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RIVERINE ASSESSMENT USING MACROINVERTEBRATES: ALL METHODS ARE NOT CREATED EQUAL
Citation:
Blocksom, K A. AND J E. Flotemersch. RIVERINE ASSESSMENT USING MACROINVERTEBRATES: ALL METHODS ARE NOT CREATED EQUAL. Presented at Biological Advisory Committee Meeting, Washington, DC, October 7-10, 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 six benthic macroinvertebrate field sampling methods for nonwadeable streams based on those developed for three major programs (EMAP-SW, NAWQA, and Ohio EPA), at each of sixty sites across four tributaries to the Ohio River. Water chemistry samples and physical habitat measurements were also collected at each site to assess relationships with macroinvertebrate metrics. Sites were divided into two groups: those heavily influenced by navigational lock and dam structures built to support commercial traffic or for creation of reservoirs (restricted flow, or RF) and those free-flowing or having lowhead dams that store rather than regulate waters (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 the type of site, 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 the active sampling methods (i.e., D-frame and kick net sampling) for ROR sites. However, metric values differed little among active sampling methods at these sites. At RF sites, there was little variation in metric values among methods. Despite similarities in metric values, the metrics having significant correlations with abiotic variables varied among methods and between ROR and RF sites. These results emphasize that methods are not interchangeable, and the ability to detect certain stressors depends on the method of sampling.