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DEVELOPMENT OF STANDARDIZED LARGE RIVER BIOASSESSMENT PROTOCOLS (LR-BP) FOR FISH ASSEMBLAGES
Citation:
Flotemersch, J E. DEVELOPMENT OF STANDARDIZED LARGE RIVER BIOASSESSMENT PROTOCOLS (LR-BP) FOR FISH ASSEMBLAGES. Presented at Southeastern Water Pollution Biologists Association, Opelika, AL, November 01 - 04, 2004.
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
We conducted research comparing several methods currently in use for the bioassessment and monitoring of fish and benthic macroinvertebrate assemblages for large rivers. Fish data demonstrate that electrofishing 1000 m of shoreline is sufficient for bioassessments on boatable rivers similar to those in this study, regardless of whether the shoreline is along a single bank or distributed equally among paired banks. However, at sites with depths > 4 m, it may be advisable to employ nighttime electrofishing or increase day electrofishing distance to 2000 m. For benthic macroinvertebrates, we conducted a study using an experimental sampling method that is designed to overcome sampling limitations identified by previous research comparing several methods currently in use. Our objectives were to determine the appropriate number of sampling points needed, determine an appropriate laboratory subsample size, and to examine how varying reach lengths affect assemblage characteristics. Results indicated that, using the sampling method, a representative sample of the benthic macroinvertebrate fauna was collected by sampling both banks at 6 transects spaced at 100-m intervals over a 500-m distance. It is recommended that the field method be coupled with a fixed laboratory subsample size of 300 organisms for bioassessment purposes, with the recognition that a subsample size of 500 organisms may be needed to meet the objectives of some studies. It is likely this approach will over-sample sites of uniform composition, but the goal was to develop a standardized sampling protocol that would perform well across sites of differing habitat composition. However, resulting data should be interpreted with consideration of appropriate classification systems (e.g., ecoregion, free-flowing vs. impounded, tidal vs. non-tidal).