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A STANDARDIZED ASSESSMENT METHOD (SAM) FOR RIVERINE MACROINVERTEBRATES
Citation:
Blocksom, K A., J E. Flotemersch, AND J J. Hutchens. A STANDARDIZED ASSESSMENT METHOD (SAM) FOR RIVERINE MACROINVERTEBRATES. Presented at North American Benthological Society, Athens, GA, May 27-31, 2003.
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:
A macroinvertebrate sampling method for large rivers based on desirable characteristics of existing nonwadeable methods was developed and tested. Six sites each were sampled on the Great Miami and Kentucky Rivers, reflecting a human disturbance gradient. Samples were collected from 12 transects at specific intervals totaling 40 times the wetted width of each site. Timed kick-net and dip-net samples were composited for each transect and bank. All organisms up to 2000 individuals were sorted from each sample. For analysis, data from successively longer distances were combined across banks, and 300-organism random subsamples were simulated 100 times per sample. Richness metrics leveled off within 500 m, and percentage metrics varied little with distance. We then simulated 100- to 800-organism subsamples from composite samples based on a 500-m sampling distance. Subsampling 300 organisms provided good site separation based on richness metrics, and percentage metric values were unaffected by subsample size. A 500-m sampling distance and a 300-organism subsample are recommended for the SAM for macroinvertebrates in these and similar large rivers. The SAM contains both systematic and subjective components that are complementary and represent the assemblage in a logistically efficient manner.