quinta-feira, 25 de fevereiro de 2016


The Dollars and Sense of Wetland Preservation

Wetlands are crucial for the maintenance of a healthy environment and the provision of clean, useable water for human and ecosystem use. They are incredibly productive areas containing an abundance of biodiversity. They are natural buffers that reduce the occurrences of floods and droughts. And, they are critical breeding and nursery grounds for aquatic and terrestrial species.
But wetlands have been systematically altered, developed, destroyed, and lost all over the world. Over the last century, an estimated 64% of wetlands have been lost. If they are so important, then why are they not being preserved? Perhaps some people need better, or at least different reasons to save them.
A big motivating factor for many people would be economic reasons. But can arguments be made to convince these people it is in their best interests to protect wetlands? The answer is a resounding yes. All over the world, people are finding out that wetland preservation not only makes sense, but can make dollars as well.
A study assessed the value of wetlands taking into account their many functions. It was determined that the world’s wetlands – including freshwater and saltwater ecosystems – are worth US$14.9 trillion. This figure represents 45 percent of the total value of all ecosystems, demonstrating that wetlands are incredibly valuable areas.
Flood Control
Wetlands are natural flood control systems. They are effective at storing and slowly releasing floodwater, thereby preventing flood-related damage. A U.S. study determined that 0.4 hectares of wetland has the capacity to store more than 6,000 m3 of water. Utilizing wetlands for flood control prevents the need to construct expensive flood control structures.
The following are examples of the value of wetlands in controlling floods:
  • U.S.A.: The Charles River has 3,800 hectares of intact wetlands along its banks. It has been estimated that flood damages would amount to US$17 million per year if the wetlands were destroyed.
  • U.S.A.: The Mississippi River has undergone extensive modifications in an attempt to control flooding, including the construction of many engineered structures and the destruction of 6.9 million hectares of wetlands. The modifications did not prevent flood damage. The 1993 flood alone caused US$12-16 billion in flood-related damages.
  • China: Deforestation, loss of wetlands due to agricultural development, and residential development in flood plains has caused an increase in the number of devastating floods. Damages for the 1998 flood alone amounted to US$32 billion. In order to prevent future devastation, China is working to restore wetland areas and is putting an end to the clearing of trees in the watersheds.
  • Europe: Repeated flooding of the Rhine River has prompted governments in the affected countries to restore the river’s flood plains and wetlands.

Retention of sediments and nutrients, and recharging groundwater aquifers are only a few of the benefits of healthy wetland ecosystems.

Groundwater Replenishment
Groundwater is important for both human and ecosystem requirements. Billions of people rely on it for domestic, industrial, and agricultural needs. All over the world, groundwater aquifers are being depleted due to over-use. Many wetlands recharge aquifers, which makes them extremely valuable for the maintenance of groundwater levels.
Some examples of the importance of groundwater replenishment by wetlands:
  • Tunisia: During times of flood, the Zeroud, Merguellil, and Nebaana Rivers recharge the aquifer. Even though these rivers go dry for part of the year, the recharged aquifer is able to supply irrigation water all year.
  • Crete: Streambeds in the Messara Valley supply about half of the water necessary to recharge the aquifer, thereby supplying water for irrigation.
  • U.S.A.: The recharge and storage functions of a 223,000-hectare swamp in Florida are valued at US$25 million per year.
  • Nigeria: A value of US$4.8 million per year has been placed on the Hadejia-Nguru wetlands, because it recharges the aquifer that many people use as their water source.
  • Tunisia: When the water supply to the Garet El Haouria wetland was altered, its aquifer recharge abilities were cut. This resulted in the depletion of the aquifer due to excessive water removal. Groundwater levels have been steadily falling, and saltwater intrusion has caused the abandonment of some wells.

Coastal wetlands like this mangrove swamp aid in shoreline stabilization, which lessens the effect of storm damage.

