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
I. PROBLEMS--
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).
II. Solutions--
Aside from regulating point source pollutants (i.e. dumping of contaminants into the water), the most effective way to prevent the addition of contaminants is to establish riparian buffers and wetlands to filter and slow runoff before it carries its toxic load into the waterway.
Riparian Buffers
Importance:
Riparian buffers provide various stream functions.
(1) Leaves that fall into the water provide energy for headwaters (i.e. a food source).
(2) Branches and roots provide shelter for in-stream organisms.
(3) Overhead leaf cover shades water and keeps it cool, by as much as 10° in summertime (Great Fishing).
(4) Roots hold stream banks in place and prevent erosion.
(5) Vegetation slows water velocity, thus reducing run-off induced erosion and also allows particulates (including many water contaminants) to settle out.
(6) Soils and root systems filter nutrients and pollutants (especially from agriculture and residential areas) before they reach surface areas from groundwater (Haberstock).
These functions are not only important to the biota that lives in these regions year round, but also to anadromous species that come to spawn. For example, salmon require clean gravel for spawning; if silt settles over the gravel, it not only destroys suitable spawning substrate, but it can also smother eggs and the invertebrates that juveniles feed upon (Haberstock). Haberstock also reports that branches and other woody structures provide places for invertebrate prey to live, as well as structural habitat and varied flow patterns that are important for salmon. The improved water quality provided by riparian buffers and the cooling effect they provide are also critical (Haberstock).
Plan:
Riparian buffers should be established along rivers; the width should be determined based on various criteria as detailed below. To implement this, focus should be placed on education of farmers to take up these measures voluntarily. Governments and agencies that can afford to provide funds to help establish these buffers, offer tax incentives, or to rent land to take it out of production should do so.
The width of the buffer depends on many factors, especially the slope of the land (steeper slopes require wider buffers), the permeability of the soil (less permeable soils require wider buffers because water takes longer to infiltrate), and the presence of overland water sources--like intermittent streams or gullies-which can render small buffers ineffective (Haberstock). The type of vegetation-such as wooded or ground level vegetation--as well as factors such as duff height can influence buffer efficacy (Haberstock). Buffer width is measured from the end of alluvial soils (floodplain edge) (Haberstock). Haberstock also notes that wetlands in these areas should be preserved, because they function more effectively in nitrogen-fixation and retention of contaminants and sediments.
However, if it is not economically feasible to establish a buffer of the recommended width, it is still beneficial to establish a riparian buffer of a smaller width. Studies have found that buffers of 20 feet of native grasses can remove up to 90% of nutrients and 80% of sediments (Lutz). Furthermore, a riparian buffer does not mean that no human activity or industry can take place in these zones; for example, selective logging can take place if best-management practices are followed and some agriculture such as growing nut trees can easily serve as a buffer and a source of income.
Haberstock Recommendations:
Zone 1: 35 feet
Zone 2: For width determinations, see the method outlined in Haberstock pages 8-14. (see attached document)
Works Cited
A Conservation Catalog. Pennsylvania Conservation Partnership. Pennsylvania Conservation Partnership. 29 Oct. 2007 <http://www.envirothonpa.org/documents/conscatalog.pdf>.
Great Fishing Needs Great Habitat. PA Fish and Boat Commission. 1997. 29 Oct. 2007 <http://www.fish.state.pa.us/anglerboater/2001/jf2001/greathab.htm>.
Haberstock, Alan E., et al. "METHOD TO IDENTIFY EFFECTWE RIPARIAN BUFFER WIDTHS FOR ATLANTIC SALMON HABITAT PROTECTION1." Journal of the American Water Resources Association 36.6 (2000): 1271-86.
Lutz, Karl J. A Fish and Livestock Tale. PA Fish and Boat Commission. PA Fish and Boat Commission. 8 Nov. 2007 <http://www.fish.state.pa.us/anglerboater/2001/01_nov-dec/AFishandLivestockTale.pdf>.
The Basics of Water Pollution. PA Fish and Boat Commission. PA Fish and Boat Commission. 29 Oct. 2007 <http://www.fish.state.pa.us/anglerboater/2001/jf2001/waterpoll.pdf>.
