WHAT IS A COASTAL ZONE?
A coastal zone is often described as the coastal ocean and the land adjacent. It covers approximately 7% (26x106 km2) of the surface of the interface between land and ocean. Despite its relatively modest surface area, a coastal zone is one of the most geochemically and biologically active areas in the biosphere. For example, it accounts for at least 15% of oceanic primary production; 80% of organic matter burial; 90% of sedimentary mineralization; and 50% of the deposition of calcium carbonate. It also represents 90% of the world fish catch and its overall economic value has been recently estimated as at least 40 % of the value of the world's ecosystem services and natural capital. Additionally, coastal areas contain high proportion of the faunal and floristic biodiversity. However, this region is changing rapidly as a consequence of human influence; about 40% of the world's population lives within 100 km of the coastline. As a result, our goal is to create solutions that would mitigate the effects of these negative influences on coastal habitats and wild fish stocks. (Gattuso et al. 2007)
WHAT IS THE PROBLEM?
The water on earth is a constantly changing, dynamic system; what happens in one waterway later flows into downstream waters and into the ocean. The impacts of coastal zones on marine ecosystems and fisheries is profound, not only because of the incredibly biodiveristy and biomass in coastal waters, but also because of the various ecostystem functions that coastal areas provide. Coastal and estuarine areas are often critical spawning and recruitment grounds; damages to the ecosystem and to fisheries there can have wide-ranging effects on the population elsewhere. Furthermore, many fish migrate upstream into freshwaters to spawn (anadromous fish, like shad) or live in freshwater and spawn in the ocean (catadromous fish, like eels); changes in water quality or physical habitat can destroy these populations by decimating their reproductive capacity. The connections between freshwater, estuarine, and marine areas are many and are not yet fully understood. As such, our group proposes to maximize habitat and water quality in these areas so as to minimize fishery mortality from environmental factors. Several problems were identified as the main threats to marine ecosystems in coastal areas; they are:
(1) dams
(2) runoff pollution, including fertilizers (causal agent of eutrophication), sediments, and industrial pollutants
(3) habitat destruction
...
(1) DAMS
I. Significance:
Humans need fifty liters of water per person per day on average (WCD). Less than .007% of the water on earth is liquid freshwater that is regularly cycled and renewed (Human Appropriation).
The world population is increasing at an unprecedented rate and urbanization is occurring at a similarly impressive scale. These increases will result in a larger demand for limited water resources; due to uneven water distribution, it is expected that one-third of water stressed countries will experience severe water shortages in the next century (WCD). Currently, most water is used for agricultural use, especially in developing countries. Currently, dams are a major factor in obtaining the water we so desperately need.
In the 1970's, there was a major boom in dam construction, especially in China, the United States, Japan, Spain, and India (WCD). Currently, of the thousands of large dams (defined by the International Commission on Large Dams as dams with a head height of over fifteen meters) 2/3 are in developing countries (WCD). These dams fulfill a variety of functions including but not limited to water storage, hydroelectric power generation, and flood control. The figure at the right shows the distribution of dams by the their functions (Source: WCD). One third of countries rely on hydropower for over half their energy needs (WCD). Overall, it is easy to see the incredible importance and economic impact of dams. However, there are many environmental and social problems associated with dams. Dams have a significant impact on the marine fisheries, either directly through destruction of spawning habitat or blocking migration or indirectly by increasing pressures on marine fisheries.
