Chapter 4 Habitats
Water Quality. As with coldwater streams, erosion and the resultant sedimentation are the largest sources of nonpoint source pollution in this system. Sources of erosion include disturbance from development activities and agriculture. Residential development, particularly in steep-slope areas, is of particular concern because of increased erosion. Livestock access to streams contributes heavily to bank erosion, sedimentation, and nutrient input. Timber harvests and poorly constructed and maintained timber roads are additional sources of erosion if proper controls are not used and maintained. Many of the water quality and water quantity impacts resulting from climate change are analogous to impacts from economic development and population growth in North Carolina. Climate change is predicted to decrease rainfall and therefore limit water supply; however, growth and development have increased and continue to increase water supply demands. Historical stream flow patterns are projected to be altered due to climate change impacts, but these are already being altered due to rapid urbanization. An increase in impervious surfaces due to roads, parking lots, homes, and businesses, increases the amount and speed of runoff being delivered into aquatic systems. Decreased groundwater recharge between storms due to impervious surfaces leads to a decrease in stream base flows. Runoff from urban areas often contains higher concentrations of nutrients (such as nitrogen and phosphorus), sediment, metals, hydrocarbons, and microbes. Coolwater systems may be more likely to experience a change in species composition as aquatic species shift their range or distribution, and sensitive species decline or are extirpated by changes in water quality and temperature. Aquatic species are particularly sensitive to temperature cues, and warming waters could cause species in coolwater habitats to attempt moving upstream into previously cold waters if there is suitable habitat. Some mussel species, for example, are limited in distribution because of coldwater influences. Alternatively, species could become extirpated because they are unable to move before their current locations persistently become warmwaters. Invasive Species. Introduction of nonnative species creates competitive pressure on native populations. Yellowfin Shiner, native to the Savannah River Basin, has been introduced to the Little Tennessee River Basin. Its range could expand into other coldwater systems with warming water temperatures. Changes in stream conditions could increase competition with fish species, particularly the federally threatened Spotfin Chub. Climate Impacts. Research conducted by Eaton and Sheller (1996) and Mohseni et al. (2003) assessed the effects of climate warming on 57 species of fishes in streams across the United States. Depending on minimum temperature tolerance assumptions, species requiring coolwater habitats could experience a 12% to 15% decrease in available habitat (DeWan et al. 2010) . When the connectivity between streams and rivers within drainage basins provide adequate dispersal corridors, species at the southern extent of their geographical distribution may shift their distributions northward into cooler habitats (Allan et al. 2005) . Where adequate dispersal corridors are
4 - 32
2025 NC Wildlife Action Plan
Made with FlippingBook Ebook Creator