Wetlands Importance
Wetlands protect against flooding, they trap sediment, clean water and provide food; however they are constantly being encroached on and disregarded as hindrances to real estate development. They are important for fish health because they reduce the presence of nitrates and increase oxygen levels. Wetlands reduce silt which when it covers fish eggs hinders them from successfully hatching. Wetlands provide a habitat for reproduction, feeding and resting. Perch, pickerel, bass, sunfish, muskellunge, catfish and walleyes breed in wetlands and many are moving towards distinction because of the loss of wetlands. (Dietz, 2007)
The main goal in fixing the current state of minimized wetlands (the original 221 million acres have been reduces to less than half of that) is to reintroduce wetlands to counter the current trend, where every year 290,000 acres are lost (Dietz, 2007). When a wetland contains animals that are on the endangered species, the wetlands that contain them are afforded more protection. Thus getting more fish and wetland dwelling animals on he endangered species list would slow down their decline. Wetlands in the US are minimally protected under the Dam safety and Encroachments Act and the Federal Clean Waters Act under a clause to "Avoid, minimize and compensate". If they are really truly going to be protected there needs to be a greater penalty for encroachment, because the current system which requires payment into a wetlands reestablishment fund does not provide enough because new wetlands are always worse than prexisting wetlands which have masterfully balanced ecosystems (as seen by their survival). There needs to be the introduction of new stricter laws under new sectors of legislation, not just title pieces under preexisting legislation. Finally since the encroachment of a wetland includes a litigation process, lengthening the permit process and requiring more in compensation to the wetlands Replacement Fund will turn away more developers, a huge factor into wetlands loss.
Wetland Tourism
Wetlands ecotourism is a really exciting way to present the problem. It is often hard to appeal scientific facts to a non-scientific world. This idea is very similar to an Inconvenient Truth; the most effective scenes in the documentary are ones that include pictures of the polar ice caps melting and poor baby seals stranded. Also this relates in a way back to Professor Sadaways' lecture that he gave during one of the Terrascope lunches on energy. He made the point that if you continue to sell compromises like Toyota does with there Prius, then you won't fix anything, but if you "sell the best ride of your life" then you have a chance at marketing change. With this same concept we need to sell the beauty of the oceans and wetlands and their importance to our visual hungry culture if we have chance at starting to solve the problem. Strengthening wetland tourism through both education (of both the importance and beauty of wetland) and physical marketing campaigns to specific wetlands such as the Great Barrier Reef, the Mediterranean Coast and the Florida keys (van der Duim, 2007). Not only does this sort of ecotourism benefit the people of the local communities (who benefit from it directly because tourism is based on natural capital) but also on a large enough scale could start to alleviate the need for fishing in poor area as an economic resource. Of course the most direct benefit however will be the new relationship the tourist receives from realizing the significance of the wetland.
International Wetlands
Our goal in creating a more stable and healthier fish population as it pertains to wetlands translates to lessening the rate of depletion of wetlands and restoring needed wetlands on a basis of regional necessity. While the lack of them is common across the globe, the need for specific ones and often the destruction of them due to natural disasters or human interference varies with location. Thus an important compilation of both local task forces, primarily lead by wetlands international (a compilation of regional offices and groups) assisted by and encouraged by laws and regulations is the best solution. Organizations like Wetlands International play a particularly important role in this setup because they both organize the needed local tasks forces and catalyze the political action process. Wetlands International's mission statement serves to clarify its duality in its proposal that it "works in local areas to help create restoration programs combined with stricter enforcement," (Finlayson, 2006). These locally funded projects include rebuilding mangrove forests in South East Asia which were depleted after the Tsunami and their lack has hindered fish populations. In India wetlands and swamps are being illegally logged and drained for agriculture which in addition to their mal effects on the fish populations, is causing wild fires and soil oxidation. Regional task forces are politicking in the legislative process to create harsher penalties for this. In Ukraine, maps were drafted up which led to the establishment of the Dniro eco-corridor. With greater funding companies like Wetlands International can be expanded to serve a greater number of regional areas and additional companies with focuses on litigation, tourism and recovery could also be introduced into the global scheme.
