4.2 Aquatic Communities
An increase in impervious surfaces due to roads, parking lots, homes, and businesses, increases the amount and speed of runof being delivered into aquatic systems. Decreased groundwater recharge between storms due to impervious surfaces leads to a decrease in stream base fows. Runof from urban areas often contains higher concentrations of nutri- ents (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 extir- pated by changes in water quality and temperature. Aquatic species are particularly sen- sitive 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 infuences. 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. Yellowfn Shiner, native to the Savannah River Basin, has been introduced to the Little Tennessee River Basin. Teir range could expand into other coldwater systems with warming water temperatures. Changes in stream conditions could increase competi- tion with fsh species, particularly the federally threatened Spotfn Chub. Climate Impacts. Research conducted by Eaton and Sheller (1996) and Mohseni et al. (2003) assessed the efects of climate warming on 57 species of fshes in streams across the US. Depending on minimum temperature tolerance assumptions, species requiring coolwater habitats could experience a 12%–15% decrease in available habitat (DeWan et al. 2010) . When the connectivity between streams and rivers within drainage basins provide adequate dis- persal 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 limited or restricted, access to or availability of cooler water habitats may limit the range of those species subject to narrow temperature tolerance (DeWan et al. 2010) . 4.2.4.4 Climate Change Compared to Other Threats Comparing climate change to other ecosystem threats can help defne short- and long-term conservation actions and recommendations. Aquatic systems have been under threat from a variety of perturbations in the past and many of those continue today. Conversion of land (both from forest to agriculture or silviculture, as well as from development projects), continues to threaten stream integrity resulting in increased sediment, bank erosion, and stormwater runof containing sediment and other potentially toxic materials. Considering current conditions in these systems, climate change is likely to have a synergistic efect with other threats that are of more immediate concern. Table 4.7 provides a review of
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2015 NC Wildlife Action Plan
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