II. Issues:
Of the several problems associated with large dams, they can be broken into several categories:
1) Changes to the chemical and physical properties of a river
2) Biotic changes to the ecosystem resulting from the aforementioned riverine changes
3) Human impact due to change in either the river or ecosystem
According to the World Commission on Dams, 46% of the 106 primary watersheds on earth are affected by dams. These effects can included temperature changes (water held in a reservoir warms, while water which is released over the dam's head is cooled), dissolved oxygen level changes (again, the warmer water in a dam's reservoir will have lower DO levels resulting from higher water temperatures and slower water velocity, while water below the dam may become super-saturated with oxygen and poison fish). These changes often favor invasive species, which can then outcompete the native biota. Dams also change the natural flow regimes, which are important triggers for biological cycles. Flow levels can enhance or suppress reproductive success for many species, as well functioning in redistribution of substrates and bed-loads (Young). The WCD reports that in many cases wetlands may dry out and recharge of groundwater is diminished. Besides "trapping" water behind them, dams also act as particle traps, holding back nutrients and sediment. The downstream ecosystems that rely on these nutrients can suffer severely; the crash of Kokanee salmon was attributed to the drastic decrease in nutrient loading caused by the construction of two dams (Wuest). The changes in sediment transport can heavily influence the channel, floodplain, and delta morphology. In coastal areas, the erosion caused by waves is no longer counter-acted by deposition on sediment; the WCD reports that the coastline of Togo and Benin has decreased by 10-15 meters per year after the Akosombo Dam on the Volta River was completed. There are indications that this may also result in a lack of floodplain fertility.
One of the largest problems facing biota in face of dams is obstruction to migration; dams provide a large, physical barrier to aquatic passage. Diadromous fish (includes anadromous fish, which live in salt water and spawn in freshwater--such as shad, sturgeon, and salmon-and catadromous fish, which live in freshwater and spawn in salt water--notably eel) are in many cases entirely unable to reach their spawning grounds. Salmon and shad have died out in areas due to dam construction (WCD); in the United States, shad populations rebounded only after extensive stocking and fish passage efforts (Richardson); in the Caspian Sea, sturgeon must be stocked because dams entirely obstruct their reproduction (WCD). Dams can also obstruct the movements of aquatic insects and larval clams (glochidia); reductions in these populations, which serve as food for higher order predators can have chain reaction affects on fish populations. Dams have been reported as the largest cause for freshwater species extinction (WCD). Loss of freshwater species as a food source (6% of fish caught are from freshwater) may result in more pressure being placed on marine species, so it is important to regard the loss of those species as important to overall ability of the ocean to provide fish (WCD). Thus far, it is estimated that 20% of freshwater fish have become extinct, endangered, or threatened in recent years.
However, it is not just by obstructing fish passage that dams affect marine fisheries. Dams have been shown to decrease catches of fish in upstream portions of rivers (ex. Senegral and Niger Rivers, Nile Delta, and Zambezi River) which again may put more stress on marine fisheries (WCD). Downstream, changes in freshwater flows and nutrient levels can influence the estuarine habitats where many marine fish come to spawn. Lowered nutrient levels can result in lowered overall productivity from a diminished food source, as occurred with the Aswan High Dam in Egypt (WCD). Furthermore, increases in salinity from lessened freshwater flows can allow marine predators to invade can lower recruitment rates (WCD). The overall effects of these changes can be significant; in the Zambezi Delta, there is an estimated $10 million loss per year from the shrimp fishery (WCD).
Other problems associated with dams that are not related to fisheries at large but are large-scale impacts of dams, include displacement of native people (40-80 million) and a diminished ability of native people to collect the river's resources (WCD). Dam reservoirs also emit greenhouses gases, at times at levels larger than the area in a pre-dammed state, which can be a factor when dealing with climate change issues and legislation (WCD). It is also notable that in solving these issues, international politics may come heavily into play, as 261 watershed cross political boundaries and water security issues have been heated in the past (WCD).
