Eutrophication - humans, body, used, water, process, life, plants, chemical Eutrophication City vs City: Compare cities in the U.S. by population, crime, education and other data. Compare: Go! Photo by: Arvind Balaraman Eutrophication (pronounced you-tro-fi-KAY-shun) is a natural process that occurs in an aging lake or pond as that body of water gradually builds up its concentration of plant nutrients. Cultural or artificial eutrophication occurs when human activity introduces increased amounts of these nutrients, which speed up plant growth and eventually choke the lake of all of its animal life. In nature, eutrophication is a common phenomenon in freshwater ecosystems and is really a part of the normal aging process of many lakes and ponds. Some never experience it because of a lack of warmth and light, but many do. Over time, these bodies of freshwater change in terms of how productive or fertile they are. While this is different for each lake or pond, those that are naturally fed rich nutrients from a stream or river or some other natural source are described as "eutrophic," meaning they are nutrient-rich and therefore abundant in plant and animal life.

Eutrophication is not necessarily harmful or bad, and the word itself is often translated from the Greek as meaning "well nourished" or "good food." However, eutrophication can be speeded up artificially, and then the lake and its inhabitants eventually suffer as the input of nutrients increases far beyond what the natural capacity of the lake should be. Words to Know Algae: Single-celled or multicellular plants or plantlike organisms that contain chlorophyll, thus making their own food by photosynthesis. Algae grow mainly in water. Nitrate: A salt or ester of nitric acid, which is a transparent corrosive liquid composed of nitrogen, hydrogen, and oxygen. Phosphate: A salt or ester of a phosphoric acid, which is any of three acids that are formed when the oxide of phosphorus reacts with water. Too much of a good thing Natural eutrophication is usually a fairly slow and gradual process, occurring over a period of many centuries. It occurs naturally when for some reason, production and consumption within the lake do not cancel each other out and the lake slowly becomes overfertilized. While not rare in nature, it does not happen frequently or quickly.

However, artificial or human-caused eutrophication has become so common that the word eutrophication by itself has come to mean a very harmful increase and acceleration of nutrients. It is as if something receives too much fertilizer or has too much of what is a good thing. Humans increase the rate of eutrophication Human activities almost always result in the creation of waste, and many of these waste products often contain nitrates and phosphates. Nitrates are a compound of nitrogen, and most are produced by bacteria. Phosphates are phosphorous compounds. Both nitrates and phosphates are absorbed by plants and are needed for growth. However, the human use of detergents and chemical fertilizers has greatly increased the amount of nitrates and phosphates that are washed into our lakes and ponds. When this occurs in a sufficient quantity, they act like fertilizer for plants and algae and speed up their rate of growth. Algae are a group of plantlike organisms that live in water and can make their own food through photosynthesis (using sunlight to make food from simple chemicals).

When additional phosphates are added to a body of water, the plants begin to grow explosively and algae takes off or "blooms." In the process, the plants and algae consume greater amounts of oxygen in the water, robbing fish and other species of necessary oxygen. All algae eventually die, and when they do, oxygen is required by bacteria in order for them to decompose or break down the dead algae. A cycle then begins in which more bacteria decompose more dead algae, An eutrophic lake. (Reproduced by permission of The Gale Group .) consuming even more oxygen in the process. The bacteria then release more phosphates back into the water, which feed more algae. As levels of oxygen in the body of water become lower, species such as fish and mollusks literally suffocate to death. Eventually, the lake or pond begins to fill in and starts to be choked with plant growth. As the plants die and turn to sediment that sinks, the lake bottom starts to rise. The waters grow shallower and finally the body of water is filled completely and disappears. This also can happen to wetlands, which are already shallow. Eventually, there are shrubs growing where a body of water used to be.

In the 1960s and 1970s, Lake Erie was the most publicized example of eutrophication. Called a "dead lake," the smallest and shallowest of the five Great Lakes was swamped for decades with nutrients from heavily developed agricultural and urban lands. As a result, plant and algae growth choked out most other species living in the lake, and left the beaches unusable due to the smell of decaying algae that washed up on the shores. New pollution controls for sewage treatment plants and agricultural methods by the United States and Canada led to drastic reductions in the amount of nutrients entering the lake. Forty years later, while still not totally free of pollutants and nutrients, Lake Erie is again a biologically thriving lake. Effect of eutrophication and algal boom Norway . To renew all the water in a lake may take up to a hundred years compared to a few days for the renewal of the water in a river. Consequently, lakes are particularly susceptible to pollution such as artificial eutrophication.

The causes of eutrophication The main causes of eutrophication are natural run-off of nutrients from the soil and the weathering of rocks run-off of inorganic fertiliser (containing nitrates and phosphates) run-off of manure from farms (containing nitrates, phosphates and ammonia) run-off from erosion (following mining, construction work or poor land use) discharge of detergents (containing phosphates) discharge of partially treated or untreated sewage (containing nitrates and phosphates) In most freshwater lakes the limiting nutrient is phosphorus, so an input of phosphorus in the form of phosphate ions (PO43-) results in an increase in biological activity. The effects of eutrophication The main effects of eutrophication are an increase in plant and animal biomass increase in growth of rooted plants, e.g. reeds increase in turbidity (cloudiness) of water increase in rate of sedimentation development of anoxic conditions (low oxygen levels) decrease in species diversity change in dominant biota (e.g. carp replace trout and blue-green algae replace normal algae) and an increase in the frequency of algal blooms. Why Should We Be Concerned?

Although eutrophication is a natural process in the aging of lakes and some estuaries, human activities can greatly accelerate eutrophication by increasing the rate at which nutrients and organic substances enter aquatic ecosystems from their surrounding watersheds. Agricultural runoff, urban runoff, leaking septic systems, sewage discharges, eroded streambanks, and similar sources can increase the flow of nutrients and organic substances into aquatic systems. These substances can overstimulate the growth of algae, creating conditions that interfere with the recreational use of lakes and estuaries, and the health and diversity of indigenous fish, plant, and animal populations. Algal blooms hurt the system in two ways. First, they cloud the water and block sunlight, causing underwater grasses to die. Because these grasses provide food and shelter for aquatic creatures (such as the blue crab and summer flounder), spawning and nursery habitat is destroyed and waterfowl have less to eat when grasses die off. Second, when the algae die and decompose, oxygen is used up. Dissolved oxygen in the water is essential to most organisms living in the water, such as fish and crabs.

Increased eutrophication from nutrient enrichment due to human activities is one of the leading problems facing some estuaries in the mid-Atlantic. Algal blooms Algal blooms are one of the more insidious consequences of eutrophication. In addition to being unsightly and smelly, masses of blue-green algae can literally choke the life out of a lake or pond by depriving it of much needed oxygen. At first glance this may seem like something of a paradox - since blue-green algae undergoes photosynthesis, it should produce more oxygen than it consumes. However, after large concentrations of algae have built up, aerobic processes such as respiration and the decomposition of dead algal cells becomes increasingly significant. Under extreme conditions a eutrophic lake or pond may be left entirely devoid of fish. The cause of algal blooms Algal bloom: the rapid excessive growth of algae, generally caused by high nutrient levels and favourable conditions. Blooms can result in deoxygenation of the water mass when large masses of algae die and decompose, leading to the death of aquatic plants and animals. Algal blooms are not a new phenomenon - Captain Cook recorded an algal bloom during his voyage in 1770!