Shoreline Stabilization and Storm Protection
Coastal wetlands such as saltmarshes, mangrove swamps, and forested wetlands help to buffer the devastating and costly effects of hurricanes, cyclones, and storm surges, by reducing wind, wave, and current action. The removal of this natural protection increases the occurrences and severity of costly storm-related damage.
Many countries such as Bangladesh, the Philippines, and Thailand have realized the economic benefit of replacing lost coastal wetlands. They have also found it is much less expensive to protect existing wetlands, then to replace them after they have been lost. In Thailand, costs for replanting lost vegetation amounted to US$946 per hectare, while it costs only US$189 per hectare to preserve existing wetland areas.
By considering the costs associated with storm damage, it is easy to see the value of wetland areas. Each kilometer of intact mangrove swamp in Malaysia is valued at US$300,000 for its role in flood and storm protection. Erosion control is another important function of wetland areas. Vegetated riverbanks in England have been valued at US$425 per metre because of this ability.
Sediment and Nutrient Retention
As water passes through wetlands, flow rates are decreased, resulting in the deposition of nutrient-laden sediments. This process produces an incredibly rich and productive ecosystem. In fact, natural wetland areas are often more productive than intensive agricultural operations that utilize irrigation, fertilizers and pesticides.
When wetlands are lost, nutrients are no longer retained, which results in a decrease in productive capacity. In 1979, the Waza-Logone floodplain in Cameroon was severely degraded as a result of the building of a dam and flood control structures. Nutrients were not allowed to deposit in the floodplain, and the area no longer supported the fishing and grazing activities that once sustained 10,000 people. To correct this mistake, the area was restored at a cost of more than US$5 million.
When sediments are prevented from being deposited in river deltas, these once highly productive areas are seriously degraded. The Mississippi delta is being severely impacted by dams and flood control structures. One of the results is the decline in the Louisiana fishing industry, which in 1989 was worth US$264 million.

Healthy wetlands are highly effective at filtering and cleaning water, resulting in a better environment for people and wildlife.

Water Purification
Wetlands are highly effective at treating polluted wastewaters. Excess nutrients from agricultural operations, toxic chemicals, heavy metals, pesticides, oil and grease, and fecal coliforms are all removed by wetland plants and soils. In fact, some wetland plants are so effective at removing toxins, they can have 100,000 times the concentration of heavy metals in their tissues, than in the surrounding water.
Some examples of water treatment by wetlands:
  • Florida, U.S.A.: Wetlands remove 98 percent of nitrogen and 97 percent of phosphorous from wastewater, thereby preventing contamination of the groundwater.
  • West Bengal, India: Wetland plants are effectively treating the 23 million litres of domestic and industrial wastes that flow into the wetland every day. Heavy metals, grease and oil, and 99.9 percent of the fecal coliforms are being removed from the water. In addition to the treatment benefits of the wetland, fishermen are also harvesting one tonne of fish every day.
  • New York City, U.S.A.: The City was looking at investing US$3-8 billion in water treatment plants. Instead, they decided to buy land around their reservoirs for US$1.5 billion, so the water could be filtered by wetlands for free. They also saved the US$700 million per year they would have spent on the treatment plants’ operating expenses.
  • Calcutta, India: The City is utilizing 8,000 hectares of wetlands to treat the sewage and refuse from its 10 million citizens. By using the wetlands for this purpose, they avoid having to build expensive treatment plants. The wetlands also produce 20 tonnes of fish and 150 tonnes of vegetables every day. 

Wetlands are a storehouse of biodiversity, providing habitats for a great variety of aquatic and terrestrial species.


Wetlands are incredibly diverse ecosystems containing a large number of different aquatic and terrestrial species. In fact, freshwater wetlands provide habitats for greater than 40 percent of the earth’s species. This storehouse of biodiversity is not only priceless, but is also essential to our future.

