">wetlands</a> that support biological life far beyond their banks.<br />
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Rivers are a main focus of human interaction with the natural environment. Human <a href="http://lifeofplant.blogspot.com/2011/03/north-american-agriculture.html" target="_blank">agriculture</a>, industry, and biology require fresh, accessible water from rivers. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.fr/2016/07/pityriasis-rosea.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Small boat in Nile river" border="0" src="https://3.bp.blogspot.com/-DbKIPdkDjiU/WLLI8gylUaI/AAAAAAAAdtw/BJzvsILAH7w5MNqYWeKssK_mUhG90plgQCLcB/s1600/nile-boat.jpg" title="Small boat in Nile river" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Small boat in Nile river</td></tr>
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Ancient human civilizations first arose in the fertile valleys of the world’s great rivers: the Yangtze and <a href="http://identifyfish.blogspot.com/2010/11/yellow-bullhead-ameiurus-natalis.html" target="_blank">Yellow</a> Rivers in China, the Tigris and Euphrates Rivers in the Middle East, and the Nile River in Egypt. The distribution of Earth’s rivers and systems of rivers has influenced human population patterns, commerce, and conquest since ancient times.<br />
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Rivers flow through the great cities of the world, and the imagery of rivers is deeply embedded in our language, culture, and history. Today, billions of people depend directly and indirectly on rivers for food and water, transportation and <a href="http://watersome.blogspot.com/2011/11/recreation-in-and-on-freshwaters.html" target="_blank">recreation</a>, and spiritual and religious inspiration.<br />
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Almost all major rivers are today confined by man-made dams and levees (walls along the banks) that provide people with the means to generate electricity and protection from floods. These alterations to rivers have come at an environmental cost.<br />
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When floodwaters are contained by levees or other flood-control dams, they no longer supply nutrients and sediment to floodplain soils that support agriculture. Furthermore, dams and levees that upset a river’s natural path and profile (side view) cause changes to the patterns of erosion and deposition (depositing sediments) throughout the entire river system.<br />
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Dams have contributed to <a href="http://watersome.blogspot.com/2012/09/beach-erosion.html" target="_blank">beach erosion</a> on many coastlines because dams trap sediment in reservoirs. Agricultural and urban development along riverbanks has threatened many species of plants and animals that live in riverside wetlands.<br />
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Also, the very dams and levees that prevent frequent small floods create an increased risk of infrequent, disastrous flooding. The city of New Orleans, for example, lies at a lower elevation than the bed of the Mississippi River that runs through the center of the city in an artificial channel behind massive levees. If the levees failed, a flash flood would engulf the city and potentially threaten the lives of its residents.<br />
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<b>Major rivers</b><br />
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Earth’s largest river systems define the natural and human environment within their <a href="http://watersome.blogspot.com/2011/11/watersheds.html" target="_blank">watersheds</a>. A watershed is the land area that drains water into a river or other body of water. A list of the world’s major rivers is also a list of the major natural and cultural geographic regions on six continents. (The continent Antarctica is too cold for liquid water. Its fresh water is bound up in large masses of moving ice called glaciers.)<br />
<ul>
<li>Africa: The Nile is, by most measurements, the world’s longest river. (River lengths are difficult to measure because rivers constantly shift their courses and change length. <br />
There is also disagreement about which branches of water (tributaries) are considered part of the main river. By some measurements, the Amazon River in South America is actually slightly longer than the Nile.) The Nile has sustained life in the inhospitable Sahara desert of eastern Africa for thousands of years. <br />
Its headwater (uphill end) streams flow from lakes in <a href="http://earlyworldhistory.blogspot.com/2012/03/ancient-ethiopia.html" target="_blank">Ethiopia</a> and Uganda and feed two branches, the White Nile and the Blue Nile, which meet in the Sudanese city of Khartoum. From there, the Nile cuts a green-bordered lifeline through the Egyptian desert. <br />