Algae are a natural component of aquatic environments, and even when they are abundant, it is not necessarily a problem. Often a proliferation of microscopic algae can have beneficial effects on fisheries and aquaculture industries such as oyster or mussel farms by increasing the amount of food available. Macroalgae provide sheltered habitat for juvenile fish. In fact, the local fishery production in the Peel-Harvey estuary almost doubled in the 1970s when weed (macroalgae) growth in the estuary was at its peak, without a similar increase in fishing effort. The effect of algal blooms However, when algal blooms increase in intensity and frequency, the results can cause community concern, health problems, and in some cases can be catastrophic to the environment. The impacts are ecological, social and economic. Algal blooms upset the delicate natural balance of plant and animal ecosystems in a waterway or wetland. They can degrade recreation, conservation and scenic values, and interfere with economic uses such as fisheries and tourism. Weed that washes ashore and forms rotting piles on beaches can cause offensive smells and become a health problem for nearby residents as well as a nuisance to beach users and fishers.

An over-abundance of algae can choke a body of water such as a river, clog irrigation pipes, and block out the light other plants, such as seagrasses, need to produce food. Excessive weed growth can eventually kill seagrass beds. When an algal bloom dies the process of decay can use up all the available oxygen in the water, effectively suffocating other aquatic life. This can kill fish, crabs and other animals, especially those that are attached or sedentary (do not move around). Some species of algae produce toxins. Furthermore, algae are a natural and critical part of our Chesapeake Coastal Bays ecosystems. Algae, like land plants, capture the sun嚙踝蕭s energy and support the food web that leads to fish and shellfish. They occur in a size range from tiny microscopic cells floating in the water column (phytoplankton) to large mats of visible 嚙踝蕭macroalgae嚙踝蕭 that grow on bottom sediments. Algae may become harmful if they occur in an unnaturally high abundance or if they produce a toxin.

A high abundance of algae can block sunlight to underwater bay grasses , consume oxygen in the water leading to fish kills, produce surface scum and odors, and interfere with the feeding of shellfish and other organisms that filter water to obtain their food. Some algal species can also produce chemicals that are toxic to humans and aquatic life. Fortunately, of the more than 700 species of algae in Chesapeake Bay , less than 2% of them are believed to have the ability to produce toxic substances. The deterioration of water quality and microbial hazards There are several substances because of unsuitable treatment that cause the deterioration of water. They are as fallows: Oxygen-demanding wastes Most sewage contain organic materials and waste which are oxygen demanding. The natural system can undergo self-purification processes in which the organic materials and waste are broken down by bacterial and other biological activities naturally. During the process, oxygen is consumed. Later, oxygen can be 'refilled' gradually through a number of re-oxygenation processes. However, natural systems have a limited capability to accommodate self-purification. If the oxygen required for biodegradation was greater than the oxygen present in water, oxygen depletion will occur. The activities of organisms will slow down or stop.

Such situation usually happens due to high anthropogenic input of organic materials (like domestic and industrial sewage discharge) into water bodies. Disease-causing agents There are a lot of disease-causing micro-organisms entering the aquatic system by means of contamination from human and animal waste. Human can be affected through different water contact activities, like swimming, water drinking, etc. Diseases like cholera and typhoid may spread. These disease-causing micro-organisms may spread to water only sporadically. And once there, they do not survive long. Thus, it is difficult to test their existence in water. Usually, we use fecal coliform as indicator species, such as Eschericia coli, to identify the problem of water contamination by disease-causing micro-organisms. Thermal pollution It would be cost-effective for industrial and commercial sectors to use water as agent for cooling. However, the discharge of such cooling water may artificially heat up the aquatic environment. Many aquatic organisms can only live within a narrow range of temperature. Different species live in different temperature ranges. Apart from killing them, artificial heating of water can increase the physiological stresses to some species and interfere the natural life processes such as growth rates, respiration, reproduction, and distribution.

Some species can survive in the new environment will become dominant in the ecosystem while previous dominant species become less dominant or even excluded. Heating up water can also reduce the dissolved oxygen which may directly kill aquatic species through asphyxiation. Sediments In water, toxic chemicals can become attached, or absorbed, to sediment particles and then transported to and deposited in other areas. These pollutants can affect the organisms which live there and can build up toxin in organisms that feed on them, and so be passed along the food chain, causing problems all along the way. Sediments can also reduce the sunlight penetrating into water and thus the affecting photosynthesis for aquatic plants. Plant nutrients Plant nutrients, like nitrate and phosphate fertilizers are important to plant growth. However, too much fertilization encourages the overabundance of plant life. Eutrophication is the process by which the nutrient content in water is increased suddenly. It is a natural phenomenon until human accelerates it. The prime contaminants are nitrates and phosphates, they overstimulate the growth of algae, causing unsightly scum and unpleasant odors, and depleting the DO of water that is vital to other aquatic life.

Moreover, the algae cloud the water and block sunlight, causing underwater plants to die. Because these plants provide food and shelter for aquatic creatures (such as the blue crab and summer flounder), spawning and nursery habitat is destroyed and waterfowl have less to eat when plants die off. In urban area, plant nutrients (nitrates and phosphates) enter the natural environment through anthropogenic sources, like sewage treatment effluents. In rural area, they enter the environment through applying fertilizer. Petroleum hydrocarbons Petroleum hydrocarbons in water can cause smothering in water, and also result in adverse health impacts on living organisms, loss of habitat, etc. Human activities introduce a great amount of petroleum hydrocarbons into water, including daily sewage, leaching, oil spills, underground tank leaks, etc. Inorganic chemicals and minerals Inorganic chemicals and minerals pollutants, such as acids and heavy metals, are directly or indirectly discharged from industrial and mining processes into sediments and water bodies. Acid rain and runoff not only threaten aquatic life directly through the effects of lowering pH, but also indirectly leaching, which may increase the heavy metal burden on receiving water bodies.

Synthetic organic compounds There are huge amount of synthetic organic compounds worldwide, including plastics, solvents, detergents, pesticides, PCBs (Polychlorinated Biphenyls), pharmaceuticals, paints, etc. They are accidentally or intentionally discharged into the aquatic system. Some of the pure products, by-products, and waste products have a powerful and acute effect (quick impacts) or a long-term, chronic effect on the aquatic ecosystems. Since they are synthetic, these compounds may be resistant to biological breakdown and they may persist and accumulate in the environment or organisms. Causes of Water Pollution in Hong Kong There are three basic causes of water pollution in Hong Kong, including: i) Multiplicity of Sources There are many sources of water pollution, including anthropogenic (household, commercial, industrial, farming, etc.) and natural sources. Moreover, these sources are close to one another and in huge amount. Dredging and sea dumping activity can also lead to water pollution.

ii) Lack of Infrastructure Eutrophication - Definition, Glossary, Details - Oilgae Download free sample report of Algae Fuels Report Know More Eutrophication - Definition, Glossary, Details - Oilgae Eutrophication - Eutrophication is a process whereby water bodies, such as lakes, estuaries, or slow-moving streams receive excess nutrients that stimulate excessive plant growth (algae, periphyton attached algae, and nuisance plants weeds). This enhanced plant growth, often called an algal bloom, reduces dissolved oxygen in the water when dead plant material decomposes and can cause other organisms to die. Nutrients can come from many sources, such as fertilizers applied to agricultural fields, golf courses, and suburban lawns; deposition of nitrogen from the atmosphere; erosion of soil containing nutrients; and sewage treatment plant discharges. Eutrophication - Natural eutrophication is the process by which lakes gradually age and become more productive. It normally takes thousands of years to progress. However, humans, through their various cultural activities, have greatly accelerated this process in thousands of lakes around the globe. Cultural or anthropogenic eutrophication is water pollution caused by excessive plant nutrients.

