4.2 Aquatic Communities
4.2 Aquatic Communities Te various geology, physiography, and climate attributes of North Carolina contribute to the wide diversity of aquatic resources found across the state’s ecoregions (Abell et al. 2000; Smock et al. 2005) . North Carolina’s natural aquatic communities provide a variety of potential habitats that are infuenced by numerous conditions such as landscape position, gradient, width, depth, temperature, velocity, substrate or bed material, chemistry, and land cover (Winger 1981) . Te aquatic communities can be thought of as a mosaic of temporal and spatial conditions spread across the continuous reach of the system (Vannote et al. 1980) . While aquatic systems represent a small percentage of the landscape, they are living sys- tems that represent some of the most endangered ecosystems in the state because they are subject to an increasing number of persistent threats that include resource withdrawals, pollution, invasive species, barriers, the efects of climate variability, and impacts to the surrounding terrestrial communities (MEA 2005; Revenga et al. 2005; Abell et al. 2000, 2008) . Tere are many subject areas in science and biology where classifcation systems have been developed and accepted for standard practice, and are commonly used as descriptions and for locating, storing, and exchanging data. While there is not one globally agreed upon classifcation system applied to describing aquatic communities or hydrologic systems, there are several defnitions and classifcation schemes in wide use. For example, water- sheds (also called basins or catchments) (Torp 2002; Wagener et al. 2007) are commonly described and delineated to include all of the land draining into a particular surface water system such as a stream, river, or lake (Abell et al. 2000) . A watershed can represent an unlimited number of spatial scales such as the area that drains to a single headwater stream or a larger area that encompasses several streams that share a hydrologic connection. Te largest watersheds delineated in North Carolina rep- resent all of the land draining into one of the 17 major river systems in the state which are identifed in Table 4.1.2 and described in Section 4.5 of this chapter. Inland freshwaters are a type of aquatic natural community generally categorized as being either lotic or lentic systems. Lotic systems are running waters such as rivers and streams (Alexander and Fairbridge 1999; Abell et al . 2000; Torp and Covich 2001) and there are various methods used to classify them based on pattern, geomorphological conditions, or by groups using shared characteristics (Rosgen 1994) . An early method categorizes streams based on connec- tivity patterns with other fowing systems, and classifes streams into a dendritic hierarchi- cal order where the smallest unit is a frst order stream (Strahler 1957) . Lentic systems are standing waters such as lakes, reservoirs, ponds, swamps, and marshes. Schindler and Scheuerell (2002) note that lakes are complex ecosystems with distinct habi- tats that are infuenced by physical parameters (e.g., depth, substrates), thermal infuences
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2015 NC Wildlife Action Plan
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