It flows through Cairo, the bustling capital of modern-day Egypt, past the pyramids of Giza and the ancient Egyptian capital of Thebes, to its outlet in the Mediterranean Sea. The Congo River (called the Zaire River from 1971 to 1997) makes a long loop through the equatorial rainforests and war-torn nations of central western Africa.<br />
The Congo is the main trade and travel route into the African interior, and it is the setting for Joseph Conrad’s famous novel Heart of Darkness. The Limpopo, Okavango, Ubangi, and Zambezi are other major African rivers.</li>
<li>Asia: Huge rivers drain water from the massive Asian continent into the <a href="http://identifyfish.blogspot.com/2010/10/pacific-barracuda-sphyraena-argentea.html" target="_blank">Pacific</a>, Indian, and Arctic oceans. In China, the Yangtze (Chang Jiang), Yellow (Huang He) and Pearl Rivers carry flowing waters (runoff) from the northern slope of the Himalayan Mountains and western China to the East China Sea. <br />
Hundreds of millions of Chinese people depend on these rivers for their electricity, food, and livelihoods. Water moving south from the Himalayas flows into the rivers of India and South Asia, including the Ganges-Bramaputra system and the Mekong River. The Ganges River of northern India is sacred in the <a href="http://earlyworldhistory.blogspot.com/2012/03/hindu-philosophy.html" target="_blank">Hindu</a> religion. <br />
Hindus travel to its banks to meditate and wash away their sins. Upon death, cremated remains are placed into the Ganges in hopes of improving the deceased’s fortunes in the afterlife. The Ob, Ikysh, Amur and Lena Rivers run across the northern forests and wind-swept tundra (treeless arctic plains) of Siberia (the Asian portion of Russia) into the icy <a href="http://watersome.blogspot.com/2012/09/arctic-and-subarctic-regions.html" target="_blank">Arctic</a> Ocean. <br />
In the Middle East, rivers play an important role in the history and mythology of western civilization. The ancient civilizations of Sumeria and Mesopotamia arose in the “fertile crescent” between the Tigris and Euphrates Rivers (Shat-al-Arab) in what is today Iraq. Along with the Jordan River, they play major roles in Jewish, Christian, and Islamic history.</li>
<li>Australia: The island continent of Australia has only a few major rivers, and its central desert, the outback, is extremely dry. The Murray River and its major tributary (major branch), the Darling, make up Australia’s largest river system. The Murray drains water from the southeastern states of Victoria, New South Wales and southern Queensland and its floodplains are Australia’s most productive farmlands.</li>
<li>Europe: Rivers are intertwined in the history, culture, and geography of Europe. The capital cities of Europe are synonymous with their rivers (London and Thames, Paris and Seine, Vienna, Budapest and Danube). By their very names, the Rhone (France), Rhine (Germany), Volga (Russia), Oder and Elbe (Germany, Poland, Czech Republic), Po and Tiber (Italy), and Ebro (Spain) conjure images of great art and fine wine, desperate battles and bloody conquests, grand castles and ancient hamlets.</li>
<li>North America: The Mississippi and its major tributaries, the Missouri, Ohio, and Arkansas Rivers, collect water from a huge drainage basin that spans the central plains of North America between the Rocky Mountains and the Appalachians. <br />
Canada’s Mackenzie and Churchill Rivers empty into the Arctic Ocean, and the St. Lawrence River empties the Great Lakes into the <a href="http://identifyfish.blogspot.com/2010/10/atlantic-bonito-sarda-sarda.html" target="_blank">Atlantic</a> Ocean. The mighty Yukon River of northern Canada and Alaska carried prospectors to mines and mills during the Alaskan gold rush (1898–99). <br />
Many of the great ports of the Atlantic seaboard and Gulf of Mexico lie near river mouths (the end of a river where the river empties into a larger body of water): New York (Hudson), Philadelphia and Washington, D.C. (Potomac, Susquahana), Norfolk (Delaware), New Orleans (Mississippi), and Houston (Brazos). Rivers, including the Mississippi, Missouri, Colorado, Rio Grande, and Columbia, played central roles in European exploration and settlement of the American West. <br />
Today, the rivers that carried explorers Meriwether Lewis, William Clark, John Wesley Powell, and other legendary frontiersmen across the continent are used for <a href="http://watersome.blogspot.com/2011/11/agricultural-water-use.html" target="_blank">agricultural</a> irrigation, drinking water, recreation, and power generation. Their water is a valuable and heavily-sought resource.<br />