III. Solutions:
For dams that have not yet been built there are many steps that can be taken to minimize the impacts. First, efforts should be extended to maximize energy and water efficiency as much as possible; in the past, increases in technological efficiency, recycling, enforcement of environmental legislation, and industrial minimization of intensive water use resulted in a water consumption rate increase much lower than the population demand pressure (WCD). This can be seen as a cost effective method, considering that large-scale dam projects require an incredible amount of capital and are usually both over budget and are completed late (WCD). However, if a dam is definitively needed, research should be thoroughly conducted to determine the environmental impacts. The World Commission on Dams reports that many of the negative impacts from dam construction resulted from complications that were unforeseen; it predicts that use of environmental impact assessments could significantly lower these effects (WCD). Furthermore, proper placement of dams (such as on tributaries rather than on a main branch) and the use of minimal numbers of dams on a given river (because multiple dams can have cumulative effects, such as the dams leading to the Aral sea, which decreased water flow to such an extent that an increase in salinity and pollutants caused the entire fishery to collapse at a cost of approximately $1.25-2.5 billion per year) should be legislated by governments as these restrictions can minimize the large-scale negative impacts of large dams (WCD). Once these data are collected, the dam planning may begin; in this way, the dam design can take into account such features as gates that allow managed flood releases on a scale that can mitigate effects to the ecosystem. The use of such managed floods in Kenya has been economically favorable by maintaining sectors of the economy that relied upon flows that would have been blocked entirely by damming (WCD). These floods help to release nutrients and sediments and help lessen the impact of the dam overall (WCD). These managed floods should be tailored to a specific river, as flood cycles are highly unique. It is important, however, that all such planning occurs before dam construction, as post-construction mitigation techniques have not been shown to be effective; the WCD reports rates of 20% effectiveness.
In terms of fish passage, fish passes have a very low success rate currently. In Norway, fish passes report a 26% rate of "good efficiency" and 32% of no success at all (WCD). In many parts of the world, fish passes are not used at all. Also, even with fish passes, fish often suffer from a lack of environmental cues (like currents) that help them find their spawning site (WCD). However, properly designed fish passes (specific to each dam and species of intended use) do hold promise; in Pennsylvania, fish passes were ineffective until tailored to the American shad, at which point they became very helpful in shad restoration (Richardson). Fish hatcheries and stocking may also be required to augment populations until the spawning routine is re-established with the dam in place; successful restoration of American shad and striped bass required such measures (Richardson), and these methods are likewise advocated by the WCD. The creation of artificial wetlands around shallow dam can also help mitigate dam impact by providing new habitat (WCD).
For developed countries with large budgets and effective environmental legislation (such as France and the United States) decommissioning dams is a solution for aiding fish in special habitats (especially salmon) (WCD). While short-term effects of dam removal include large-scale sediment flushing, over relatively short time scales fish will return and spawn in those areas. However, dam removal is costly and must be studied beforehand; in many cases, toxins and chemicals can build up behind dams and the effects of these toxins washing downstream can be severe (Francisco).
Works Cited
Francisco, Edna. "Tales of the Undammed." Science News 10 Apr. 2004. 28 Oct. 2007 <http://www.sciencenews.org/articles/20040410/bob9.asp>.
Human Appropriation of the World's Fresh Water. University of Michigan. 2000. 28 Oct. 2007 <http://www.globalchange.umich.edu/globalchange2/current/lectures/freshwater_supply/freshwater.html>.
Richardson, Carl. "Migratory Fish Restoration." PA Fish and Boat Commission. 2000. PA Fish and Boat Commission. 28 Oct. 2007 <http://www.fish.state.pa.us/anglerboater/2000/maju00/migrestr.pdf>.
World Commission On Dams. Dams and Development: a New Framework for Decision Making. World Commission on Dams. London: Earthscan Publications Ltd., 2000. 28 Oct. 2007 <http://www.dams.org>.
Wuest, Alfred, Lorenz Moosmann, and Gabriela Friedl. "Alpine Hydroelectric Power Plants and the "Long-Range Effects" on Downstream Waters." EAWAG 55. 17 Oct. 2007 <http://www.eawag.ch/publications/eawagnews/www_en55/en55e_screen/en55e_wuest_s.pdf>.
Young, Leroy M. Fish Habitat and Flow: What's the Connection. PA Fish and Boat Commission. PA Fish and Boat Commission, 1997. 28 Oct. 2007 http://www.fish.state.pa.us/anglerboater/2001/ma2001/habtflow.htm.
...
