4.2 Aquatic Communities
Comparison of climate change with other threats to large creeks/small rivers
T ABLE 4.9
Rank Order Comments
Threat
Development
1 Development causes direct, secondary, and cumulative efects. Residential development can increase erosion during the construction process and as a secondary result of increased impervious surfaces in the watershed. Growth and development increase water supply demands, and streamfow patterns are being altered due to rapid urbanization. An increase in impervious sur- faces due to roads, parking lots, homes, and businesses also increases the amount and speed of runof being delivered into aquatic systems. Decreased groundwater recharge between storms due to impervious surfaces contributes to reductions in stream basefow. 2 Erosion and the resultant sedimentation are the largest sources of nonpoint source pollution in most aquatic systems. Runof from urban areas often con- tains higher concentrations of nutrients (such as nitrogen and phosphorus), sediment, metals, hydrocarbons, and microbes. Point and nonpoint sources— runof and EDCs—are also threats. 2 Irrigation and water supply withdrawals pose a threat to fow regime.
Pollution
Water Withdrawals Flood Regime Alteration
2
High and low fow extremes pose a threat.
Livestock
3 Livestock access to streams contributes heavily to bank erosion, sedimenta- tion, and nutrient input. 3 Clearing of riparian areas is problematic. Timber harvesting can increaseero- sion if proper controls are not used and maintained, in addition to damage caused by poorly constructed and maintained timber roads. 3 Loss of riparian vegetation contributes to streambank erosion and sedimenta- tion. Riparian vegetation serves as a food/nutrient input to the stream com- munity and helps regulate stream temperature by providing shade. 4 Climate change-related challenges to water quality and quantity are similar to those being caused bygrowth and development. Climate change efects will likely amplify other threats and increase their severity in aquatic systems. 4 Loss of forest cover can increase erosion and sedimentation, as well as nega- tively impact aquatic systems. 5 Invasive plants in the riparian area can have negative impacts on stream sys- tems by creating a monoculture with poor nutrient inputs that reduces bank stability, thereby allowing too much sunlight and warmer stream tempera- tures. Invasive aquatic species, like the Asian Clam, may have negative efects on native species due to competition for space and resources. Specifc interac- tions are unknown. 6 Water supply needs could increase number of impoundments and their dis- ruptions to fow regime and aquatic habitat.
Logging/ Exploitation
Lack of Riparian Vegetation
Climate Change
Conversion to Agriculture/ Silviculture Invasive Species
Impoundments
Small river communities provide a number of important habitats, life cycles, or prey com- ponents to a vast assemblage of terrestrial, semi-aquatic, and aquatic wildlife. Wetlands associated with riverine systems can be important breeding sites for some amphibian and
262
2015 NC Wildlife Action Plan
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