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Importance of Wetlands to Endangered and Tlueatened Species despite protection from human disturbance for almost 30 years (Ogden, 1978). Human alteration of the wetland drainage patterns of south Florida has had a major impact on the status of the species and may severely hamper attempts to reintroduce it into formerly favorable habitat. EXAMPLES FROM COASTAL WETLANDS The Key mud turtle, Kinosternon bauri bauri, and the Cudjoe Key rice rat, Oryzomys argentatus, are south Florida species restricted to fresh water wetlands on the lower keys. A limited amount of habitat is available in the porous limestone of the area which un- fortunately is rapidly being drained and developed•for housing (Spitzer and Lazell, 1978). The fresh water marshes have been drained in an attempt to eliminate the breeding sites of mosquitos. The Key mud turtle does not possess any mechanisms for tolerating salt (Denson, pers. comm.) and loss of marsh could extirpate both the mud turtle and rice rat. Wandering turtles are also killed in large numbers by highway traffic as they go from marsh to marsh. Salt marshes have been known to be extremely productive. Living in some of the marshes on the South Atlantic and Gulf Coasts is a unique assemblage of snakes physio- logically adapted to a saline environment. One species, the Atlantic salt marsh snake, ,Nerodia fasciata taeniata, inhabits the coastal marshes of Volusia, Brevard, and Indian River Counties in Florida. Like the Key mud turtle, the Atlantic salt marsh snake faces the threat of habitat destruction and drainage of habitat in its limited range. Habitat modification, however, has introduced an entirely new threat to the genetic uniqueness of the subspecies, namely hybridisation with closely related subspecies of fresh water snakes. Habitat alteration allows the fresh water species to invade areas to which they were pre- viously not adapted. The two subspecies interbreed and the physiologically distinct salt marsh snake loses its identity as a result of breakdown of ecological isolating mechanisms (Dodd, 1978). EXAMPLES FROM INLAND FRESH WATER WETLANDS Many inland species of endangered and threa f__~,.,.,amphibians and revtiles are dependent on wetlands. e s ackwater darter, Etheostoma boschungi (Wall and Williams, 1974), a small (50-60 mm) colorful fish of northern Alabama and southern Tennessee, inhabits small to moderate sized creeks (up to 12-m wide and 2-m deep), typically with slow current most of the year, but depends on small shallow wetlands for reproduction (Boschung, 1976). During the months of December and January, the darters aggregate and begin their spawning migration. They usually move upstream a distance of 1.6 to 5 km, reaching their wetland spawning habitat in February. The spawning habitat consists of seepage areas in open fields adjacent to the stream. Spawning takes place in shallow water (2 to 8 cm) with eggs deposited exclusively on juncus grass, Juncus acuminates, al- though several other species of sedges and grasses are present. When eggs hatch, larval fish remain in the immediate area for a period of 4 to 6 weeks before moving to the stream. Although small and widely spaced, these wetland habitats are essential`to the continued survival of the slackwater darter. Any barrier which would prevent the darters from reaching their spawning areas or destruction of the wetlands would further reduce the population of the threatened fish. 569