Benthic macroinvertebrates are aquatic insects that live near the stream bed. OBMEP collects benthic macroinvertebrates at all transect-based habitat sites. The primary use of macroinvertebrate data will be as a response variable that relates to physical habitat changes monitored at these same sites.
Macroinvertebrate data are needed to maintain a high level of coordination with planners and other data collection agencies from the region in the United States and Canada and are mostly used to document watershed health and as a potential early indicator of habitat changes that might later impact fish species.
Macroinvertebrates are sampled in an eight square foot area per habitat site. A D-frame kick net is placed in the selected sampling location with the open end of the net facing upstream. Eight separate one-foot-square areas of substrate in front of the net are disturbed and the insects are washed downstream into the net. Any large rocks, sticks, or other debris are removed from the samples before they are placed in containers and preserved with 95% ethanol.
Samples are sent to an independent laboratory for review and analysis. Metrics are calculated for all samples from each site, including numbers of ephemeroptera, plecoptera, and trichoptera, percent dominance of the top three taxa, percent of sediment tolerant and intolerant species, percent shredders, the Hilsenhoff Biotic Index, and the B-IBI score.
Invertebrate Sampling Protocols
Invertebrate Sampling Reports