Chapter 4 Habitats
and downstream populations, and evidence suggests that this phenomenon is geographically and taxonomically widespread in eastern North America. These results suggest that some small impoundments enhance conditions for freshwater mussel growth, and some older dams may warrant protection or restoration if downstream reaches support imperiled mussel populations (Singer and Gangloff 2011) . Thermal stratification of impoundments occurs mostly during the warmer seasons, when direct solar radiation and increased air temperatures heat surface layers faster than deeper layers (Sherman 2000; Sherman et al. 2007) , resulting in the formation of a lighter, warmer surface layer of water (epilimnion) and a cold bottom layer (hypolimnion) (Smith and Smith 1998) . Many impoundments have fixed-level off-takes that are situated below the thermocline, hence releasing waters from the colder hypolimnion, which causes downstream coldwater pollution (Sherman 2000; Preece and Jones 2002; Marshall et al. 2006) . The biological impacts of coldwater pollution on warmwater fishes have been documented in a number of studies (Clarkson and Childs 2000; Todd et al.et al.2005; Sherman et al. 2007; Olden and Naiman 2010) and include impeded spawning, lower survival rates, retarded growth rates, and displacement of native species (Martinez et al.1994; Clarkson and Childs 2000; Todd et al. 2005; Sherman et al 2007; Miles and West 2011) . Invasive Species. Introduction of species native to the state into areas where they normally would not occur creates competitive pressure on the native local populations. For example, the Piedmont Shiner, native to the Broad River, and Yellowfin Shiner, native to the Savannah River Basin, have been introduced to the Little Tennessee River Basin where they compete with native species for food, spawning, and cover resources. Their range could expand into other coldwater systems with warming water temperatures associated with discharges or changes to riparian buffers. 4.2.13.6 Recommendations Section 4.2.2 provides recommendations appropriate for all aquatic communities, statewide. Recommendations specific to the river basins that contain reservoirs and impoundments are provided in Section 4.5. 4.2.13.6.1 Surveys Surveys are systematic and scientific methods of collecting information about the distribution, abundance, and ecology of wildlife or their habitats in a specific area at a specific time. A habitat survey is a method of gathering information about the ecology of a site. The results of a habitat survey provide basic ecological information that can be used for biodiversity conservation, planning and/or management, including targeting of more detailed botanical or zoological investigations (Smith et al. 2011) . Repeated surveys using the same methods can provide information about conditions and changes to species assemblages and habitat composition over time. Priorities for conducting distributional and status surveys need to focus on species believed to be declining or mainly dependent on at-risk or sensitive communities.
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2025 NC Wildlife Action Plan
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