Chapter 4 Habitats
4.2.5 Warmwater Aquatic Communities 4.2.5.1 Ecosystem Description
The warmwater designation is based upon two general principles: temperature regime and fish community composition. Temperature regime can be used to classify warmwater streams where summer temperatures are predominantly warmer than 25°C (77°F). This is based on suggested temperatures that define cold and coolwaters (USACE 2003) . Warmwater streams can have a wide variety of fish species composition depending on landscape location, surrounding land use, elevation, substrate, depth, temperature gradients, and water quality. Examples of warmwater fish species in North Carolina include Blacknose Dace, Creek Chub, Pumpkinseed, Largemouth Bass, and White Sucker. 4.2.5.2 Location of Habitat Warmwater streams are found throughout the state. Cold and coolwater streams and rivers that originate in the upper portion of watersheds in the Mountains, transition to warm waters with a decrease in elevation and as tributary waters combine to form larger systems. Examples include the lower reaches of the Broad River and Catawba River. 4.2.5.3 Problems Affecting Habitats Chapter 5 Threats provides more information about 11 categories of threats most likely to impact North Carolina’s wildlife and natural communities. The list of threats is based on definitions and classifications published by Salafsky et al. (2008, 2024) . The following information focuses on current and anticipated threats for this habitat. Dams . Impacts to aquatic species occur when habitats are modified and movement between habitats are blocked (Lessard and Hayes 2003) . Dams change the overall physical, chemical, and biological structure of streams by modifying stream flows and changing lotic systems to lentic systems; influencing the export of water, sediment, and nutrients to downstream systems; altering water temperatures and thermal regimes; and disconnecting streams from their floodplains and riparian communities (Wang et al. 2011) . The results of a study by Wang et al. (2011) indicate that both downstream and upstream dams influence fish assemblages in non- impounded stream segments; however, the study found the cumulative effects of other environmental factors such as stream size, adjacent land uses, water quality, and stream flow and thermal regimes may have a more significant influence on fish occurrence and abundance. Thermal Stratification and Algal Blooms . Stratification is common during periods of low flow, mid- to-late summer on big rivers and results in hypoxic or anoxic conditions. Thermal stratification is rare in warmwater streams in the Mountains and Piedmont due to the mixing effect of flows and lack of sufficient depth. During periods of low water flow and little wind, deeper pools within a river may become stratified with little or no vertical mixing. Under these conditions, dissolved oxygen levels in the deeper water may be depressed and become unsuitable for many aquatic organisms. Algal blooms in the surface water can exacerbate
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2025 NC Wildlife Action Plan
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