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COMPARISON OF MACROINVERTEBRATE SAMPLING METHODS FOR NONWADEABLE STREAMS
Citation:
Blocksom, K A. AND J E. Flotemersch. COMPARISON OF MACROINVERTEBRATE SAMPLING METHODS FOR NONWADEABLE STREAMS. ENVIRONMENTAL MONITORING AND ASSESSMENT 102:243-262, (2005).
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:
The bioassessment of nonwadeable streams in the United States is increasing, but methods for these systems are not as well developed as for wadeable streams. In this study, we compared six benthic macroinvertebrate field sampling methods for nonwadeable streams based on those used by three major programs (EMAP-SW, NAWQA, and Ohio EPA), at sixty sites across four tributaries to the Ohio River. Water chemistry samples and physical habitat measurements were collected at each site to assess relationships with macroinvertebrate metrics. Sites were divided into two groups: those influenced by navigational lock and dam structures built to support commercial traffic (restricted flow, or RF) and those free-flowing or having only lowhead dams (run-of-the-river, or ROR). The ROR and RF sites differed markedly in thalweg depth and substrate composition as well as macroinvertebrate composition. Regardless of site type, drift nets performed poorly and often could not be deployed due to inadequate flow. Metrics based on the passive Hester-Dendy artificial substrate samplers differed greatly from active sampling methods (i.e., D-frame and kick net sampling). Metric values were similar across active sampling methods, but the metrics significantly correlated with abiotic variables varied among methods and between ROR and RF sites. In both ROR and RF sites, active, net-based methods correlated with the most abiotic variables across metrics. These results emphasize that methods are not interchangeable, and the ability to detect certain stressors depends on the method of sampling.