</li>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.pt/2016/07/placebo-effect.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img border="0" src="https://2.bp.blogspot.com/-5LwgTSdjZlc/WLLHpxg6GRI/AAAAAAAAdtk/VVcr06-FUpcS6hHZzhgXgSE5Em6XkAu9gCLcB/s1600/Amazon.jpg" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Amazon river, aerial view</td></tr>
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<li>South America: The Amazon is the largest river in the world. It flows from the Andes Mountains of <a href="http://epicworldhistory.blogspot.com/2012/07/cajamarca-peru.html" target="_blank">Peru</a>, across the Brazil and empties into Atlantic Ocean on the northeast coast of Brazil. <br />
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The Amazon has more than 1,100 tributaries, 17 of which are longer than 1,000 miles (1,609 kilometers) long. The main river runs from west to east just a few degrees south of the equator, and its massive watershed lies entirely within the warm, wet tropical zone.The central Amazon contains Earth’s lushest, wettest, most biologically diverse rainforest. The Orinoco (Venezuela), Sao Francisco (Brazil), Parana (Argentina, Paraguay) and Uruguay (Uruguay, Brazil) rivers are other major waterways of South America.</li>
</ul>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://historyworldsome.blogspot.com/2013/10/victor-emmanuel-ii.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Rivers" border="0" src="https://1.bp.blogspot.com/-3Fsg89aadpo/VHcMsmP2vxI/AAAAAAAABt0/xFYh3DD0B7M/s1600/rivers.jpg" title="Rivers" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Rivers</td></tr>
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<br />Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.comtag:blogger.com,1999:blog-7826461145739184603.post-56204870367449927052012-09-28T23:37:00.001+07:002017-05-03T19:41:07.642+07:00Stream Systems<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://abouthealthsome.blogspot.com/2016/05/sesame-oil.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="Stream passing through the valley, Tash Rabat, Kyrgyzstan" border="0" src="https://3.bp.blogspot.com/-8YVYQAYzCtk/WQnOKWqZ6cI/AAAAAAAAgHc/BNXbsuOB-ZIuY_ysnlNdED2Y4CS1_ZEuACLcB/s1600/stream-valley.jpg" title="Stream passing through the valley, Tash Rabat, Kyrgyzstan" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Stream passing through the valley, Tash Rabat, Kyrgyzstan</td></tr>
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Streams are any size body of moving surface fresh water driven towards sea level by gravity (force of attraction between two masses). Water scientists refer to all bodies of flowing surface water as streams regardless of size, yet in <a href="https://www.amazon.com/gp/product/1624426077/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=1624426077&linkId=03cf311c3aa126b9d58ff6372af304e9" rel="nofollow" target="_blank">common language</a>, streams are considered smaller than rivers. <br />
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Stream systems are networks that collect fresh water runoff from the land and carry it to the <a href="http://be-eco-friendly.blogspot.com/2010/10/ocean-dumping.html" target="_blank">ocean</a>. Together, tree-shaped systems of small branch streams drain vast areas of the continents into large rivers. <br />
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Stream systems of all sizes erode (wear down) sediment (particles of gravel, sand, and silt) along their courses and carve <a href="https://www.amazon.com/gp/product/B008GXJR9S/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B008GXJR9S&linkId=0425c80f14546cdf4c80c7b6c0921161" rel="nofollow" target="_blank">complex patterns</a> into the landscape. They wear down slowrising mountains and fill valleys and lowlands (low and level lands) with layers of <a href="http://watersome.blogspot.com/2011/11/sediment-contamination.html" target="_blank">sediment</a>. Stream systems change character along their courses. <br />
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<a name='more'></a><table align="center" border="0"><tbody>
<tr> <td align="center"><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/gp/product/B01ICA1K2Q/ref=as_li_ss_il?ie=UTF8&linkCode=li3&tag=waterabout-20&linkId=326db370efaa60b814226d102ce3fc6e" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=B01ICA1K2Q&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=B01ICA1K2Q" style="border: none !important; margin: 0px !important;" width="1" /></span><span style="padding-left: 7px; padding-right: 7px;"><a href="https://www.amazon.com/Stream-Ecology-Structure-Function-Running/dp/140205582X/ref=as_li_ss_il?_encoding=UTF8&pd_rd_i=140205582X&pd_rd_r=7NF2ZBRQ54M1PM0173ZA&pd_rd_w=uDmcm&pd_rd_wg=vCd1x&psc=1&refRID=7NF2ZBRQ54M1PM0173ZA&linkCode=li3&tag=waterabout-20&linkId=17e4986f5b3629cae25b9df3ec91ea0c" target="_blank"><img border="0" src="//ws-na.amazon-adsystem.com/widgets/q?_encoding=UTF8&ASIN=140205582X&Format=_SL250_&ID=AsinImage&MarketPlace=US&ServiceVersion=20070822&WS=1&tag=waterabout-20" /></a><img alt="" border="0" height="1" src="https://ir-na.amazon-adsystem.com/e/ir?t=waterabout-20&l=li3&o=1&a=140205582X" style="border: none !important; margin: 0px !important;" width="1" /></span></td> </tr>