III. Habitat Destruction
Problem:
Conversion of coastal ecosystems for agriculture or aquaculture has adverse effects on marine fisheries because it destroys the habitat of exploited fish stocks. For example, conversion of mangroves in a number of South and South-East Asian countries during the mid 1990s caused an increased risk of diseases in wild stock. It also significantly reduced the recruitment and survival rate of the stocks. Since some 90% of fish stocks depend on coastal habitat for at least parts of their life cycle, this is an issue that should be addressed. (Perrings 2000)
Solutions:
A variety of approaches could be combined more effectively to ensure protection for coastal habitats. The plan should include the establishment of comprehensive wetlands protection policies and programs; wetlands acquisition by federal, state, and local government agencies or private conservation organizations; increased public education; improved standards and policies for agricultural and silvicultural practices; guided investments in public works projects; greater involvement of local governments; designated functional primary nursery areas, including those in inland waters; and financial (tax) incentives for wetlands protection and financial disincentives for wetlands destruction. (UNC) & (Bildstein et al. 1991)
Furthermore, for effective management of coastal fisheries, local spawning and nursery grounds need to be identified (Knutsen 2003). In exploited areas, restrictions on point and nonpoint source pollution (such as sewage and fertilizer runoff) must be passed and enforced. Additionally, population models can be identified to make better regulation. For example, (Rose et al. 2001) suggested a model that categorized freshwater and marine species into three general strategists: opportunistic strategist, equilibrium strategist, and period-life strategists. We have to also keep in mind parameters such as stock biomass, predator consumption, fish mortality and fecundity, and human consumption when devising regulations for management of coastal fisheries (Oguz 2007).We can also create market based instruments for environmental protection in coastal and marine systems. This means assigning property rights (creating markets) and applying taxes, subsidies, user fees and/or charges to address the problem.
Work Cited: Bildstein, Keith L, Bancroft, G Thomas, et al. (1991). Approaches to the Conservation of Coastal Wetlands in the Western Hemisphere. The Wilson Bulletin, 103(2), 218. Retrieved November 2, 2007, from Sciences Module database. (Document ID: 3813300). Environment Canada (2001). Why is sediment important? Retrieved November 2, 2007. URL: http://www.ec.gc.ca/Water/en/nature/sedim/e_effect.htm
Gattuso, Jean-Pierre and Stephen V. Smith (Lead Authors); J. Emmett Duffy (Topic Editor). 2007. "Coastal zone." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington,D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published March 7, 2007; Last revised March 20, 2007; Retrieved October 12, 2007]. <http://www.eoearth.org/article/Coastal_zone> Knutsen, H., Jorde, P. E., Andre, C., & Stenseth, N. C. (2003). Fine-scaled geographical population structuring in a highly mobile marine species: The atlantic cod. Molecular ecology, 12(2), 385-394. Nieminen, M., Ahti, E., Nousiainen, H., Joensuu, S. & Vuollekoski, M. 2005. Capacity of riparian buffer zones to reduce sediment concentrations in discharge from peatlands drained for forestry. Silva Fennica 39(3): 331-339. Oguz, Temel. (2007). Nonlinear response of Black Sea pelagic fish stocks to over-exploitation. <span style="color: black"><strong><span style="text-decoration: line-through; ">Marine Ecology Progress Series,</span></strong></span> 345:211-228. Perrings, Charles (2000). Sustainability indicators for fisheries in integrated coastal area management. Marine and Freshwater Research 51, 513-522. Rose, K. A., Cowan, J. H., Winemiller, K. O., Myers, R. A., & Hilborn, R. (2001). Compensatory density dependence in fish populations: Importance, controversy, understanding and prognosis. Fish and Fisheries, 2(4), 293-327. UniversityofNorth Carolina. Wetland Protection Plan. Retrieved November 2, 2007.
URL: http://ils.unc.edu/parkproject/resource/scorp/scorp_ch6.pdf\\
Finlayson, MAx. (2006). Wetlands International Annual Review 2006.
http://www.wetlands.org/publication.aspx?ID=c76e4f7a-41c5-4aca-9a73-ffc5e69f5d89
van der Duim, R and Henkens, R, Wageningen (2007) Wetlands, poverty reduction and sustainable tourism developement, oppurtunities and constraints.
http://www.wetlands.org/publication.aspx?ID=8d31d63c-edef-4daa-b309-9674d6af52fa
Dietz, Walt. (2007). Wetlands the Vital Link
http://www.fish.state.pa.us/anglerboater/2001/mj2001/vitalink.htm