Chapter 4 Habitats
Water classification data are available from the National Hydrography Dataset (NHD), a database that interconnects and uniquely identifies the millions of stream segments or reaches that comprise the surface water drainage systems in the United States. The NHD provides a national framework that allows information to be linked by stream reach address to an organization thereby allowing water quality data to be shared with other organizations, analyzed using a Geographic Information System (GIS), and easily integrated into many different types of applications to the benefit of all (USEPA 2025a) . 4.5.2 Aquatic Biodiversity and Imperilment The Southeast region has the highest aquatic species diversity in the entire United States (Burr and Mayden 1992, Taylor et al. 1996, Warren et al. 2000;, Williams et al. 1993) . Southeastern fishes make up two- thirds of United States fauna, and nearly half of the North American fish fauna (Burr and Mayden 1992) . Molluscan diversity in the region is globally unparalleled, with 91% of all United States mussel species found in the Southeast (Neves et al. 1997) . Crayfish diversity and global importance in the region rivals that of mollusks (Taylor et al. 1996) , and crayfish in the Southeast comprise 95% of the total species found in all of North America (Butler 2002a) . North Carolina freshwaters support a significant proportion of that diversity with at least 210 freshwater fish, 125 mollusk, and 45 crayfish species native to the state. Unfortunately, patterns of imperilment for aquatic species are similar amongst taxonomic groups. Collen et al. (2014) report almost one in three freshwater species is threatened with extinction worldwide which, in comparison, is proportionally greater than the risk of extinction for terrestrial species (Burkhead 2012) . More than two-thirds of the nation’s freshwater mussel and crayfish species are extinct, imperiled, or vulnerable (Williams et al. 1993, Neves et al. 1997, Master et al. 1998) . The majority of these at-risk species are native to the Southeast. • North Carolina ranks third among southeastern states in number and percentage of imperiled fishes (Warren et al. 1997) . • Freshwater mollusks are suffering even greater declines, with numerous mussel and aquatic snail species that formerly occurred in the Southeast now presumed extinct (Neves et al. 1997) . • Among crustaceans listed as endangered or threatened in the United States, more than half are from the Southeast (Schuster 1997) . • Twelve species of North Carolina crayfish are listed as species of concern or rare in the state, with their small native range the primary factor in their vulnerability to habitat loss and competition (Clamp et al. 1999, Taylor et al. 1996) . Threats specific to crayfish include pollution and impoundment, but competition with nonindigenous species is also a primary threat to many species (Taylor et al. 1996) . National and regional causes of declines among all aquatic taxa are widely attributed to habitat destruction and degradation and the introduction of nonnative species (Williams et al. 1993; Taylor et al. 1996; Etnier 1997; Warren et al. 1997; Collen et al. 2014) . The medium-sized rivers and creeks that provide important habitat for many aquatic species are frequently impounded and substrates have
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2025 NC Wildlife Action Plan
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