4.2 Aquatic Communities
possible, potentially leading to algal blooms and low DO events. Disturbance by boats and personal watercraft creates wakes and associated noise pollution that disturb water birds and water fowl. High water levels can create shoreline damage (e.g., erosion, fooding) while prolonged low water levels may contribute to water quality issues and impact delivery of lake ecosystem services (Foulds 1977; Wildman et al. 2011; Crase et al. 2008; Molinos et al. 2015) . Surface waters, including natural lakes, often receive wastes, sediments, and pollutants from runof because of their position in the landscape (Dudgeon et al. 2006) . Changes in hydrology and water chemistry afect water quality. Water levels may be low during droughts and periods of high temperatures and lakes may become stratifed with little or no vertical mixing within the water column. Under these conditions DO levels in deeper waters may be depressed and become unsuitable for many aquatic organisms. Algal blooms in the surface water can exacerbate DO depletion and result in local degradation of water quality. Such conditions are temporary and are usually alleviated by increased water fow or increased wind velocity. Water level fuctuations may also lead to changes in patterns of boundary mixing (i.e., the process of enhanced mixing near the lateral boundaries of a lake which afects sediment resuspension and vertical nutrient fuxes), induced mainly in stratifed lakes by internal wave activity at the depth of the thermocline. Progressively declining water levels would be expected to lower the thermocline and therefore displace boundary mixing (Zohary and Ostrovsky 2011; Molinos et al. 2015) . Persistance of these issues can exacerbate water quality prob- lems by contributing to long-term eutrophication in natural lakes (Hambright et al. 2004; Molinos et al. 2015) . 4.2.12.4 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, synergistic efects combined with other existing conditions could stress these sys- tems to the point where several species are unable to persist. Te most important efect of climate change for lakes is likely to be the occurrence of more extreme rainfall events and more frequent droughts. Table 4.13 compares climate change with other existing threats.
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2015 NC Wildlife Action Plan
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