Citation:

Rashleigh, B. RELATION OF ENVIRONMENTAL CHARACTERISTICS TO FISH ASSEMBLAGES IN THE UPPER FRENCH BROAD RIVER BASIN, NORTH CAROLINA. ENVIRONMENTAL MONITORING AND ASSESSMENT 93(1-3):139-156, (2004).

Impact/Purpose:

This research project sets out to design and conduct an assessment of the long-term ecological consequences of alternative management choices. As the first project to be done at this scale using predictive ecological endpoints, we will seek to identify the appropriate components of such an analysis. We will use experience gained in the conduct of this BASE analysis to identify key research and data needs for address, to estimate timing, resource needs, etc., for future analyses. We will extend this analysis beyond previous and ongoing studies in two ways: by incorporating biological endpoints, primarily properties of fish communities, and by introducing the concept of sustainability of ecological state under future scenarios contrasted with the present state of those same ecological resources. Requirements that are identified during the course of this study will permit the recommendation of specific capabilities that should be incorporated in a general modeling system currently under development to support BASE and other environmental assessments. Finally, the analysis is intended to be of value for establishing environmental management choices that will be beneficial and those that would be detrimental to the sustainability of ecological resources of the Albemarle-Pamlico Basin.

Description:

Fish assemblages at 16 sites in the upper French Broad River basin, North Carolina were related to environmental variables using detrended correspondence analysis (DCA) and linear regression. This study was conducted at the landscape scale because regional variables are controlled so that patterns of anthropogenic influence dominate, and because management activities and decisions are most likely to occur at this scale. Environmental variables found most useful for explaining differences among sites were related to agricultural influence; they were agricultural land cover, nitrate-nitrite, sulfate, conductance, and sediment. Agricultural influence on the fish assemblage was represented as a trophic shift from specialized insectivores to one herbivore and generalized insectivores. A secondary influence among sites was related to urban land cover, population density, high concentrations of metals, stream gradient, and soil erodibility. This primarily urban gradient was characterized by an increase in the number of introduced species, sunfish, and other native species. It was shown that the agricultural gradient had a different effect on fish assemblages than the urban gradient. This finding can improve our ability to diagnose impairment in this basin and in similar basins.

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