A Comparison Among Three Sampling Methods to Calculate Biotic Integrity in the Greater Blue Earth River Basin

The Blue Earth River watershed in south central Minnesota has been dramatically impacted by the surrounding land use. Consequently, high sediment loads and degraded water quality are the outcomes. To gauge stream health, benthic macroinvertebrates and ichthyofauna (fish) may be utilized as biotic indicators because they respond to changes, both positive and negative, in the aquatic environment. We compared fish and macroinvertebrate Index of Biotic Integrity (IBI) methods at several different sites within the Blue Earth River watershed to determine if one method could serve as an efficient and reliable technique. Macroinvertebrates were collected using Hester-Dendy artificial substrate samplers and d-frame dipnets. Fish were collected by fall electrofishing. Data were analyzed and IBIs were calculated using the EPA Rapid Bioassessment Protocol. Early results suggest that IBI values are significantly different among the three methods and that macroinvertebrate IBIs are more practical to use when comparing a wide variety of stream orders