Wetland species are literally a gene pool that not only provide benefits to us now, but will also produce a great number of unknown benefits in the future. An example of this importance is in rice production. In order to continue to fight pests and diseases, commercially produced rice crops must utilize new genetic material every five to ten years. An important source of this genetic material is found in the wild rice varieties that live in wetlands. Rice crops feed more than 50 percent of the world’s people. If the wild rice gene pool is lost due to wetland destruction, the result will not only affect an important food source, but will also severely impact an industry worth billions of dollars.

Some wetland plants and animals are a source for drugs and treatments used in the medical industry. They are also part of the traditional medicine practiced by 80 percent of the world’s population. This wetland ‘pharmacy’ not only holds medicines we use now, but is more importantly a storehouse for an untold number of future treatments yet to be discovered. An example is the South American clawed toad. Researchers are finding that chemicals in its skin may provide a source for antibiotics, fungicides, and anti-viral medications.

Many organizations and individuals promote the preservation of biodiversity. Literally billions of dollars are spent on conservation programs worldwide. This demonstrates that many people put a high dollar value on these fragile ecosystems.

Healthy wetland ecosystems are extremely productive and are capable of providing huge quantities of food and other products.

Wetland Products
As previously mentioned, wetlands are incredibly productive areas. They are the source for a wide range of useful and essential foods and materials. It has been estimated that swamps and marshes alone can produce nine tonnes of protein per square kilometre each year. The economic value of these products amounts to billions of dollars. For example, a one million hectare flooded forest in the Brazilian Amazon produces US$4.4 million worth of fish and other products each year.

Around the world, people are finding out that intact and healthy wetlands can produce more income than using the area and water for other purposes. An economic evaluation was done to determine whether diverting water from Nigeria’s Hadejia-Jama’are wetlands for an irrigation project, would produce more income for the local population, than if the water was left to maintain the wetlands. The fish and other products harvested from the intact floodplain were able to support tens of thousands of people, while the irrigation project was found to contribute far less. The study valued the intact floodplain at US$167 per hectare and the water at US$43 per 1000 m3. This contrasted with the value of the irrigation project, which was US$29 per hectare, and four cents per 1000 m3 for the water value.

Another study done in Thailand showed similar results. By building dams and irrigation systems, as well as using pesticides and fertilizers, it was determined that two crops of rice per year could be produced instead of just one. This would, of course, destroy the area’s wetlands. By leaving the wetlands intact, less rice would be produced, but the local population could harvest fish, shrimp, crabs, bamboo shoots, and mushrooms. The average annual family income for the multi-harvest system was US$2,500-2,950, however, it would be only US$865-1,296 if they were dependent on the two rice crops alone. Saving the wetlands was definitely the best economic decision.

Fish harvesting feeds more than one billion of the world’s population. Healthy wetlands are crucial to the survival of both freshwater and marine fish species. Coastal wetlands are important in the life cycles of two thirds of the marine fish species we consume, and freshwater wetlands are important in maintaining the health of coastal wetlands. The value of wetlands to the entire fishing industry is huge. In the U.S. alone, salmon, crab, and shrimp harvests amounted to US$13 million dollars in 1991. A value of US$4,850 per hectare was given to the mangroves in Australia’s Moreton Bay, due to their importance in the maintenance of the area’s fish industry.

The following is a list of some of the wetland products and foods harvested around the world:
  • Rice: As previously mentioned, this wetland crop feeds three billion people worldwide.
  • Sago Palm: It is an important source of carbohydrates in Asia, and cooking oil in Africa.
  • Nipa Palm: Asian people use it to produce fodder, alcohol, vinegar, and sugar. In fact, its sugar production amounts to three tonnes per hectare.
  • Mangrove trees: It is the source of thatch for roofing materials, fibres for textile and paper production, timber, firewood, medicines, and dyes and tannins for treating leather.
  • Crocodilians (crocodiles, alligators, caimans, and gharials): They are harvested for their meat and skins. The marketing of skins alone amounts to US$500 million each year.
  • Reeds: In Europe, reed harvesting is becoming more popular since it is being used as roofing material. A thatched roof provides better insulation than tiles, and lasts for 25-40 years.
Many countries are finding that healthy wetlands can provide good incomes for local people and help to alleviate poverty. When this can be done in addition to restoring and conserving wetlands, everyone benefits. Projects that promote the sustainable trade of rainforest products are a direct benefit to the local people, thereby helping to alleviate poverty and at the same time preserve the area’s wetlands.