Links Eutrophication - Eutrophication (pronounced you-tro-fi-KAY-shun) is a natural process that occurs in an aging lake or pond as that body of water gradually builds up its concentration of plant nutrients. Cultural or artificial eutrophication occurs when human activity introduces increased amounts of these nutrients, which speed up plant growth and eventually choke the lake of all of its animal life. Eutrophication Experiments - Eutrophication is derived from two Latin words meaning good and food. In studies of freshwater ecosystems, the term is used to refer to the process by which lakes, ponds, and streams become enriched with inorganic plant nutrients, especially phosphorus and nitrogen. This process happens naturally over a long period of time as dead organic matter accumulates, and is one step in the normal succession of the freshwater ecosystem. Eutrophication: Causes, Consequences, and Controls in Aquatic Ecosystems | Learn Science at Scitable Eutrophication: Causes, Consequences, and Controls in Aquatic Ecosystems By: Michael F. Chislock (Department of Fisheries and Allied Aquacultures, Auburn University), Enrique Doster (Department of Animal Sciences, Auburn University), Rachel A.

Zitomer (Department of Biological Sciences, Humboldt University) & Alan E. Wilson (Department of Fisheries and Allied Aquacultures, Auburn University) © 2013 Nature Education Citation: Chislock, M. F., Doster, E., Zitomer, R. A. & Wilson, A. E. (2013) Eutrophication: Causes, Consequences, and Controls in Aquatic Ecosystems. Nature Education Knowledge 4(4):10 Eutrophication is a leading cause of impairment of many freshwater and coastal marine ecosystems in the world. Why should we worry about eutrophication and how is this problem managed? Introduction Eutrophication is characterized by excessive plant and algal growth due to the increased availability of one or more limiting growth factors needed for photosynthesis (Schindler 2006), such as sunlight, carbon dioxide, and nutrient fertilizers. Eutrophication occurs naturally over centuries as lakes age and are filled in with sediments (Carpenter 1981).

However, human activities have accelerated the rate and extent of eutrophication through both point-source discharges and non-point loadings of limiting nutrients, such as nitrogen and phosphorus, into aquatic ecosystems (i.e., cultural eutrophication), with dramatic consequences for drinking water sources, fisheries, and recreational water bodies (Carpenter et al. 1998). For example, aquaculture scientists and pond managers often intentionally eutrophy water bodies by adding fertilizers to enhance primary productivity and increase the density and biomass of recreationally and economically important fishes (Figure 1) via bottom-up effects on higher trophic levels (Boyd & Tucker 1998). However, during the 1960s and 1970s, scientists linked algal blooms to nutrient enrichment resulting from anthropogenic activities such as agriculture, industry, and sewage disposal (Schindler 1974). The known consequences of cultural eutrophication include blooms of blue-green algae (i.e., cyanobacteria, Figure 2), tainted drinking water supplies, degradation of recreational opportunities, and hypoxia. The estimated cost of damage mediated by eutrophication in the U.S.

alone is approximately $2.2 billion annually (Dodds et al. 2009). Figure 1 Aquaculture ponds, such as these channel catfish production ponds, typically contain high concentrations of nutrients, such as nitrogen and phosphorus, due to regular feeding of the fish. Consequently, these ponds are also plagued by recurring cyanobacterial blooms and hypoxia. © 2013 Nature Education Photos by Mark Peterman and Michael Chislock. All rights reserved. Figure 2 Sampling Lago de Pátzcuaro during a cyanobacterial bloom with Ilyana Berry, Dr. John Berry, and Dr. Fernando Bernal-Brooks. © 2013 Nature Education Photo by Alan Wilson. All rights reserved. Consequences The most conspicuous effect of cultural eutrophication is the creation of dense blooms of noxious, foul-smelling phytoplankton that reduce water clarity and harm water quality (Figure 2). Algal blooms limit light penetration, reducing growth and causing die-offs of plants in littoral zones while also lowering the success of predators that need light to pursue and catch prey (Lehtiniemi et al. 2005).

Furthermore, high rates of photosynthesis associated with eutrophication can deplete dissolved inorganic carbon and raise pH to extreme levels during the day. Elevated pH can in turn ‘blind' organisms that rely on perception of dissolved chemical cues for their survival by impairing their chemosensory abilities (Figure 3) (Turner & Chislock 2010). When these dense algal blooms eventually die, microbial decomposition severely depletes dissolved oxygen, creating a hypoxic or anoxic ‘dead zone' lacking sufficient oxygen to support most organisms. Dead zones are found in many freshwater lakes including the Laurentian Great Lakes (e.g., central basin of Lake Erie; Arend et al. 2011) during the summer. Furthermore, such hypoxic events are particularly common in marine coastal environments surrounding large, nutrient-rich rivers (e.g., Mississippi River and the Gulf of Mexico; Susquehanna River and the Chesapeake Bay) and have been shown to affect more than 245,000 square kilometers in over 400 near-shore systems (Diaz & Rosenberg 2008).

Hypoxia and anoxia as a result of eutrophication continue to threaten lucrative commercial and recreational fisheries worldwide. Figure 3 Helisoma trivolvis (left) and Physa acuta (right) are two of the most common freshwater snails in North America. Both species use chemical cues to detect predators such as molluscivorous fish and typically respond by hiding under rocks and logs or in shallow water. © 2013 Nature Education Photo by Andy Turner. All rights reserved. Some algal blooms pose an additional threat because they produce noxious toxins (e.g., microcystin and anatoxin-a; Chorus and Bartram 1999). Over the past century, harmful algal blooms (HABs) have been linked with (1) degradation of water quality (Francis 1878), (2) destruction of economically important fisheries (Burkholder et al. 1992), and (3) public health risks (Morris 1999). Within freshwater ecosystems, cyanobacteria are the most important phytoplankton associated with HABs (Paerl 1988).

Toxigenic cyanobacteria, including Anabaena, Cylindrospermopsis, Microcystis, and Oscillatoria (Planktothrix), tend to dominate nutrient-rich, freshwater systems due to their superior competitive abilities under high nutrient concentrations, low nitrogen-to-phosphorus ratios, low light levels, reduced mixing, and high temperatures (Downing et al. 2001; Paerl & Huisman 2009; Paerl and Paul 2012). Poisonings of domestic animals, wildlife (Figure 4), and even humans by blooms of toxic cyanobacteria have been documented throughout the world and date back to Francis' (1878) first observation of dead livestock associated with a bloom of cyanobacteria. Furthermore, cyanobacteria are responsible for several off-flavor compounds (e.g., methylisoborneal and geosmin) found in municipal drinking water systems as well as in aquaculture-rased fishes, resulting in large financial losses for state and regional economies (Crews & Chappell 2007).

In addition to posing significant public health risks, cyanobacteria have been shown to be poor quality food for most zooplankton grazers in laboratory studies (Wilson et al. 2006; Tillmanns et al. 2008), thus reducing the efficiency of energy transfer in aquatic food webs and potentially preventing zooplankton from controlling algal blooms. Figure 4 A dead African buffalo (Syncerus caffer) found in a reservoir with a dense bloom of the toxic cyanobacterium Microcystis at the Loskop Dam Nature Reserve in South Africa. © 2013 Nature Education Photo by Jannie Coetzee. All rights reserved. Eutrophication is also associated with major changes in aquatic community structure. During cyanobacterial blooms, small-bodied zooplankton tend to dominate plankton communities, and past observational studies have attributed this pattern to anti-herbivore traits of cyanobacteria (e.g., toxicity, morphology, and poor food quality) (Porter 1977). However, the biomass of planktivorous fish is often positively related to nutrient levels and ecosystem productivity.

Piscivorous fishes (e.g., bass, pike) tend to dominate the fish community of nutrient-poor, oligotrophic lakes, while planktivorous fishes (e.g., shad, bream) become increasingly dominant with nutrient enrichment (Jeppesen et al. 1997). Thus, an alternative explanation for the lack of zooplankton control of cyanobacterial blooms could include consumption of zooplankton by planktivores. Controls Given the widespread extent of water quality degradation associated with nutrient enrichment, eutrophication has and continues to pose a serious threat to potable drinking water sources, fisheries, and recreational water bodies. Although many municipalities have passed legislation to regulate point-source loading of nutrients, eutrophication and cyanobacterial blooms are still prevalent in surface waters around the world (Smith & Schindler 2009). Predicted climate change and human population growth has the potential to further degrade water quality and quantity, and there is an immediate need by water resource managers to understand how to minimize the intensity and frequency of algal and cyanobacterial blooms (Paerl & Paul 2012).

