Citation:

ANGRADI, T. R. AND T. M. JICHA. Mesohabitat-specific Macroinvertebrate Assemblage Responses to Water Quality Variation in Mid-continent (North America) Great Rivers . ECOLOGICAL INDICATORS. Elsevier Science Ltd, New York, NY, 10(5):943-954, (2010).

Impact/Purpose:

To hypothesize that the greater per sample and total taxa richness in the benthos increased the likelihood that sensitive taxa were included in samples.

Description:

We compared the responsiveness of macroinvertebrate assemblages to water quality stressors (ions, nutrients, dissolved metals and suspended sediment) in two mesohabitats within the main-channel macrohabitat of three mid-continent North American rivers, the Upper Mississippi, Missouri, and Ohio. We compared the responsiveness of benthic assemblage sampled in the main channel littoral zone with assemblages sampled from the surface of woody snags in the main channel. The assemblages in the two mesohabitats were consistently (along the length of the river) quite different, indicating the two mesohabitats might respond differently to stressors. Taxa richness was much higher on snags. Macroinvertebrate assemblage response to water quality stressors was weak on the Mississippi River, probably due to high multi-scale habitat variation within and among navigation pools. For the Missouri and Ohio Rivers, correlations between the assemblage structure and assemblage-based metrics with water quality stressor gradients were slightly higher and more numerous for the littoral benthos than for snags. The responsiveness of assemblage-based metrics was more similar for ions (SO4, Cl) than for other stressors. A multimetric index trained to respond to SO4 gradients explained 25% of the variation in SO4. We hypothesize that the greater per sample and total taxa richness in the benthos increased the likelihood that sensitive taxa were included in samples.

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