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Evaluation of an alternate method for sampling benthic macroinvertebrates in low-gradient streams sampled as part of the National Rivers and Streams Assessment
Citation:
Flotemersch, J., S. North, AND K. Blocksom. Evaluation of an alternate method for sampling benthic macroinvertebrates in low-gradient streams sampled as part of the National Rivers and Streams Assessment. ENVIRONMENTAL MONITORING AND ASSESSMENT. Springer, New York, NY, 186(2):949-959, (2014).
Impact/Purpose:
This research was conducted at the request of the OW/OWOW NARS program. The purpose of this study was to research the value of a proposed alternate field method for use in collecting benthic macroinvertebrates from low gradient streams as part of the National Rivers and Streams Survey It researched the value of a field method
Description:
Benthic macroinvertebrates are sampled in streams and rivers as one of the assessment elements of the U.S. Environmental Protection Agency’s National Aquatic Resource Surveys. In a 2006 report, the recommendation was made that different yet comparable methods be evaluated for different types of streams (e.g., low gradient vs. high gradient). Consequently, a research element was added to the 2008-2009 National Rivers and Streams Assessment to conduct a side-by-side comparison of the standard method with a test method specifically designed for low-gradient wadeable streams and rivers. The two methods differed in that the test method had a focus on inclusion of stream edge habitat features. Data used for this study was collected from 536 sites in five of nine aggregate Omernik ecoregions located in the conterminous United States. Data from the two methods were compared using the benthic macroinvertebrate multimetric index developed for the 2006 Wadeable Streams Assessment report. Statistical analysis of these data did not reveal any trends which would suggest that the overall assessment of low-gradient streams on a regional or national scale would change if the test method was used, regardless of the gradient cut-off used to define low-gradient streams. Based on these results, we recommend that the National Rivers and Streams Survey continue to use the standard field method for sampling all streams until statistical evidence is presented, or an alternate method developed and tested, that suggests otherwise.
