4.2 Aquatic Communities
T AB LE 4.8 Comparison of climate change with other threats to headwater streams/ small creeks
Rank Order Comments
Threat
Development
1 An increase in impervious surfaces due to roads, parking lots, homes, and businesses, increases the amount and speed of runof being deliv- ered into aquatic systems, and decreased groundwater recharge between storms leads to a decrease in stream basefow. Runof from urban areas often contains higher concentrations of nutrients (such as nitrogen and phosphorus), sediment, metals, hydrocarbons, and microbes. 1 Streams in the Triassic Basin are particularly susceptible to erosion and are likely at greatest risk from erosion given proximity to many urban and suburban development centers. Erosion and the resultant sedimenta- tion are the largest sources of nonpoint source pollution in most aquatic systems.
Erosion and Sedimentation
Climate Change
2
Headwater streams may shrink in habitat or extent.
Lack of Riparian Vegetation
2 Lack of riparian vegetation or inadequate width of forested bufer can cause streambank erosion and sedimentation. In addition to stabilizing streambanks, riparian vegetation serves as a food/nutrient input to the stream community and helps regulate stream temperature by providing shade. 2 While bank vegetation is usually undisturbed, logging is a major threat to streams if proper erosion controls are not used and maintained. Poorly constructed and maintained timber roads also contribute to erosion.
Logging/Exploitation
Flood Regime Alteration
3
High and low fow extremes pose a threat.
Invasive Species
4 Invasive plants in the riparian area often have negative impacts on stream systems by creating a monoculture with poor nutrient inputs, reducing bank stability, and allowing too much sunlight to infltrate, causing warmer stream temperatures. Invasive aquatic species, like the Asian Clam, may have negative efects on native species, such as when competing for space and resources. 4 Livestock access to streams contributes heavily to bank erosion, sedimen- tation, and nutrient input. 5 Te majority of headwater streams are on lands in private owner- ship, making them at risk from land use practices that may increase stormwater runof of nutrients, sediment, and contaminants. Endocrine-disrupting chemicals in treated wastewater can inhibit reproduction and cause feminization of mussels and fsh (Conn et al. 2006; Kim et al. 2007; Kasprzyk-Hordern et al. 2008; Joss et al. 2006; Kolpin et al. 2002; Nowotny et al. 2007) . Runof from impervious surfaces carries lawn pes- ticides, road oil, and other pollutants from developed areas into surface waters.
Cattle in Streams
Pollution
255
2015 NC Wildlife Action Plan
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