Water resource managers routinely employ a variety of strategies to minimize the effects of cultural eutrophication, including (1) diversion of excess nutrients (Edmondson 1970), (2) altering nutrient ratios (Downing et al. 2001), (3) physical mixing (Huisman et al. 2004), (4) shading water bodies with opaque liners or water-based stains, and (5) application of potent algaecides and herbicides (Boyd & Tucker 1998). In general, these strategies have proven to be ineffective, costly, and/or impractical, especially for large, complex ecosystems (but see Edmondson 1970). Water quality can often be improved by reducing nitrogen and/or phosphorus inputs into aquatic systems, and there are several well-known examples where bottom-up control of nutrients has greatly improved water clarity. However, nutrient reduction can be difficult (and expensive) to control, especially in agricultural areas where the algal nutrients come from nonpoint sources. Furthermore, in lakes where external loading of nutrients has been reduced, internal loading of nutrients from sediments may prevent improvements in water quality (Søndergaard et al. 2003).

The use of algaecides, such as copper sulfate, is also effective at reducing HABs temporally (Boyd & Tucker 1998). However, algaecides are expensive to apply, do not control the primary cause of the problem (i.e., abundant resources for primary producers) and pose risks to humans, livestock, and wildlife, in addition to harming a variety of non-target aquatic organisms. Another alternative for improving water quality in nutrient-rich lakes has been biomanipulation - the alteration of a food web to restore ecosystem health (Shapiro et al. 1975). The basic premise is that secondary consumers (planktivorous fishes) are removed either through the addition of tertiary consumers (piscivorous fishes) or harvesting, which allows for the dominance of large-bodied, generalist grazers (e.g., Daphnia) to control phytoplankton (Figure 5).

When planktivorous fishes are abundant and there is no predation refuge (e.g., oxygenated hypolimnion) for large-bodied zooplankton, less efficient small-bodied zooplankton grazers (e.g., rotifers and herbivorous copepods) typically dominate zooplankton communities, thus allowing for the overgrowth of phytoplankton (i.e., algal bloom). Many past studies have shown strong correlations between the size structure of zooplankton communities and phytoplankton abundance. These data support the notion that predatory top-down forces can have important implications for aquatic communities and ecosystems. With that said, fish-centric biomanipulation effects on water quality are typically short-lived (i.e., weeks to months), most obvious in small, easily-managed systems (i.e., ponds), and impacted by resource availability, namely phosphorus and nitrogen (Benndorf 1990; Carpenter et al. 1995). Figure 5 Daphnia are generalist herbivores that play a powerful role in the structure and function of lake ecosystems and can have large effects on phytoplankton abundance, water clarity, and water quality when abundant.

© 2013 Nature Education Photo by Alan Wilson. All rights reserved. Conclusions Despite dramatic improvements in water quality as a result of large-scale efforts to reduce nutrient enrichment (e.g., Clean Water and Safe Drinking Water Acts in the 1970s), cultural eutrophication and concomitant HABs continue to be the leading cause of water pollution for many freshwater and coastal marine ecosystems and are a rapidly growing problem in the developing world (Smith & Schindler 2009). Given that the demand for freshwater resources is expected to increase dramatically, protecting diminishing water resources has become one of the most pressing environmental issues and will likely become more complicated as climate change, species invasions, and pollution further degrade water quality and quantity (Schindler 2006). Control and management of cultural eutrophication is a complex issue and will require the collective efforts of scientists, policy makers, and citizens to reduce nutrient inputs, to develop effective, long-term biomanipulation techniques, and to eventually restore aquatic communities. Glossary IETC homepage Lakes and Reservoirs vol.

3 Water Quality: The Impact of Eutrophication Where Nutrients Come From and How They Cause Entrophication Where Nutrients Come From What are the sources of nutrients causing eutrophication of lakes and reservoirs? There are many sources. All activities in the entire drainage area of a lake or reservoir are reflected directly or indirectly in the water quality of these water bodies. A lake or reservoir may, however, be naturally eutrophied when situated in a fertile area with naturally nutrient enriched soils. In many lakes and reservoirs wastewater is the main source since untreated wastewater or wastewater treated only by a conventional mechanical- biological methods still contains nitrogen (25-40 mg per liter) and phosphorus (6-10 mg per liter). Both nitrogen and phosphorus can be removed by well-known technology - phosphorus by addition of a chemical that precipitates phosphate though a chemical reaction, and nitrogen usually by biological means through micro- organism activity. Nitrogen costs more money and also, technically speaking, is more difficult to remove than phosphorus. Photo 20: General view of a wetland. Drainage water from agricultural land also contains phosphorus and nitrogen. It usually has much more nitrogen because phosphorus is usually bound to soil components.

Extensive use of fertilizers results in significant concentrations of nutrients particularly nitrogen, in agricultural runoff. If eroded soil reaches the lake, both phosphorus and the nitrogen in the soil contribute to eutrophication. Erosion is often caused by deforestation which also results from unwise planning and management of the resource. Wetlands are increasingly used to solve the problem of diffuse pollution from agriculture which cause eutrophication (Photo 20). Nitrate is converted in wetlands to free nitrogen and released to the air. This is not harmful, as free nitrogen compromises about 4/ 5ths of the atmosphere. Phosphorus is adsorbed by wetland soils and, like nitrogen, is taken up by the plants. Both nitrogen and phosphorus may therefore be removed by wetlands. In addition, it is often also necessary to control fertilizer usage in agricultural practices as the majority may end up in the drainage area, if the diffuse pollution from nutrients is to be reduced sufficiently to improve water quality. Photo 21: Aerial view of fish pens in Laguna de Bay, Philippines. Rain water contains phosphorus and nitrogen from air pollution.

As nitrogen is more mobile in the atmosphere than phosphorus, it is usually over 20 times more concentrated than phosphorus. Nitrogen can only be reduced in rain water by extensive controls of the air pollution in the entire region. One can safely say that the main sources of pollution in the atmosphere are from industries and automobile exhaust without proper filtering systems. When lakes are used for aquaculture, excess fish food pollutes the water as complete use of the food cannot be achieved (Photo 21). Nitrogen and phosphorus present in the excess food is dissolved or suspended in the water. The use of lakes for aquaculture therefore needs careful environmental planning and management practices by the owners and workers. The sediment of a lake -its muddy bottom layer -contains relatively high concentrations of nitrogen and phosphorus. These can be released to water, particularly under conditions of low oxygen concentrations. The nutrients in the sediment come from the past settling of algae and dead organic matter. The nutrients released from sediments are referred to as the lakeï¿½s internal loading . Figure 5 sketches the sources of nutrients: externally from wastewater, agricultural drainage water, erosion and rain, and internally from activities in the lake itself, e.g. aquaculture and sediment release.

It is possible but very expensive to remove the upper nutrient-rich layer of sediment. Covering sediments with clay to seal them and thereby reduce internal loading has also been tried. Even when nutrients are removed in large amounts from wastewater, agricultural drainage water and rain, it often takes much time before nutrient concentrations fall in the upper sediment layer because they are still present in the water environment. Early reduction or elimination of nutrient sources is therefore very important. Fig. 5: Major sources of nutrients in lakes. Lakes and reservoirs can be classified according to the extent of their eutrophication (or nutrients enrichment) into four main classes: oligotrophic, mesotrophic, eutrophic and hypereutrophic (Table 3). This classification results from extensive examination of eutrophication in countries within the Organization for Economic Cooperation and Development (OECD) in the 1970s and early 1980s. It is based on concentrations of phosphorus, nitrogen and chlorophyll a (the green plant pigment needed in photosynthesis). Chlorophyll a roughly indicates the concentration of plant biomass (on average 1% of algae biomass is chlorophyll a).

