Wetlands
A habitat is where it's at.
Keep them so the ducks can quack,
The marshes filter the water's dirt,
They're homes for many who we don't want hurt.
Natural Threats
- Erosion
- Subsidence
- Sea level rise
- Droughts
- Hurricanes and other storms
- Drainage - Dredging and stream channelization - Deposition of fill material - Diking and damming - Tilling for crop production - Levees - Logging - Mining - Construction - Runoff - Air and water pollutants - Changing nutrient levels - Releasing toxic chemicals - Introducing nonnative species - Grazing by domestic animals
A salt marsh may not look like a very inviting area. However, these muddy, grassy, areas are among the most biologically productive environments on Earth. The salt marshes of Georgia, for example, produce seven times as much organic matter as a field of wheat.
At the base of the salt-marsh food web is the grass Spartina. Bacteria and fungi feed on the dead plants. Crabs, snails, clams, worms, and birds also inhabit the salt marsh, eating the animals that eat the dead plants.
Land adjoining water has attracted humans for centuries because of the access to ocean transport and resources. Coastal land is beautiful, and I offers many enjoyable activities. To meet the human need for more coastal land, salt marshes are often drained for development. Should salt marshes continue to be drained to meet the growing needs of human populations?
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The land along coastal regions is desirable property for recreation and housing. People enjoy living and vacationing near the water. Salt-marsh sites are crucial areas for industries and nuclear power plants. The land is located near water for shipping. Also, the water is convenient for cooling pipes. Housing, recreational, and industrial development of marsh areas helps the economy by providing employment for millions of people. Real estate along coastal areas generates money. In some areas of the United States, 1 m2 of former salt marsh may sell for as much as $1,000. New salt marshes could be constructed on less valuable land. The salt-marsh species could be relocated to alternative habitats because they have a high tolerance for changes in temperature, salinity, and sediment composition. |
Salt-marsh habitats support many different species of organisms including several endangered species. The restoration or formation of salt marshes on alternative sites is often unsuccessful. The ecology of the salt marsh is not understood well enough to be reproduces artificially. Salt marshes are vital sources of protein for humans because many fish, crabs, oysters, and clams breed and live in the marshes. The draining of the marshes would affect all the people who depend on the productivity of the salt marsh for their livelihood. Salt marshes and their adjoining waters are natural flood-control areas. These zones also block damaging waves, protecting developments built along coasts. Salt marshes filter pollutants from coastal waters. It is estimated that the filtering capacity of 1 acre of marsh is equal to the capacity of a waste-treatment plant. Bernstein, Winkler, Zierdt-Warshaw. Environmental Science, Ecology and Human Impact. Addison-Wesley, New York, NY (1996). P177. |
Could the 'Cell from Hell' Threaten Your Fishing?
WRITTEN BY FRANK CALIA
Last summer the nation witnessed what seemed like the plot of a grade-B Hollywood thriller played out in news headlines: A microscopic horror had emerged from the quiet waters of East Coast rivers to dissolve and feed on fish flesh, inflicting ghastly wounds and killing fish by the thousand.
But this was no screenwriter's fantasy; it was reality, and the culprit was identified as a single-celled organism called Pfiesteria piscicida.
Fish weren't its only targets. Watermen and others who used the rivers for recreation soon began reporting mysterious ailments following fish kills; so did laboratory researchers studying the organism. Those afflicted reported a variety of symptoms, including headaches, skin rashes, eye irritation, respiratory difficulties, gastrointestinal problems, and memory loss.Using sophisticated scanning devices, medical researchers found several cases of brain abnormality in: these patients. Simultaneously, laboratory studies confirmed that Pfiesteria toxin caused neurological problems in rats.
Researchers found that most cases of human illness came after the victims had direct contact with water through activities such as handling fish, taking water samples, or water skiing. But in several instances it appeared the patient's only exposure was simply breathing the air close to a Pf esteria-caused fish kill. This led to the conclusion that Pfiesteria toxins may evaporate and form an aerosol that can cause illness in persons who merely inhale droplets of the stuff. Furthermore, there is evidence it is not even necessary for a fish kill to occur before a potential human health hazard can exist.
These scary findings set off a regional economic crisis, inciting near hysteria in the fishing, seafood, and recreational industries. Business dried up for seafood wholesalers and restaurateurs; charter-boat captains reported widespread cancellations by fearful clients. Were these fears justified? Dr. J. Glenn Morris, M.D., a University of Maryland physician chosen to lead a medical team looking into the problem, said they were probably exaggerated. Morris noted the great majority of fish affected by Pfiesteria have been Atlantic menhaden, a non-edible species. Edible species have been only incidentally represented in fish kills and may not be targeted by the organism, he says.
"Fish with lesions are possible indications of low-intensity outbreaks of P/iesteria," Morris said. However, "there's no reason to worry about eating fish. There is no evidence whatsoever of food-related illness." Moreover, it appears enzymes in the stomachs of edible fish break down Pfiesteria toxin, so if a striped bass or bluefish should eat a Pfiesteria-infected menhaden it would not be affected.
What about the threat to anglers? That, too, may have been overstated. Only in very small areas have fish kills been observed. Officials suggest most fishing areas are safe. Nevertheless, Dr. Morris suggests it's a good idea to "be sensible. If you're fishing and notice a fish kill or fish with lesions, pick up and go some place else." Witnesses to Pfiesteria outbreaks report the water takes on a "chocolatey" appearance and feels hot and peppery to the touch, with dead fish floating on the surface. Common sense dictates that if you notice any of these things, it's time to go elsewhere.
There is further cause for optimism in the fact that it now appears the majority of Ppcsteria-infected victims have made a full recovery after two or three months. Nevertheless, questions still linger about where this vicious organism came from and why it suddenly had such an impact.
Pfiesteria piscicida is a type of single-celled animal called a dinoflagellate. Of many species, only few dozen are known to produce toxins. Among these are the organisms that cause the familiar red tides that plague coastal waterways all over the world, killing marine mammals, birds, and fish.