4.2 Aquatic Communities
T AB LE 4.12 Comparison of climate change with other threats to stream swamp systems
Rank Order Comments
Threat
Development
1 Direct, secondary, and cumulative efects from development include increased sediment, bank erosion, and stormwater runof containing sedi- ment and other potentially toxic materials. 2 During droughts, water levels will decline as temperature increases and rainfall events decrease. Any increase to pumping or water withdrawals can cause depletion and low DO due to low-fow conditions. 2 While bank vegetation is usually undisturbed, logging is a major threat to streams in the Coastal Plain. Loss of forest cover can cause increased ero- sion and sedimentation and negatively impact aquatic systems. 2 Irrigation, water supply, and energy development withdrawals pose a threat to fow regime. 2 Sea level rise, as a result of climate change, is a major threat to Coastal Plain rivers. 3 Point and nonpoint sources—runof and EDCs—are threats. Erosion and the resultant sedimentation are the largest sources of nonpoint source pollution in most all aquatic systems. Runof from urban areas often contains higher concentrations of nutrients, such as nitrogen and phosphorus, sediment, metals, hydrocarbons, and microbes. 3 Loss of riparian vegetation contributes to stream bank erosion and sedi- mentation. Riparian vegetation serves as a food/nutrient input to the stream community and helps regulate stream temperature by providing shade. 4 Livestock access to streams contributes heavily to bank destabilization and erosion, sedimentation, and nutrient input. 4 Invasive plants and animals are potential problems, although specifc inter- actions are unknown.
Groundwater Depletion
Logging/ Exploitation
Water Withdrawals
Climate Change
Pollution
Lack of Riparian Vegetation
Livestock
Invasive Species
Aquatic species could experience shifts in their range or distribution and sensitive species may experience decline or extirpation due to changes in water quality and habitat. Te ability of freshwater organisms to move to new locations is constrained by the connectivity of streams and rivers within drainage basins and by the connectivity between suitable hab- itat types within an aquatic system. Saltwater intrusion is expected to impact large rivers initially, and the extent to which saltwater will reach small streams and swamps is yet to be determined. However, if these smaller systems experience saltwater intrusion, existing freshwater fauna may be replaced with more brackish water species and, if salinity levels increase gradually, there could be adaptation by some freshwater species to this change. Additionally, if these systems remain freshwater, but large rivers at confuences with these smaller systems are brackish water, it could lower genetic diversity and available habitat for species that moved between large and small river systems in the Coastal Plain. Also, there may be a change in the number of
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2015 NC Wildlife Action Plan
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