Chapter 4 Habitats
dissolved oxygen depletion and result in local degradation of water quality. Such conditions are temporary and are readily alleviated by increased water flow or increased wind velocity.
In Coastal Plain streams, stratification may occur due to saltwater intrusion occurring as a subsurface density flow. The denser saltwater does not mix with the less dense freshwater and as a result the water column becomes stratified. Oxygen depletion as well as toxic bacterial and algal blooms can be associated with this type of event, often leading to significant mortalities within the aquatic community. Invasive Species. Warmwater streams provide pathways for invasion by nonnative species. In the absence of obstructions such as dams, culverts, and waterfalls, invasive species can travel long distances within a system and establish viable populations within the main stem river as well as tributaries. Once in a river system invasive species are difficult, if not impossible, to eradicate or even control. Water Quality. Warmwater streams typically occur at lower altitudes with a relatively moderate topography. Thus, the adjacent land is more likely to be used for purposes such as residential development, industry, commerce and agriculture. All of these are sources for discharges of various chemicals into the river, which can moderately or substantially affect biological communities. The moderate temperature regime of these waters often accelerates biological activity promoted by inputs of organic compounds resulting in degraded water quality. Sedimentation is particularly problematic in warmwater streams. Development of riparian and adjacent areas can accelerate erosion and relatively low stream gradients can promote the deposition of eroded sediment within the stream channels. Sedimentation can decrease the depth, increase water temperatures and decrease the biological productivity of affected waters. Rivers flowing through or near urban and suburban areas may receive incompletely processed pharmaceuticals from sewage treatment plants that can affect the production of hormones in aquatic fauna. 4.2.5.4 Climate Change Compared to Other Threats Comparing climate change to other ecosystem threats can help define short- and long-term conservation actions and recommendations. Aquatic systems have been under threat from a variety of perturbations in the past and many of those continue today. Conversion of land, both from forest to agriculture or silviculture, as well as from development projects, continues to threaten stream integrity resulting in increased sediment, bank erosion, and stormwater runoff containing sediment and other potentially toxic materials. Considering current conditions in these systems, climate change is likely to have a synergistic effect with other threats that are of more immediate concern.
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2025 NC Wildlife Action Plan
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