India’s East Calcutta Wetlands mentioned previously, not only help to clean the City’s wastewater, but also provide employment and income to a large number of people. There are 50,000 people directly employed in the production of food and other products from the wetland, and an additional 50,000 who are indirectly employed. The wetlands produce enough food to feed 500,000 people per day.

Wetland restoration projects can also provide much needed employment opportunities. The South African Government’s Working for Water Program has employed 20,000 people. They are working to improve the country’s water supply by eliminating invasive plant species from wetlands.

Many countries are finding that preserving and restoring wetlands makes good economic sense. Activities such as ecotourism can generate millions of dollars for local economies.

Recreation and Tourism

Wetlands are a veritable treasure chest of animal and plant life waiting to be explored, and people are traveling to these sites in record numbers. Tourism and recreational activities are pumping large sums of money into the local economies, further emphasizing the need to protect these areas. Tourist travel to the wetlands of the Florida Keys brings in approximately US$800 million annually. The recreational value of the United Kingdom’s Norfolk Broads wetlands has been estimated at US$32.5 million per year to local residents, and US$12.9 million for those living further away.

Recreational fishing, hunting, and bird watching are popular activities practiced by millions of people. Freshwater and marine fish caught by recreational fisherman need healthy wetlands to survive. In the U.S. alone, the 45 million people who enjoy recreational fishing spend US$24 billion every year. Bird watching is also a popular and growing hobby, and involves more than 60 million people in North America. That combined with the 3.2 million people who hunt ducks and geese, produces US$20 billion annually.

An ever-expanding sector of the tourism industry is ecotourism. In fact, revenue generated by ecotourism is growing by 20 percent every year, making it the fastest growing segment of an industry that generated US$476 billion in 2000 alone. It also employs millions of people worldwide. This is causing many world governments and organizations to look to their natural environments as a potential source of tourist dollars.

According to the World Conservation Union, ecotourism is defined as, “environmentally responsible travel and visitation to relatively undisturbed natural areas, in order to enjoy and appreciate nature (and any accompanying cultural features – both past and present) that promotes conservation, has low negative visitor impacts, and provides for beneficially active socio-economic involvement of local people.” Since ecotourists tend to be in smaller groups, they have less impact on the environment and the local cultures. They also tend to stay longer meaning they spend more money.

This form of travel not only provides local people with much needed income, but also encourages them to take care of and value their environment. This will prompt their governments to look seriously at the economic value of preserving the ecosystems in a natural state. Ecotourism is seen as a way to attract the needed tourist dollars, without the negative impacts mainstream tourism has on the environment and the local population. There are projects being developed in some countries that are attempting to develop wetland areas in order to promote ecotourism. They are beginning to see that healthy, intact wetlands can be economic assets that can generate a great deal of capital.

Wetlands provide many recreational opportunities enjoyed by millions of people, which results in billions of tourism dollars.


The more we study wetlands, the more we see how crucial they are to our very survival and to the well being of the entire planet. Just imagine how much these ecosystems have yet to teach us. Now imagine how much we would lose if they are gone forever. The decision to save wetlands is an easy one to make for many people. Others come around when they are educated about the many natural benefits wetlands provide.

But some people still fail to see how saving wetlands will benefit them personally. Will they provide me with a job and a good income? Will they feed my family? Will they help to free us from poverty and hunger? The answer to all of these and many similar questions is YES! Wetland preservation does indeed make dollars as well as sense.

Rick de Vries is the publisher, editor, and main writer for H2Ozine. He has a background in research and environmental sciences, and has many years of experience writing and editing for environmentally related media.

Fonte: H2Ozine



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