Factors that limit Eutrophication Table 4 shows the average composition of freshwater plants on a wet basis (when they are not dried): the plants require all listed components in the approximate percentages indicated. Generally, nitrogen (0.7%) and/or phosphorus (0.09%) are usually the first components depleted when plants form following photosynthesis. These two nutrients are less abundant in water than other elements needed, relative to their composition in plants. About eight times more nitrogen is required than phosphorus. Phosphorus thus limits eutrophication if nitrogen is more than eight times as abundant as phosphorus, while nitrogen limits eutrophication if its concentration is less than eight times as abundant as phosphorus. Photo 22: Growth of blue-green algae on the shore of a lake. Untreated wastewater and wastewater treated by mechanical-biological methods contain about 32mg/L nitrogen and about 8 mg/L phosphorus on average. In a lake heavily loaded with wastewater, eutrophication is limited by nitrogen, as the nitrogen concentration in the discharged wastewater is only four times the phosphorus concentration. Such lakes often display extensive blooms of blue-green algae as unsightly surface scum (Photo 22).

Some species of blue-green algae use nitrogen directly from the air and grow, although dissolved nitrogen is limiting. Lakes that receive natural tributaries and drainage water from agriculture, however, have high nitrogen concentrations and are therefore usually limited by phosphorus. The central question is not to determine which nutrient is limiting but to determine which nutrient can most easily be made limiting. As phosphorus is more easily and less expensively removed from wastewater than nitrogen, in many cases (but not all) the best environmental management strategy for lakes and reservoirs is to remove as much phosphorus as possible from wastewater. Eutrophication | Chemistry@TutorVista.com Eutrophication Eutrophication is the condition in which the growth of water plants takes place in excess amount. This is the condition in which the nutrients present in the waste materials which are thrown in water are absorbed by the water plants due to which their growth becomes very high. This is also known as the over fertilization of plants in the water. The local ecosystem is also greatly affected by the growth of plants. These plants which grows in excess are known as phytoplanktons. The excessive growth of plants in the water causes so many problems for the animals present in the water.

The oxygen dissolved in the water is consumed by the plants which causes the death of animals present in the water. Eutrophication can be of two types. Man made When the waste materials like sewage effluents are thrown in the water than it contains some nutrients which causes this problem. Also the fertilizers used in the agriculture comes in the water,which is very helpful for the growth of the phytoplankton's. Natural This is the process in which the nutrients are added to the water naturally, by rain water or any other resources. Back to Top Major sources of excess nutrients which are responsible for eutrophication are agricultural fertilizers, livestock wastes and domestic sewage. Agricultural fertilizers provide inorganic nutrients like nitrates and phosphates which play an important role in this process. However sewage and other wastes provide both inorganic and organic nutrients. There are two major causes for eutrophication in aquatic systems that are excess of nitrogen and phosphate in water. Generally these two nutrients added in aquatic system by human activities. Nitrogenous compounds The nitrogen level in atmosphere is continually increases because of automobiles which further increase soil nitrogen availability. As the plants have high nitrogen requirements for stimulate plant growth, many nitrogen based fertilizer are used.

As nitrogen exists in gaseous form only, hence it is available in form of different nitrogenous compounds like nitrates. However the excess addition of nitrogenous compound leaches in the water system. Generally nitrate compounds are water soluble and easily leach into groundwater and end up in surface runoff. At the same time, polluted water may enter in lake and river and contributed to eutrophication. The ingested nitrate compounds in living organism binds with hemoglobin and reducing its oxygen carrying capacity in aquatic life particularly in amphibians. However, the leaching of phosphorus is a very slow process, therefore it may be limiting in marine environments, compare to nitrogenous compounds. Phosphorus compounds Phosphorus compounds like phosphates are not water soluble but they do adhere to the soil particles and accumulate in soil. The main culprit of eutrophication in lake is phosphorus compounds which subjected to point source pollution from sewage. A study proves that humankind has increased the rate of phosphorus cycling on Earth by four times, due to agricultural fertilizer production and application. Study between 1950 and 1995, around 600,000,000 tonnes of phosphorus were applied to Earth's surface.

Effects of Eutrophication Back to Top The algal bloom mainly effect the aquatic life as the cycle of algae is quite opposite to animals and other photosynthetic organism. Algae release oxygen during the day and absorb more carbon dioxide, while animal and other non-photosynthetic organisms so just opposite to that. At night, algae usually react in an opposite manner and act as dead organic matter adding BOD(biological oxygen demand) load. The main effects of eutrophication can be summarized as follows. Due to the organisms high concentration in a eutrophic system, the competition within available resources along with predator-prey ratio increases. Occasional high chemical and physical stress results in the struggle for survival leading to the decrease in diversity of organisms. This also brings changes in eutrophic and dominant biota. The biomass of plant and animal increases with turbidity. 1. Blooming of Algae and Cyano bacteria The cultural eutrophication may lead to excessive algal bloom in aquatic system and overloaded algae in system. The decomposition of these blooms produce offensive sewage-like odor.

At the end of their growing season, when algae die, they settle at the bottom and release mineral and organic nutrients and serve as the growing bed for the next algal cycle. Hence serve as a form of secondary pollution. Generally the development of blue-green algal (Cyanobacteria) blooms is a common symptoms of lake eutrophication which generated by human activity. 2. Excessive aquatic macrophyte growth In addition to algae and cyanobacteria, the high level of nutrient can stimulate some other forms of primary productions also like aquatic macrophytes. These macrophytes can affect the recreational and industrial activity with the alteration of the structure of the food web. The growth of phytoplankton and other varieties of macroscopic plants in the water bodies leads to aesthetic problem resulting in the reduced value of the water body as a resource of recreation as well as raise turbidity in water. 3. Oxygen depletion in deep water Oxygen is a necessary gas for all living systems except bacteria. Hence eutrophication which increases the organic matter in water, associated with the oxygen depletion.

This problem can preclude aquatic animals from living in deep water regions of lakes devoid of proper level of oxygen resulting in hypoxia and causes a seasonal or nocturnal phenomenon. Overall eeutrophication brings about changes in water chemistry by changing the pH, amount of dissolved gases and other minerals like phosphate, nitrates etc. pH â The quantity of carbon dioxide gas and other mineral, organic and inorganic acids decides the pH of aquatic system. pH below 5 and above 9 i.e. more acidic or more basic are definitely harmful to aquatic animals and limit growth of algal and invertebrate populations. Dissolved O2 -The amount of dissolved oxygen in water depends upon the temperature and pressure of system. Its decreases with high temperature or pressure. As oxygen is a main component for all living organism, the oxygen levels fall below 4-5 mg/l for extended periods of time can lethal for most of the invertebrates. Carbon dioxide (CO2)- Carbon dioxide is largely effects the pH of aquatic system. It is a product of aerobic and anaerobic decomposition of organic matter which further reacts with water to form carbonic acid (H2CO3).

The optimum concentration of CO2 has in water is less than 1 mg/l. While the high concentration shows lethal effect of aquatic system. Phosphates - The high concentration of phosphate stimulate the algal bloom. It is present in low quantities in natural waters around 0.01 mg/l and released during decomposition only. Ammonia (NH3 or NH4+) - It is a main product of decomposition of animal and plant protein and an important plant nutrient. The concentration of ammonia is very less in natural bodies of water and higher level stimulates algal growth which is toxic for aquatic animals. The excessive enrichment of water bodies by nutrients promote the plant growth and decay which leads to drop in water quality and disruption of the natural ecosystem. The algal bloom acts as algal shading and prevents marine plants from receiving enough sunlight to photosynthesize. Due to slow photosynthesis process, the amount of dissolved oxygen decreases. Thus it becomes difficult for many marine animals to survive. Eutrophication leads to reduce the recreational and aesthetic value of water bodies. The effected water can create many health problems due to the presence of various microbes which involve in the decomposition of organic matter.

