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. Invasive Species. Te introduction of any invasive species is cause for concern, and the prevalence of warmer water temperatures may increase the likelihood of the invasion of additional exotic species, once thought to be non-threatening because the winters were too cold for their survival. While exotic species invasion is a concern, there is insuf- cient research to understand the efects to this community. Te Asian Clam is found in aquatic systems throughout the state but its efects on native mussels are largely unknown. Flathead Catfsh are a concern because of direct predation on native species. Nutria are considered a serious pest species in the United States because they eat a variety of wetland and agricultural plants and their burrowing damages streambanks, impoundments, and drainage systems. Invasive plants in the riparian area can have negative impacts on stream systems by cre- ating a monoculture (such as Japanese Knotweed) with poor nutrient inputs that reduces bank stability and allows too much sunlight and therefore, creates warmer stream tem- peratures. Exotic insect pests may be a signifcant factor in small river communities because they negatively impact native vegetation, thereby allowing nonnative species to fourish. Climate Impacts. Potential changes in precipitation have numerous and varied efects. Severe and prolonged droughts may decrease stream fow, decrease groundwater recharge, and increase evaporation, resulting in impacts to streams of this theme. A decrease in overall summer precipitation will likely cause reduced water fows, which will contribute to warmer water temperatures and further stress water quality. Tis is particularly import- ant in the context of seasonal droughts because during low-fow periods, nutrients may become concentrated and fush out of systems more slowly (DeWan et al. 2010; Karl et al. 2009; Band and Salvesen 2009; Holman et al. 2010) . Increased air temperatures may lead to increased water temperatures and potentially lower DO levels. Higher air and water temperatures can also lead to increased evaporation, which results in less fowing water available for aquatic species. Hot spells can have the same efect as overall increased air temperatures but on a much more acute scale. Algal blooms are possible in these systems and can exacerbate DO problems, particularly when fows are low (DeWan et al. 2010; Karl et al. 2009; Band and Salvesen 2009; Holman et al. 2010).
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
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2015 NC Wildlife Action Plan
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