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Steep <a href="http://be-eco-friendly.blogspot.com/2011/03/mountain-pygmy-possum.html" target="_blank">mountain</a> streams feed shallow elevated streams that in turn flow into meandering rivers that snake across broad floodplains (flat, low-lying land near a stream that is covered with water when the stream overflows its banks). Deposits of sediment form at river mouths, the area where fresh river water enters the ocean.<br />
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If a <a href="http://amzn.to/2mrEswD" rel="nofollow" target="_blank">rubber duck</a> was dropped into a mountain stream on Pike’s Peak in Colorado, it might tumble down the mountain-side in whitewater rapids to Cripple Creek. From there, the duck would rush over gravel beds where Colorado miners once panned for gold, and then float serenely across Kansas, Oklahoma, and Arkansas on the <a href="https://www.amazon.com/gp/product/B00XRP2HII/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B00XRP2HII&linkId=45dc138fe95c63ab84f84c3a1b1e77cf" rel="nofollow" target="_blank">Arkansas River</a>. <br />
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It would pause to drift across huge man-made reservoirs, and then plunge through the spillways of dams before entering the swift, muddy waters of the Mississippi River. A few weeks or months later, you might spot the duck heading out to sea amid barges and river boats in New Orleans.<br />
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<b>Watersheds and drainage patterns</b><br />
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The land area that drains water into a stream is called a watershed or a <a href="http://amzn.to/2mrJf1g" rel="nofollow" target="_blank">drainage basin</a>. A basin is a natural depression in the surface of the land. Watersheds can be as small as a hillside that feeds a wet-weather creek, and as large as a drainage system like the Amazon Basin that carries the runoff from most of a continent. <br />
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Large watersheds are composed of many smaller drainage basins. The boundaries between <a href="http://watersome.blogspot.com/2011/11/watersheds.html" target="_blank">watersheds</a>, called drainage divides, are ridge lines or high points where water flows down and away in all directions. <br />
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A divide can be limited, like a ridge between two mountain gullies (deep ditches or channels cut in the earth by running water, usually after a rainstorm), or extensive, like the North American Continental Divide along the spine of the <a href="https://www.amazon.com/gp/product/1551051788/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=1551051788&linkId=c33df0417d9d4deaa13e57439972181d" rel="nofollow" target="_blank">Rocky Mountains</a>. <br />
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Water that falls east of the Continental Divide eventually flows into the Atlantic Ocean, and water that falls west of the Rockies ends up in the <a href="http://identifyfish.blogspot.com/2010/10/pacific-barracuda-sphyraena-argentea.html" target="_blank">Pacific</a> Ocean.<br />
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Streams are arranged within watersheds in networks that feed water into larger and larger streams. Tree-shaped (dendritic) systems composed of small branch tributaries (small streams that flow into larger streams) that join and flow into large trunk streams are the most common type of stream drainage pattern. <br />
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Less common drainage patterns develop where rock layers and geologic features affect the paths of streams. Drainage patterns shaped like cross-hatched garden trellises develop in hilly areas where there are ridges and valleys, and streams flow out from round <a href="http://amzn.to/2mry1ts" rel="nofollow" target="_blank">volcanic mountains</a> in radial patterns like spokes on wheels.<br />
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<b>Valley and channels</b><br />
