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Environmental Sciences Section |
| Biological Assessment Unit | ||||||||||||||||||||||||||||||||||||||||
LINKS DWQ Biological Reference Sites Benthos Fish Tissue SOP Fish Community NCIBI Scores and Ratings
Other Links American
Fisheries Society |
The Biological Assessment Unit is charged with evaluating the water quality of streams and rivers using the biological communities that live there. The group is divided into two areas of expertise: fisheries, and benthic macroinvertebrates or benthos. The Biological Assessment Unit does all the biological sampling in flowing waters, and after many years has determined how to evaluate swamp streams using benthos. There are several reasons for using biological surveys in monitoring water quality. Conventional water quality surveys do not integrate fluctuations in water quality between sampling periods. Therefore, short-term critical events may often be missed. The biota reflect both long and short term conditions, since many species in a community have life cycles of a year or more. Bioclassification criteria have been developed that assign a bioclassification to each biological sample. Stream and river reaches are given a final bioclassification of either Excellent, Good, Good/Fair, Fair or Poor. These bioclassifications, which have been developed for major ecoregions, are used to assess the various impacts of both point source discharges and nonpoint source runoff. About 200 sites are sampled each year during basinwide monitoring, and additional sites are sampled for special studies, especially TMDL stressor studies and for the EEP program. The resulting information is used to document both spatial and temporal changes in water quality, and to complement water chemistry analyses, ambient toxicity data, and habitat evaluations. In addition to assessing the effects of water pollution, biological information is also used to define High Quality or Outstanding Resource Waters, support enforcement of stream standards, and measure improvements associated with management actions. The results of biological investigations have been an integral part in North Carolina's basinwide monitoring program. Benthos FIsh Community To the public, the condition of the fishery is one of the most meaningful indicators of ecological integrity. Fish occupy the upper levels of the aquatic food web and are both directly and indirectly affected by chemical and physical changes in the environment. The Biological Assessment Unit employs a standard method for assessing streams' biological integrity by examining the structure and health of fish communities. This assessment incorporates information about species richness and composition, trophic composition, fish abundance and fish condition. At each sample site, a 600 foot section of stream is selected. The fish within the delineated stretch of stream are collected with the aid of backpack electrofishing units. Available data include: fish community raw data, fish community scores and ratings,and North Carolina fish distributions.Contact Bryn Tracy at 919.743.8474 for questions concerning fish community assessment. Fish Tissue Since fish spend their entire lives in the aquatic environment, they incorporate chemicals from this environment into their body tissues. Therefore, by analyzing fish tissue, determinations of what bioaccumulative chemicals are in the water can be made. Contamination of aquatic resources, including freshwater, estuarine, and marine fish and shellfish species have been documented for heavy metals, pesticides, and other complex organic compounds. Results from fish tissue monitoring can thus serve as an important indicator of contamination of sediments and surface water. View fish tissue contaminants across North Carolina by river basin here. Fish tissue monitoring data is also used by the NC Department of Health for issuing fish consumption advisories. A list of current fish advisories in North Carolina can be viewed here. Contact Jeff DeBerardinis at 919.743.8473 for questions concerning fish tissue contaminant assessment Also see the USEPA's page on bioindicators
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This page revised 8/6/09 |
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| NCGov.com |
Environmental Sciences Section 1621 Mail Service Center Raleigh, NC 27699-1621 919.743.8400 |