"Under federal law, you can build a parking lot right up to the edge of the wetland"
AIKEN, S.C. -- Federally delineated wetland boundaries and most state regulations do not protect the upland habitats surrounding wetlands, areas that are critical to the life cycles of freshwater turtles and other semiaquatic animals, according to the lead article published this month in the scientific journal Conservation Biology.
Freshwater turtles nest and hibernat on land up to 900 feet from the edge of the wetland in a study conducted at a Carolina bay on the U.S. Department of Energy's 310-square-mile Savannah River Site near Aiken, S.C.
The findings also indicate that federal regulations protected none of the nesting and hibernation sites of three turtle species, and even the most stringent state regulations -- those of Massachusetts -- protected only 44 percent of the animals' sites, according to researchers Drs. Vincent Burke and Whit Gibbons of the Savannah River Ecology Laboratory.
"Currently, under federal law, you can build a parking lot right up to the edge of the wetland," said Dr. Burke. "Obviously, federal regulations are not protecting these animals. Several states have recognized this problem and created buffer zones around wetlands, but even these are not large enough to protect all of the animals.
"If we don't protect the habitats around wetlands that are necessary for these animals to complete their life cycles, those populations will eventually go extinct," Dr. Burke said. "The types of habitat alterations from development usually make the habitat incompatible with the animals completing their life cycles. Most nesting areas are not manicured lawns."
Findings are important because of upcoming debate in Congress
researchers point out they are not necessarily saying there should be no development within the 900-foot buffer zone they believe is needed. The upland habitats surrounding their study area, Ellenton Bay, contain small research facilities, two experimental plots, two lightly traveled paved roads and several seldom-used unpaved roads. Yet Ellenton Bay has maintained a diverse turtle community for more than 25 years, according to Dr. Gibbons' research.
"If it is a priority to protect the semiaquatic animals that inhabit wetlands, we need to restrict alterations of terrestrial habitat to low impact developments and keep them as far away from the wetland as possible," Dr. Burke said. "It doesn't necessarily mean people can't live near wetland habitats, just that the development needs to be monitored and restricted."
The researchers' findings are timely as Congress is soon expected to debate proposed revisions that, according to Dr. Gibbons, "would weaken the Clean Water Act, which currently offers some protection for wetlands." Last summer, the House passed revisions that would eliminate protection for many wetlands because of requirements that wetlands have surface water on 21 consecutive days during the growing season, Dr. Gibbons said. Key senators have expressed opposition to this proposal, and President Clinton has said he will veto it if it gets to his desk.
Current law protects wetlands of greater than one acre that contain hydric soils, wetland hydrology and wetland vegetation. In general, federal regulations protect wetland habitats that are regularly inundated or saturated by water. Many states have adopted stronger wetland protection laws, including buffer zone measures that protect habitats within 100 feet of a wetland.
Drs. Burke and Gibbons' study was intended to measure the effectiveness of wetland protection laws in meeting the primary goals of federal and state regulations. Those goals are:
The researchers used aerial photography combined with geographic information system analyses to evaluate the protection offered by federal law and the most stringent state law. They chose freshwater turtles as sentinel species to represent the variety of semiaquatic organisms that require both wetland and upland habitats to complete their life cycles. Their study examined habitat use by mud turtles, Florida cooters and slider turtles, which they monitored with radio telemetry.
Data for the three species indicated that nesting and hibernation took place in the terrestrial habitats up to 900 feet from the edge of Ellenton Bay. Eliminating the 10 percent of nest and hibernation sites furthest from the edge of the bay indicated the need for a buffer zone that extends 250 feet from the wetland's edge.
"The size of buffer zones required to maintain the integrity of populations of semiaquatic fauna undoubtedly varies according to wetland type, upland characteristics, geographic region and resident species," the researchers wrote. "However, methodologies that reasonably determine the buffer zone sizes needed for different wetland classes are entirely feasible."
For example, the researchers cite a study of the Little and Big Econ rivers in Central Florida. The study suggests that river and river floodplain integrity could be maintained with an 1,100-foot buffer zone. In the absence of additional information on other similar habitats in the Southeast, officials could assume that an 1,100-foot buffer zone would adequately protect adjacent terrestrial habitats, the researchers said.
"We recognize that our ideas will benefit from refinement," Dr. Burke said of the Conservation Biology article. "We just want people to have the wetland in mind before they develop land next to it."
Drs. Burke and Gibbons encourage the establishment of large, regulated buffer zones around wetlands if preservation of the animals in wetlands is a priority, they said.
The researchers' bottom line is the importance of the interconnection between terrestrial and aquatic habitats in maintaining wetland viability, they said.
"To preserve the biodiversity associated with wetlands, we will need to recognize the importance of such interconnections and consider the wetland habitat as the core of a larger landscape," the researchers wrote. "To be successful, such a conservation effort will almost certainly require legislation that mandates large, sometimes economically disadvantageous, buffer zones around wetlands."
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