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. Runof from urban areas often contains higher concentrations of nutrients (such as nitrogen and phosphorus), sediment, metals, hydrocarbons, and microbes. Decreased groundwater recharge between storms due to impervious surfaces leads to a decrease in stream base fows. Invasive Species. Introduction of nonnative species creates competitive pressure on native populations. Yellowfn Shiner is native to the Savannah River Basin but has been intro- duced to the Little Tennessee River Basin, and their range could expand into other coldwa- ter systems with warming water temperatures. Climate Impacts. Lower water levels during dry times will increase stress to the system. Connectivity to contributing waters within the system will be restricted or eliminated by low- and no-fow conditions. Changes in fow regime will likely result in changes in the overall stream morphology and transport of sediment. An increase in frequency and intensity of storms due to climate change will have a simi- lar impact on stream systems by increasing pollutant loading. Increased storm intensity that causes fooding can lead to increased stormwater runof and erosion. With increased stormwater runof, there is an increase in loading of sediments, nutrients, and contami- nants into streams and potential negative efects on biota, such as fsh kills. With a change in intensity and variability of rainfall, there are potential changes to stream fow patterns, channel hydrodynamics, and the volume of groundwater (Band and Salvesen 2009; Holman et al. 2010; Bakke 2009) . 4.2.3.4 Climate Change Compared to Other Threats Comparing climate change to other ecosystem threats can help defne short- and long-term conservation actions and recommendations. While climate change is not the most severe threat to coldwater systems, a combination of synergistic efects with development and lack of forested riparian corridors could stress these systems to the point where several species are unable to persist. Table 4.6 provides the results of a vulnerability assessment completed by the NCNHP (2010) for coldwater systems that compare climate change impacts in order of importance with other types of potential threats.
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2015 NC Wildlife Action Plan
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