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Streams cut down into the land surface and create valleys. A stream valley includes the entire area between hills on either side of a stream. The water-filled path of the stream at a specific point in time is called a channel. Over time, channels migrate back and forth and fill stream valleys with thick layers of river sediment. <br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://lifeofplant.blogspot.com/2011/03/phosphorus-cycle.html" imageanchor="1" rel="nofollow" style="margin-left: auto; margin-right: auto;" target="_blank"><img alt="snake across wide sediment filled valleys" border="0" src="https://3.bp.blogspot.com/-l_JEbN0OeaQ/WLLVjfo7wHI/AAAAAAAAduE/fwEth0bWumcI1v6uEIZUGqzBXUUj0sLkwCLcB/s1600/river-valley.jpg" title="snake across wide sediment filled valleys" width="470" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">snake across wide sediment filled valleys</td></tr>
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Some streams, particularly those in steep, mountainous terrain have narrow, <a href="https://www.amazon.com/gp/product/B01CWRQSZE/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B01CWRQSZE&linkId=b87814e336a09f2460ba4e13aeed2bb3" rel="nofollow" target="_blank">V-shaped</a> valleys and channels that fill most of the valley floor. Others, including most streams in gently-sloping basins and coastal lowlands have narrow channels that <b>snake across wide sediment filled valleys</b>. <br />
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For example, the <a href="http://historyworldsome.blogspot.com/2013/11/mississippi-river-and-new-orleans.html" rel="nofollow" target="_blank">Mississippi River</a> has carved a valley more than 100 miles (161 kilometers) wide and filled it with sediment hundreds of feet (meters) thick over thousands of years.<br />
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<b>Channel patterns</b><br />
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Stream channels assume different patterns within their valleys: straight, braided and meandering. While many channels have straight segments between meanders or braids, truly straight channels are quite rare. <br />
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They develop in steep, mountainous areas where geologic forces are slowing lifting up the land surface. Water flowing rapidly downhill from mountains saws straight channels down into solid rock.<br />
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Braided streams have many intertwined channels and islands of loose gravel that constantly shift across gravel-filled valley floors. They are common in streams that receive large pulses of water and course-grained sediment. The sediment-choked streams that carry water from the toes of melting <a href="http://watersome.blogspot.com/2012/09/glaciers.html" rel="nofollow" target="_blank">glaciers</a> are typically braided.<br />
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Streams that bend and curve across gently sloping valleys and coastal plains are called meandering streams. (Individual loops and bends are called meanders.) <br />
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During normal weather conditions, water flows in a narrow channel that snakes across broad plains of soft sediment. During floods, muddy water overflows the banks of the channel and deposits layers of mud and silt on the surrounding floodplains. <br />
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River floodplains are typically <a href="https://www.amazon.com/gp/product/B06W55S32B/ref=as_li_tl?ie=UTF8&tag=waterabout-20&camp=1789&creative=9325&linkCode=as2&creativeASIN=B06W55S32B&linkId=e9e99db0758ba7cff10f790789a7eb89" rel="nofollow" target="_blank">fertile farmlands</a> that have been replenished by flood-waters. The coarser grained sediment settles out of flood waters closer to the channel builds natural levees (walls along the banks of a stream channel) along its banks.<br />
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The path of a meandering channel changes over time. Meanders grow from slight bends into nearly-circular loops. At a river bend, fast-flowing water erodes the outer channel bank and sediment accumulates on the inside of the curve in a deposit called a point bar. <br />
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Eventually, the bends at the neck of the meander grow so close that the water bypasses the loop. This process strands crescent-shaped segments of the former channel and round point bar deposits called oxbows on the floodplain. Oxbow lakes are abandoned meanders that contain water.<br />
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Channel patterns change down the course of a stream system between headwater streams and lowland trunk rivers. They also change over time as streams adjust to changing conditions of water flow, land incline, and amounts of sediment. Stream waters continuously erode and deposit sediment over time, and stream channels constantly shift across valley floors.Cinta Mincehttp://www.blogger.com/profile/11856833664021252231noreply@blogger.com