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Article Excerpt
ABSTRACT -- The Duck River watershed in middle Tennessee is one of the most biologically diverse river drainages in the United States. Over 500 species of aquatic plants, vertebrates and invertebrates have been documented, many of which are endemic. Several inventories on the mussel and fish fauna of the watershed have been conducted, but little attention has been directed towards herpetofauna. A herpetological inventory was conducted using a variety of field techniques including visual encounter surveys, drift-fence/pitfall traps, aquatic turtle traps, and road cruising. The inventory documented 51 species (26 amphibian and 25 reptile) within the watershed accounting for 68.9% of the 74 potential herpetofaunal species. Between this study and a recent herpetofaunal survey of Arnold Air Force Base in Coffee County, 64 (31 amphibian and 33 reptile) herpetofaunal species were documented accounting for 86.4% of the potentially encountered species in Coffee County.
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Many ecosystems throughout the southeastern United States are rich in species of herpetofauna. Herpetofauna may constitute the greatest vertebrate biomass in many forest ecosystems (Congdon et al., 1986). They are important nodes in ecological food webs (Vitt et al., 1990), and are of potential value as biological indicators of environmental health of habitats (Bury et al., 1995). As such, herpetofauna may act as an early warning sign for other populations of organisms in danger of decline or possible extinction.
In recent years, concerns have increased over amphibian and reptile population declines and extinctions worldwide (Blaustein and Wake, 1990; Richards et al., 1993; Young et al., 2001; Carey and Alexander, 2003). Human-related factors such as habitat fragmentation and destruction (Dodd and Smith, 2003), timber harvesting (Petranka et al., 1993), habitat acidification (Blaustein et al., 2003), environmental contamination such as pesticides, herbicides, and metals (Blaustein et al., 2003; Boone and Bridges, 2003), and the introduction of exotic species that compete or predate on native species (Knapp and Matthews, 2000) have been associated with documented population declines.
The United States Fish and Wildlife Service (USFWS) currently lists 21 species of amphibians and 37 species of reptiles as either endangered or threatened within the United States with an additional 11 species of amphibians and 6 species of reptiles as candidates for federal listing (http://endangered.fws.gov, 2004). At the state level in Tennessee, 1 species of amphibian and 3 species of reptiles are listed as threatened with 10 species of amphibians and 4 species of reptiles deemed in need of management (Tennessee Dept. of Environment and Conservation, Division of Natural Heritage, 2004). As human encroachment continues on already fragmented and degraded areas, these figures are likely to increase.
Few species have been adequately inventoried and monitored over a long period of time (Bury et al., 1995). Consequently, there exists a significant need to inventory and monitor amphibian and reptile populations to better understand the distribution of herpetofaunal declines, their associated factors, and influence on biological and ecological interactions. Inventories provide baseline data needed to develop effective monitoring programs and management strategies for individual species, habitats, and geographic areas.
For this study, a herpetological inventory was conducted for the upper Duck River watershed within Coffee County, Tennessee, to compile a species list for the area. The Duck River is one of the most biologically diverse river systems in the United States with over 500 documented species of aquatic plants, vertebrates and invertebrates including several endemic mussels and fish species. While several surveys have been conducted on the mussel and fish fauna of the watershed (Isom and Yokley, 1968; Jenkinson, 1988; Nieland, 1982; Scott and Gardner, 1995), little attention has been given to herpetofauna.
MATERIALS AND METHODS
Study Area -- The upper portion of the Duck River watershed, beginning at its origin in northern Coffee County, encompasses 1553 sq. miles of land in four counties in south-central Tennessee: Bedford, Coffee, Marshall, and Williamson (Fig. 1). One major impoundment, Normandy Reservoir, is found within the region with a surface area of 3230 acres at full pool. Dammed near the Bedford-Coffee county-line in 1976, the reservoir is located entirely within Coffee County and aids in flood control, water supply, and recreation (Tennessee Valley Authority, 2000). Most of the watershed located within Coffee County lies within the Eastern Highland Rim Physiographic Province; however, land surrounding Normandy Reservoir is part of the Outer Central Basin (Miller, 1974). The Eastern Highland Rim averages 305 m elevation and is characterized by gently rolling...
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