Related Topics Eutrophication : definition of Eutrophication and synonyms of Eutrophication (English) 10 External links Lakes and rivers Eutrophication can be human-caused or natural. Untreated sewage effluent and agricultural run-off carrying fertilizers are examples of human-caused eutrophication. However, it also occurs naturally in situations where nutrients accumulate (e.g. depositional environments), or where they flow into systems on an ephemeral basis. Eutrophication generally promotes excessive plant growth and decay, favouring simple algae and plankton over other more complicated plants, and causes a severe reduction in water quality. Phosphorus is a necessary nutrient for plants to live, and is the limiting factor for plant growth in many freshwater ecosystems. The addition of phosphorus increases algal growth, but not all phosphates actually feed algae. [2] These algae assimilate the other necessary nutrients needed for plants and animals. When algae die they sink to the bottom where they are decomposed and the nutrients contained in organic matter are converted into inorganic form by bacteria. The decomposition process uses oxygen and deprives the deeper waters of oxygen which can kill fish and other organisms.

Also the necessary nutrients are all at the bottom of the aquatic ecosystem and if they are not brought up closer to the surface, where there is more available light allowing for photosynthesis for aquatic plants, a serious strain is placed on algae populations. Enhanced growth of aquatic vegetation or phytoplankton and algal blooms disrupts normal functioning of the ecosystem, causing a variety of problems such as a lack of oxygen needed for fish and shellfish to survive. The water becomes cloudy, typically coloured a shade of green, yellow, brown, or red. Eutrophication also decreases the value of rivers, lakes, and estuaries for recreation, fishing, hunting, and aesthetic enjoyment. Health problems can occur where eutrophic conditions interfere with drinking water treatment . [3] Eutrophication was recognized as a water pollution problem in European and North American lakes and reservoirs in the mid-20th century. [4] Since then, it has become more widespread. Surveys showed that 54% of lakes in Asia are eutrophic ; in Europe , 53%; in North America , 48%; in South America , 41%; and in Africa , 28%.

[5] Although eutrophication is commonly caused by human activities, it can also be a natural process particularly in lakes. Eutrophy occurs in many lakes in temperate grasslands, for instance. Paleolimnologists now recognise that climate change, geology, and other external influences are critical in regulating the natural productivity of lakes. Some lakes also demonstrate the reverse process ( meiotrophication ), becoming less nutrient rich with time. [6] [7] Eutrophication can also be a natural process in seasonally inundated tropical floodplains. In the Barotse Floodplain of the Zambezi River , the first floodwaters of the rainy season are usually hypoxic because of material such as cattle manure and previous decay of vegetation which grew during the dry season. These so-called "red waters" kill many fish. [8] The process can be made worse by the use of fertilizers in crops such as maize, rice, and sugarcane grown on the floodplain. Human activities can accelerate the rate at which nutrients enter ecosystems . Runoff from agriculture and development, pollution from septic systems and sewers , and other human-related activities increase the flow of both inorganic nutrients and organic substances into ecosystems.

Elevated levels of atmospheric compounds of nitrogen can increase nitrogen availability. Phosphorus is often regarded as the main culprit in cases of eutrophication in lakes subjected to "point source" pollution from sewage pipes. The concentration of algae and the trophic state of lakes correspond well to phosphorus levels in water. Studies conducted in the Experimental Lakes Area in Ontario have shown a relationship between the addition of phosphorus and the rate of eutrophication. Humankind has increased the rate of phosphorus cycling on Earth by four times, mainly due to agricultural fertilizer production and application. Between 1950 and 1995, an estimated 600,000,000 tonnes of phosphorus were applied to Earth's surface, primarily on croplands. [9] Policy changes to control point sources of phosphorus have resulted in rapid control of eutrophication.[ citation needed ] Ocean waters Eutrophication is a common phenomenon in coastal waters. In contrast to freshwater systems, nitrogen is more commonly the key limiting nutrient of marine waters; thus, nitrogen levels have greater importance to understanding eutrophication problems in salt water.

Estuaries tend to be naturally eutrophic because land-derived nutrients are concentrated where run-off enters a confined channel. Upwelling in coastal systems also promotes increased productivity by conveying deep, nutrient-rich waters to the surface, where the nutrients can be assimilated by algae . The World Resources Institute has identified 375 hypoxic coastal zones in the world, concentrated in coastal areas in Western Europe, the Eastern and Southern coasts of the US, and East Asia, particularly Japan. [10] In addition to runoff from land, atmospheric fixed nitrogen can enter the open ocean. A study in 2008 found that this could account for around one third of the ocean’s external (non-recycled) nitrogen supply, and up to 3% of the annual new marine biological production. [11] It has been suggested that accumulating reactive nitrogen in the environment may prove as serious as putting carbon dioxide in the atmosphere. [12] Terrestrial ecosystems Terrestrial ecosystems are subject to similarly adverse impacts from eutrophication. [13] Increased nitrates in soil are frequently undesirable for plants. Many terrestrial plant species are endangered as a result of soil eutrophication, such as the majority of orchid species in Europe.

[14] Meadows, forests, and bogs are characterized by low nutrient content and slowly growing species adapted to those levels, so they can be overgrown by faster growing and more competitive species. In meadows, tall grasses that can take advantage of higher nitrogen levels may change the area so that natural species may be lost. Species-rich fens can be overtaken by reed or reedgrass species. Forest undergrowth affected by run-off from a nearby fertilized field can be turned into a nettle and bramble thicket. Chemical forms of nitrogen are most often of concern with regard to eutrophication, because plants have high nitrogen requirements so that additions of nitrogen compounds will stimulate plant growth. Nitrogen is not readily available in soil because N2, a gaseous form of nitrogen, is very stable and unavailable directly to higher plants. Terrestrial ecosystems rely on microbial nitrogen fixation to convert N2 into other forms such as nitrates . However, there is a limit to how much nitrogen can be utilized. Ecosystems receiving more nitrogen than the plants require are called nitrogen-saturated.

Saturated terrestrial ecosystems then can contribute both inorganic and organic nitrogen to freshwater, coastal, and marine eutrophication, where nitrogen is also typically a limiting nutrient . [15] This is also the case with increased levels of phosphorus. However, because phosphorus is generally much less soluble than nitrogen, it is leached from the soil at a much slower rate than nitrogen. Consequently, phosphorus is much more important as a limiting nutrient in aquatic systems. [16] Ecological effects Eutrophication is apparent as increased turbidity in the northern part of the Caspian Sea , imaged from orbit. Many ecological effects can arise from stimulating primary production , but there are three particularly troubling ecological impacts: decreased biodiversity, changes in species composition and dominance, and toxicity effects. Increased biomass of phytoplankton Increased incidences of fish kills Loss of desirable fish species Reductions in harvestable fish and shellfish Decreases in perceived aesthetic value of the water body Decreased biodiversity When an ecosystem experiences an increase in nutrients, primary producers reap the benefits first. In aquatic ecosystems, species such as algae experience a population increase (called an algal bloom ).