(2) Runoff Pollutants
Sediments: Sedimentation also has adverse effects on marine habitats and fish stocks. The sediments decrease the penetration of light into the water, which affects fish feeding and schooling practices, and can lead to reduced survival. Suspended sediments in high concentrations also irritate the gills of fish, and can cause death. In addition, they destroy the protective mucous covering the eyes and scales of fish, making them more susceptible to infection and disease. A high concentration of sediments also dislodges plants, invertebrates, and insects in the delta bed. This affects the food source of fish, and can result in smaller and fewer fish. Moreover, settling sediments can bury and suffocate fish eggs. They carry toxic agricultural and industrial compounds as well. If these toxins remain in the coastal areas they can cause abnormalities or death in the fish. (Environment Canada 2001)
Nutrients: Nutrients are required by aquatic ecosystems for primary production; plants, often algae, absorb these nutrients and use them to grow. These plants form the base of the food chain in aquatic ecosystems. However, excess nutrients, especially nitrogen are carried by runoff from agricultural areas and cause a phenomenon called eutrophication. The nutrients over fertilize the ecosystem and cause an explosion in algae population--an algal bloom. When this huge mass of algae dies, however, it consumes oxygen in its decomposition, lowering the dissolved oxygen content for the waterway in general. Eutrophication has been a major problem in estuarine areas, like the Chesapeake Bay in Maryland, USA and continues to be a problem in freshwater lakes and ponds as well.
Heavy metals, industrial toxins, pesticides, and pharmaceuticals: There are a variety of other toxins that can harm fish, even in small quantities. Heavy metals, such as iron, lead, mercury, aluminum, and magnesium are toxic to fish, especially at low pHs. Other toxins, such as PCBs and chlordane are also toxic and tend to bioaccumulate, meaning they build up in members higher in the food chain so that large fish have high levels of these contaminants in their fatty tissue. Not only is this detrimental for fish and ecosystem health, but it is also a danger to consumers, who can also take up the toxins. Health advisories are in place in many parts of the United States for high levels of mercury, PCBs, and chlordane in many fish and other aquatic species ( see state fishing regulations). However, other contaminants that may seem innocuous, like pesticides, can have severe effects of aquatic ecosystems, by poisoning the most sensitive organisms. There is also evidence that pharmaceutical products, especially hormones, in the water has been causing health problems in many species. The source of these toxins is either from direct dumping by companies or individuals (point-source) or by runoff, which picks up the contaminants and carries them into the water during precipitation events (non-point source).
Habitat destruction:
DAMS
I. Significance:
Humans need fifty liters of water per person per day on average (WCD). Less than .007% of the water on earth is liquid freshwater that is regularly cycled and renewed (Human Appropriation).
The world population is increasing at an unprecedented rate and urbanization is occurring at a similarly impressive scale. These increases will result in a larger demand for limited water resources; due to uneven water distribution, it is expected that one-third of water stressed countries will experience severe water shortages in the next century (WCD). Currently, most water is used for agricultural use, especially in developing countries. Currently, dams are a major factor in obtaining the water we so desperately need.
In the 1970's, there was a major boom in dam construction, especially in China, the United States, Japan, Spain, and India (WCD). Currently, of the thousands of large dams (defined by the International Commission on Large Dams as dams with a head height of over fifteen meters) 2/3 are in developing countries (WCD). These dams fulfill a variety of functions including but not limited to water storage, hydroelectric power generation, and flood control. The figure at the right shows the distribution of dams by the their functions (Source: WCD). One third of countries rely on hydropower for over half their energy needs (WCD). Overall, it is easy to see the incredible importance and economic impact of dams. However, there are many environmental and social problems associated with dams. Dams have a significant impact on the marine fisheries, either directly through destruction of spawning habitat or blocking migration or indirectly by increasing pressures on marine fisheries.
