4.2 Aquatic Communities
Many species associated with lakes and aquatic habitats rely on shoreline vegetation for shelter, foraging, breeding, and nesting. Shrubs and trees growing around shorelines pro- vide important nesting, roosting, and feeding sites for birds, especially colonial waterbirds such as herons. Development of lake shores causes loss and fragmentation of this ripar- ian habitat. In many cases, reservoirs and impoundments are subject to management for recreational activities such as boating and fshing. Excessive human use of lake shores can lead to increased trampling and erosion of the banks. Human intrusion can disrupt natural behaviors of animals using this habitat. Water Quality. Pollution can cause problems for many aquatic organisms and their preda- tors. Heavy metals can be a particular concern because they can bioaccumulate in animal tissues. Smaller water bodies near agricultural or residential areas can sufer from excess nutrient run-of, leading to algal blooms and low DO levels. Contaminants can be carried by sediment that washes into surface waters. Changes in hydrology and water chemistry can impact water quality negatively. Nonpoint source pollution and the efects of dams and impoundments pose historic and current threats to freshwater mollusks (Bogan 1993; Neves et al. 1997; Richter et al. 1997 ). Impacts from hydro- power development in large river basins have altered and degraded a substantial portion of habitat for most native aquatic species, primarily in large streams and rivers. Irregular fooding during the growing and nesting seasons can afect the reproductive success and survival of species that depend on this habitat type. Te mainstem Hiwassee and Nottely rivers, for example, are signifcantly altered by direct and indirect impacts from impoundment. Fifty-seven miles of historically free-fowing riverine habitats are now either seasonally or permanently fooded by Chatuge, Mission, Hiwassee, and Appalachia reservoirs or are afected indirectly by impoundment. Te unimpounded reaches of the Nottely and Hiwassee rivers are afected by cold water, altered hydrologic regimes, and periodic low levels of DO due to hypolimnetic discharges and peaking power production releases from Chatuge and Nottely dams. Impoundment and thermal alteration may further afect native species by fragmenting suitable habitat and isolating historically contiguous populations in tributaries. Invasive Species . Reservoirs can be a barrier to upstream movement of invasive species, but more often they act as stepping-stones for the dispersal of exotic and nonnative species across landscapes. Exotics are species that are not native to the United States, and species that are not native to North Carolina, but that may be native to other areas of the United States, are considered nonnatives. Havel and colleagues (2005) conducted a study called “Do Reservoirs Facilitate Invasions into Landscapes?” that examines how reservoirs might facil- itate the spread of invasives across landscapes. Populations often become invasive because there are no natural predators or conditions to control growth. A variety of passively
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2015 NC Wildlife Action Plan
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