Algal blooms limit the sunlight available to bottom-dwelling organisms and cause wide swings in the amount of dissolved oxygen in the water. Oxygen is required by all aerobically respiring plants and animals and it is replenished in daylight by photosynthesizing plants and algae.As they cannot photosynthesis, the method of plants produces energy, and oxygen. Under eutrophic conditions, dissolved oxygen greatly increases during the day, but is greatly reduced after dark by the respiring algae and by microorganisms that feed on the increasing mass of dead algae. When dissolved oxygen levels decline to hypoxic levels, fish and other marine animals suffocate. As a result, creatures such as fish, shrimp, and especially immobile bottom dwellers die off. [17] In extreme cases, anaerobic conditions ensue, promoting growth of bacteria such as Clostridium botulinum that produces toxins deadly to birds and mammals. Zones where this occurs are known as dead zones . New species invasion Eutrophication may cause competitive release by making abundant a normally limiting nutrient . This process causes shifts in the species composition of ecosystems. For instance, an increase in nitrogen might allow new, competitive species to invade and out-compete original inhabitant species.

This has been shown to occur [18] in New England salt marshes . Toxicity Some algal blooms , otherwise called "nuisance algae" or "harmful algal blooms", are toxic to plants and animals. Toxic compounds they produce can make their way up the food chain , resulting in animal mortality. [19] Freshwater algal blooms can pose a threat to livestock. When the algae die or are eaten, neuro - and hepatotoxins are released which can kill animals and may pose a threat to humans. [20] [21] An example of algal toxins working their way into humans is the case of shellfish poisoning. [22] Biotoxins created during algal blooms are taken up by shellfish (mussels, oysters), leading to these human foods acquiring the toxicity and poisoning humans. Examples include paralytic , neurotoxic, and diarrhoetic shellfish poisoning. Other marine animals can be vectors for such toxins, as in the case of ciguatera , where it is typically a predator fish that accumulates the toxin and then poisons humans.

Sources of high nutrient runoff Characteristics of point and nonpoint sources of chemical inputs ( [9] modified from Novonty and Olem 1994) Point sources Atmospheric deposition over a water surface Other land activities generating contaminants In order to gauge how to best prevent eutrophication from occurring, specific sources that contribute to nutrient loading must be identified. There are two common sources of nutrients and organic matter: point and nonpoint sources. Point sources Point sources are directly attributable to one influence. In point sources the nutrient waste travels directly from source to water. Point sources are relatively easy to regulate. Nonpoint sources Nonpoint source pollution (also known as 'diffuse' or 'runoff' pollution) is that which comes from ill-defined and diffuse sources. Nonpoint sources are difficult to regulate and usually vary spatially and temporally (with season , precipitation , and other irregular events ). It has been shown that nitrogen transport is correlated with various indices of human activity in watersheds, [23] [24] including the amount of development. [18] Ploughing in agriculture and development are activities that contribute most to nutrient loading.

There are three reasons that nonpoint sources are especially troublesome: [16] Soil retention Nutrients from human activities tend to accumulate in soils and remain there for years. It has been shown [25] that the amount of phosphorus lost to surface waters increases linearly with the amount of phosphorus in the soil. Thus much of the nutrient loading in soil eventually makes its way to water. Nitrogen, similarly, has a turnover time of decades or more. Runoff to surface water and leaching to groundwater Nutrients from human activities tend to travel from land to either surface or ground water. Nitrogen in particular is removed through storm drains , sewage pipes, and other forms of surface runoff . Nutrient losses in runoff and leachate are often associated with agriculture . Modern agriculture often involves the application of nutrients onto fields in order to maximise production. However, farmers frequently apply more nutrients than are taken up by crops [26] or pastures. Regulations aimed at minimising nutrient exports from agriculture are typically far less stringent than those placed on sewage treatment plants [9] and other point source polluters. It should be also noted that lakes within forested land are also under surface runoff influences.

Runoff can wash out the mineral nitrogen and phosphorus from detritus and in consequence supply the water bodies leading to slow, natural eutrophication. [27] Atmospheric deposition Nitrogen is released into the air because of ammonia volatilization and nitrous oxide production. The combustion of fossil fuels is a large human-initiated contributor to atmospheric nitrogen pollution. Atmospheric deposition (e.g., in the form of acid rain ) can also affect nutrient concentration in water, [28] especially in highly industrialized regions. Other causes Any factor that causes increased nutrient concentrations can potentially lead to eutrophication. In modeling eutrophication, the rate of water renewal plays a critical role; stagnant water is allowed to collect more nutrients than bodies with replenished water supplies. It has also been shown that the drying of wetlands causes an increase in nutrient concentration and subsequent eutrophication blooms. [29] Prevention and reversal Eutrophication poses a problem not only to ecosystems , but to humans as well. Reducing eutrophication should be a key concern when considering future policy, and a sustainable solution for everyone, including farmers and ranchers, seems feasible.

While eutrophication does pose problems, humans should be aware that natural runoff (which causes algal blooms in the wild) is common in ecosystems and should thus not reverse nutrient concentrations beyond normal levels. Effectiveness Cleanup measures have been mostly, but not completely, successful. Finnish phosphorus removal measures started in the mid-1970s and have targeted rivers and lakes polluted by industrial and municipal discharges. These efforts have had a 90% removal efficiency. [30] Still, some targeted point sources did not show a decrease in runoff despite reduction efforts. Minimizing nonpoint pollution: future work Nonpoint pollution is the most difficult source of nutrients to manage. The literature suggests, though, that when these sources are controlled, eutrophication decreases. The following steps are recommended to minimize the amount of pollution that can enter aquatic ecosystems from ambiguous sources. Riparian buffer zones Studies show that intercepting non-point pollution between the source and the water is a successful means of prevention. [9] Riparian buffer zones are interfaces between a flowing body of water and land, and have been created near waterways in an attempt to filter pollutants; sediment and nutrients are deposited here instead of in water.

Creating buffer zones near farms and roads is another possible way to prevent nutrients from traveling too far. Still, studies have shown [31] that the effects of atmospheric nitrogen pollution can reach far past the buffer zone. This suggests that the most effective means of prevention is from the primary source. Prevention policy Laws regulating the discharge and treatment of sewage have led to dramatic nutrient reductions to surrounding ecosystems, [16] but it is generally agreed that a policy regulating agricultural use of fertilizer and animal waste must be imposed. In Japan the amount of nitrogen produced by livestock is adequate to serve the fertilizer needs for the agriculture industry. [32] Thus, it is not unreasonable to command livestock owners to clean up animal waste—which when left stagnant will leach into ground water. Policy concerning the prevention and reduction of eutrophication can be broken down into four sectors: Technologies, public participation, economic instruments, and cooperation. [33] The term technology is used loosely, referring to a more widespread use of existing methods rather than an appropriation of new technologies. As mentioned before, nonpoint sources of pollution are the primary contributors to eutrophication, and their effects can be easily minimized through common agricultural practices.

Reducing the amount of pollutants that reach a watershed can be achieved through the protection of its forest cover, reducing the amount of erosion leeching into a watershed. Also, through the efficient, controlled use of land using sustainable agricultural practices to minimize land degradation, the amount of soil runoff and nitrogen-based fertilizers reaching a watershed can be reduced. [34] Waste disposal technology constitutes another factor in eutrophication prevention. Because a major contributor to the nonpoint source nutrient loading of water bodies is untreated domestic sewage, it is necessary to provide treatment facilities to highly urbanized areas, particularly those in underdeveloped nations, in which treatment of domestic waste water is a scarcity. [35] The technology to safely and efficiently reuse waste water, both from domestic and industrial sources, should be a primary concern for policy regarding eutrophication. The role of the public is a major factor for the effective prevention of eutrophication. In order for a policy to have any effect, the public must be aware of their contribution to the problem, and ways in which they can reduce their effects.

