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THE INFLUENCE OF PHYSICAL FACTORS ON COMPARATIVE PERFORMANCE OF SAMPLING METHODS IN LARGE RIVERS
Citation:
Blocksom, K A. AND J E. Flotemersch. THE INFLUENCE OF PHYSICAL FACTORS ON COMPARATIVE PERFORMANCE OF SAMPLING METHODS IN LARGE RIVERS. Presented at North American Benthological Society, Pittsburgh, PA, May 28-June 1, 2002.
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:
In 1999, we compared five existing benthic macroinvertebrate sampling methods used in boatable rivers. Each sampling protocol was performed at each of 60 sites distributed among four rivers in the Ohio River drainage basin. Initial comparison of methods using key macroinvertebrate metrics suggested that certain methods provided similar results and were more likely to capture a larger proportion of the taxa at a site than other methods. However, several macroinvertebrate metrics (e.g., number of taxa, percent chironomids) showed relationships with physical characteristics of sites, and these trends sometimes varied among sampling methods. To control for the influence of depth and other physical characteristics before we compared sampling methods, we ran Principal Components Analysis on physical characteristics of sites. Results indicated that the first principal component, accounting for 43% of variation, was strongly related to reach depth. When sites were classified into two groups based on this depth-related principal component, there were obvious differences in some metric distributions (e.g., number of Diptera taxa). However, general patterns of differences among methods were not strongly affected by depth. Thus, this analysis demonstrated that depth did not affect the initial comparison of methods, despite its interaction with certain metrics.