4.2 Aquatic Communities
of riparian bufers. Te North Carolina Ecosystem Response to Climate Change: NC Department of Environment and Natural Resources (NCDENR) Assessment of Efects and Adaptation Measures (NCNHP 2010) Report for Headwater Systems provides more information about the expected impacts of climate change and other threats to this community type. Land Use. Headwater streams are primarily located on private lands and are more likely to be threatened by changes in land use practices. Land use change that results in greater areas of impervious surface can increase stormwater runof of nutrients, sediment, and contaminants. Te increased loads could afect water quality and habitat for aquatic spe- cies (Band and Salvesen 2009) . Headwater systems in agricultural areas where BMPs, such as no-till farming, are used and where riparian bufers are maintained were found to have high macroinvertebrate richness compared to headwaters in urban areas (Moore and Palmer 2005) . Small impoundments used for irrigation or as an amenity (e.g., swimming, fshing) are often located in headwater streams and may not be subject to dam safety rules that carry minimum fow requirements. Lack of minimum fows will exacerbate the efects of drought and where water levels become shallow the resulting high water temperature will kill aquatic species. Riparian vegetation is critical to the overall stream and streambank stability. Lack of ripar- ian vegetation or inadequate width of forested bufer can cause streambank erosion and sedimentation. In addition to stabilizing streambanks, riparian vegetation serves as a food and nutrient input to the stream community and helps regulate stream temperature by providing shade. Water Quality. Headwater streams often make up as much as 85% of the total stream length within a drainage network and contribute both water, woody debris, and nutrients collected from adjacent landscapes downstream to larger streams (Peterson et al. 2001) . Studies have shown that headwater streams retain and transform as much as 50% or more of the nitrogen inputs from their watershed, often within short distances and over short time periods (Peterson et al. 2001) . Despite their small size, headwater streams serve an important function in regulating nitrogen uptake and processing that protects water quality. Small drainages, and especially headwater systems, are sensitive to local conditions such as nutrient loads in runof (Peterson et al. 2001; Meyer et al. 2007) . When nutrient loads are high, head- water streams can lose their capacity to retain and transform nitrogen locally, thereby allowing greater nutrient loads to fow into downstream waters where they contribute to water degradation and eutrophication (Peterson et al. 2001) . Erosion and the resultant sedimentation are the largest sources of nonpoint source pollu- tion in most aquatic systems. Sources of erosion include disturbance from development activities and agriculture. Residential development can increase erosion during the con- struction process, but can also be a secondary cause of increased impervious surfaces in
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2015 NC Wildlife Action Plan
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