II. Issues:
Of the several problems associated with large dams, they can be broken into several categories:
1) Changes to the chemical and physical properties of a river
2) Biotic changes to the ecosystem resulting from the aforementioned riverine changes
3) Human impact due to change in either the river or ecosystem
According to the World Commission on Dams, 46% of the 106 primary watersheds on earth are affected by dams. These effects can included temperature changes (water held in a reservoir warms, while water which is released over the dam's head is cooled), dissolved oxygen level changes (again, the warmer water in a dam's reservoir will have lower DO levels resulting from higher water temperatures and slower water velocity, while water below the dam may become super-saturated with oxygen and poison fish). These changes often favor invasive species, which can then outcompete the native biota. Dams also change the natural flow regimes, which are important triggers for biological cycles. Flow levels can enhance or suppress reproductive success for many species, as well functioning in redistribution of substrates and bed-loads (Young). The WCD reports that in many cases wetlands may dry out and recharge of groundwater is diminished. Besides "trapping" water behind them, dams also act as particle traps, holding back nutrients and sediment. The downstream ecosystems that rely on these nutrients can suffer severely; the crash of Kokanee salmon was attributed to the drastic decrease in nutrient loading caused by the construction of two dams (Wuest). The changes in sediment transport can heavily influence the channel, floodplain, and delta morphology. In coastal areas, the erosion caused by waves is no longer counter-acted by deposition on sediment; the WCD reports that the coastline of Togo and Benin has decreased by 10-15 meters per year after the Akosombo Dam on the Volta River was completed. There are indications that this may also result in a lack of floodplain fertility.
One of the largest problems facing biota in face of dams is obstruction to migration; dams provide a large, physical barrier to aquatic passage. Diadromous fish (includes anadromous fish, which live in salt water and spawn in freshwater--such as shad, sturgeon, and salmon-and catadromous fish, which live in freshwater and spawn in salt water--notably eel) are in many cases entirely unable to reach their spawning grounds. Salmon and shad have died out in areas due to dam construction (WCD); in the United States, shad populations rebounded only after extensive stocking and fish passage efforts (Richardson); in the Caspian Sea, sturgeon must be stocked because dams entirely obstruct their reproduction (WCD). Dams can also obstruct the movements of aquatic insects and larval clams (glochidia); reductions in these populations, which serve as food for higher order predators can have chain reaction affects on fish populations. Dams have been reported as the largest cause for freshwater species extinction (WCD). Loss of freshwater species as a food source (6% of fish caught are from freshwater) may result in more pressure being placed on marine species, so it is important to regard the loss of those species as important to overall ability of the ocean to provide fish (WCD). Thus far, it is estimated that 20% of freshwater fish have become extinct, endangered, or threatened in recent years.
However, it is not just by obstructing fish passage that dams affect marine fisheries. Dams have been shown to decrease catches of fish in upstream portions of rivers (ex. Senegral and Niger Rivers, Nile Delta, and Zambezi River) which again may put more stress on marine fisheries (WCD). Downstream, changes in freshwater flows and nutrient levels can influence the estuarine habitats where many marine fish come to spawn. Lowered nutrient levels can result in lowered overall productivity from a diminished food source, as occurred with the Aswan High Dam in Egypt (WCD). Furthermore, increases in salinity from lessened freshwater flows can allow marine predators to invade can lower recruitment rates (WCD). The overall effects of these changes can be significant; in the Zambezi Delta, there is an estimated $10 million loss per year from the shrimp fishery (WCD).
Other problems associated with dams that are not related to fisheries at large but are large-scale impacts of dams, include displacement of native people (40-80 million) and a diminished ability of native people to collect the river's resources (WCD). Dam reservoirs also emit greenhouses gases, at times at levels larger than the area in a pre-dammed state, which can be a factor when dealing with climate change issues and legislation (WCD). It is also notable that in solving these issues, international politics may come heavily into play, as 261 watershed cross political boundaries and water security issues have been heated in the past (WCD).