Programs instituted to promote participation in the recycling and elimination of wastes, as well as education on the issue of rational water use are necessary to protect water quality within urbanized areas and adjacent water bodies. Economic instruments, “which include, among others, property rights, water markets, fiscal and financial instruments, charge systems and liability systems, are gradually becoming a substantive component of the management tool set used for pollution control and water allocation decisions." [33] Incentives for those who practice clean, renewable, water management technologies are an effective means of encouraging pollution prevention. By internalizing the costs associated with the negative effects on the environment, governments are able to encourage a cleaner water management. Because a body of water can have an effect on a range of people reaching far beyond that of the watershed, cooperation between different organizations is necessary to prevent the intrusion of contaminants that can lead to eutrophication. Agencies ranging from state governments to those of water resource management and non-governmental organizations, going as low as the local population, are responsible for preventing eutrophication of water bodies. Nitrogen testing and modeling Soil Nitrogen Testing (N-Testing) is a technique that helps farmers optimize the amount of fertilizer applied to crops.

By testing fields with this method, farmers saw a decrease in fertilizer application costs, a decrease in nitrogen lost to surrounding sources, or both. [36] By testing the soil and modeling the bare minimum amount of fertilizer needed, farmers reap economic benefits while reducing pollution. Organic farming There has been a study that found that organically fertilized fields "significantly reduce harmful nitrate leaching" over conventionally fertilized fields. [37] However, a more recent study found that eutrophication impacts are in some cases higher from organic production than they are from conventional production. [38] Phycoremediation Manipulating the type of phytoplankton that grow in eutrophic waters is a possible solution to eutrophication. Diatom Algae are good food for zooplankton and fish, hence they consume the nutrients and send them up the food chain. Cyanobacteria are not good food for zooplankton and fish, hence they die and decompose and the nutrients are retained in the water. Therefore causing Diatoms to grow in lakes and rivers is a possible Phycoremediation solution to prevent accumulation of nutrients.

[39] Cultural eutrophication Cultural eutrophication is the process that speeds up natural eutrophication because of human activity. [40] Due to clearing of land and building of towns and cities, land runoff is accelerated and more nutrients such as phosphates and nitrate are supplied to lakes and rivers, and then to coastal estuaries and bays. Extra nutrients are also supplied by treatment plants, golf courses, fertilizers, and farms. These nutrients result in an excessive growth of plant life known as an algal bloom . This can change a lake's natural food web, and also reduce the amount of dissolved oxygen in the water for organisms to breathe. Both these things cause animal and plant death rates to increase as the plants take in poisonous water while the animals drink the poisoned water. This contaminates water, making it undrinkable, and sediment quickly fills the lake. Cultural eutrophication is a form of water pollution . Cultural eutrophication also occurs when excessive fertilizers run into lakes and rivers. This encourages the growth of algae (algal bloom) and other aquatic plants . Following this, overcrowding occurs and plants compete for sunlight, space and oxygen.

Overgrowth of water plants also blocks sunlight and oxygen for aquatic life in the water, which in turn threatens their survival. Algae also grows easily, thus threatening other water plants no matter whether they are floating, half-submerged, or fully submerged. Not only does this cause algal blooming, it can cause an array of more long term effects on the water such as damage to coral reefs and deep sea animal life. It also speeds up the damage of both marine and also affects humans if the effects of algal blooming is too drastic. Fish will die and there will be lack of food in the area. Nutrient pollution is a major cause of algal blooming, and should be minimized. See also References ^ Over fertilization of the World's Freshwaters and Estuaries. University of Alberta Press. p. 1. ^ Hochanadel, Dave (December 10, 2010). "Limited amount of total phosphorus actually feeds algae, study finds" . Lake Scientist. . Retrieved June 10, 2012.

"[B]ioavailable phosphorus – phosphorus that can be utilized by plants and bacteria – is only a fraction of the total, according to Michael Brett, a UW engineering professor ..." ^ Bartram, J., Wayne W. Carmichael, Ingrid Chorus, Gary Jones, and Olav M. Skulberg. 1999. Chapter 1. Introduction, In: Toxic Cyanobacteria in Water: A guide to their public health consequences, monitoring and management. World Health Organization . URL: WHO document ^ Rodhe, W. 1969 Crystallization of eutrophication concepts in North Europe. In: Eutrophication, Causes, Consequences, Correctives. National Academy of Sciences, Washington D.C., Standard Book Number 309-01700-9, 50-64. ^ ILEC/Lake Biwa Research Institute [Eds]. 1988-1993 Survey of the State of the World's Lakes. Volumes I-IV. International Lake Environment Committee, Otsu and United Nations Environment Programme, Nairobi. ^ Walker, I. R. 2006. Chironomid overview.

pp.360-366 in S.A. EIias (ed.) Encyclopedia of Quaternary Science, Vo1. 1, Elsevier, ^ Whiteside. M. C. 1983. The mythical concept of eutrophication. Hydrobiologia 103, 107-111. Eutrophication. What is eutrophication?  The addition of nutrients to an aquatic ecosystem which causes an increased growth of autotrophs. - ppt download Download Presentation is loading. Please wait. Eutrophication. What is eutrophication?  The addition of nutrients to an aquatic ecosystem which causes an increased growth of autotrophs. Published by Antony Davis Modified about 1 year ago Embed Similar presentations More Presentation on theme: "Eutrophication. What is eutrophication?  The addition of nutrients to an aquatic ecosystem which causes an increased growth of autotrophs."— Presentation transcript: 1 Eutrophication 2 What is eutrophication?  The addition of nutrients to an aquatic ecosystem which causes an increased growth of autotrophs.

3  Eutrophication can be a natural process of an aging lake. It happens when the nutrients added are greater than the nutrients used.  To be eutrophic means to be full of nutrients.  It is not always a bad thing for a lake to be eutrophic. Natural Eutrophication takes centuries to occur! Why does it occur? 4 The Human Effect  When humans add nutrients to a lake, and its inhabitants eventually suffer, this is called Artificial/Cultural Eutrophication.  The input of nutrients increases far beyond what the natural capacity of the lake should be. Cootes Paradise Google Earth July 2009 5 Top 4 Artificial Nutrient Sources: 1.Partially treated and untreated sewage (phosphates) 2.Runoff from agricultural sites (nitrates) 3.Home lawn fertilizer use. (nitrates) 4.Home detergent use (phosphates) and chemical fertilizers has greatly increased the amount of nitrates and phosphates that are washed into our lakes and ponds.

6 The Eutrophication Process 1.29min  When phosphates and nitrates are added, the plants begin to grow explosively and algae takes off, or “blooms”.  Plants and algae consume greater amounts of oxygen in the water, robbing fish and other species of necessary oxygen.  The algae dies and falls to the bottom of the lake, bacteria decompose the plants (which requires oxygen).  The lack of oxygen results in the death of biotic factors below the surface of the water.  The cycle continues until the lake dies and… 7  The lake eventually fills in. 8 1. Nutrients added 2. Plants fertilized, increased growth 3. Plants increase, causing decreased light 4. Plants die, then decompose, causing decreased oxygen 5. Low oxygen, animals die 6. More decomposing plants and animals, less oxygen – continues until… The lake is dead except for surface plants 9 What can we do?  Reducing eutrophication should be a key concern when considering future laws and regulations  Sustainable solutions for everyone, including farmers and ranchers  Use phosphate-free soaps  ??? Ideas ???

10 Canada moves to cut phosphates to fight algae problem Last Updated: Saturday, February 16, 2008 | 7:43 PM ET CBC News The federal government has announced it will further limit the use of phosphates in household detergents to help control harmful blue-green algae growth in Canadian lakes and waterways. By 2010, all laundry and dishwasher detergents, and "if warranted" in some general household cleaners sold in Canada, will contain no more than 0.5 per cent phosphates by weight, federal Environment Minister John Baird said Friday in Montreal. At the moment, the phosphorus limit in laundry detergent is 2.2 per cent.CBC News

Question: Eutrophication is the addition of natural or artificial nutrients to what, causing plant growth?
Answer: Water