III. Solutions:
For dams that have not yet been built there are many steps that can be taken to minimize the impacts. First, efforts should be extended to maximize energy and water efficiency as much as possible; in the past, increases in technological efficiency, recycling, enforcement of environmental legislation, and industrial minimization of intensive water use resulted in a water consumption rate increase much lower than the population demand pressure (WCD). This can be seen as a cost effective method, considering that large-scale dam projects require an incredible amount of capital and are usually both over budget and are completed late (WCD). However, if a dam is definitively needed, research should be thoroughly conducted to determine the environmental impacts. The World Commission on Dams reports that many of the negative impacts from dam construction resulted from complications that were unforeseen; it predicts that use of environmental impact assessments could significantly lower these effects (WCD). Furthermore, proper placement of dams (such as on tributaries rather than on a main branch) and the use of minimal numbers of dams on a given river (because multiple dams can have cumulative effects, such as the dams leading to the Aral sea, which decreased water flow to such an extent that an increase in salinity and pollutants caused the entire fishery to collapse at a cost of approximately $1.25-2.5 billion per year) should be legislated by governments as these restrictions can minimize the large-scale negative impacts of large dams (WCD). Once these data are collected, the dam planning may begin; in this way, the dam design can take into account such features as gates that allow managed flood releases on a scale that can mitigate effects to the ecosystem. The use of such managed floods in Kenya has been economically favorable by maintaining sectors of the economy that relied upon flows that would have been blocked entirely by damming (WCD). These floods help to release nutrients and sediments and help lessen the impact of the dam overall (WCD). These managed floods should be tailored to a specific river, as flood cycles are highly unique. It is important, however, that all such planning occurs before dam construction, as post-construction mitigation techniques have not been shown to be effective; the WCD reports rates of 20% effectiveness.
In terms of fish passage, fish passes have a very low success rate currently. In Norway, fish passes report a 26% rate of "good efficiency" and 32% of no success at all (WCD). In many parts of the world, fish passes are not used at all. Also, even with fish passes, fish often suffer from a lack of environmental cues (like currents) that help them find their spawning site (WCD). However, properly designed fish passes (specific to each dam and species of intended use) do hold promise; in Pennsylvania, fish passes were ineffective until tailored to the American shad, at which point they became very helpful in shad restoration (Richardson). Fish hatcheries and stocking may also be required to augment populations until the spawning routine is re-established with the dam in place; successful restoration of American shad and striped bass required such measures (Richardson), and these methods are likewise advocated by the WCD. The creation of artificial wetlands around shallow dam can also help mitigate dam impact by providing new habitat (WCD).
For developed countries with large budgets and effective environmental legislation (such as France and the United States) decommissioning dams is a solution for aiding fish in special habitats (especially salmon) (WCD). While short-term effects of dam removal include large-scale sediment flushing, over relatively short time scales fish will return and spawn in those areas. However, dam removal is costly and must be studied beforehand; in many cases, toxins and chemicals can build up behind dams and the effects of these toxins washing downstream can be severe (Francisco).
Works Cited
Francisco, Edna. "Tales of the Undammed." Science News 10 Apr. 2004. 28 Oct. 2007 <http://www.sciencenews.org/articles/20040410/bob9.asp>.
Human Appropriation of the World's Fresh Water. University of Michigan. 2000. 28 Oct. 2007 <http://www.globalchange.umich.edu/globalchange2/current/lectures/freshwater_supply/freshwater.html>.
Richardson, Carl. "Migratory Fish Restoration." PA Fish and Boat Commission. 2000. PA Fish and Boat Commission. 28 Oct. 2007 <http://www.fish.state.pa.us/anglerboater/2000/maju00/migrestr.pdf>.
World Commission On Dams. Dams and Development: a New Framework for Decision Making. World Commission on Dams. London: Earthscan Publications Ltd., 2000. 28 Oct. 2007 <http://www.dams.org>.
Wuest, Alfred, Lorenz Moosmann, and Gabriela Friedl. "Alpine Hydroelectric Power Plants and the "Long-Range Effects" on Downstream Waters." EAWAG 55. 17 Oct. 2007 <http://www.eawag.ch/publications/eawagnews/www_en55/en55e_screen/en55e_wuest_s.pdf>.
Young, Leroy M. Fish Habitat and Flow: What's the Connection. PA Fish and Boat Commission. PA Fish and Boat Commission, 1997. 28 Oct. 2007 http://www.fish.state.pa.us/anglerboater/2001/ma2001/habtflow.htm.
Riparian Buffers
Importance:
...