The impact of channelization on macroinvertebrate bioindicators in small order Illinois streams: insights from long-term citizen science research

Abstract

Channelization can have far-reaching and long-term impacts on stream ecology. In this study, we demonstrate that channelization is associated with lower stream quality as measured by macroinvertebrate bioindicators when compared to unchannelized streams. Citizen scientists collected the data for this study between 1995 and 2014, performing 3021 sampling events during the months of May and June across 567 Illinois streams. We found significantly lower taxa richness, EPT taxa richness, and macroinvertebrate biotic index values in channelized sites. Our findings also show prevalent siltation in channelized sites that is likely negatively affecting macroinvertebrates, along with a possible lower availability of quality habitat. We also measured stream velocity and found that average velocity did not differ between our channelized and unchannelized sites. Our findings suggest stream velocity was not a driving factor in determining the differences in macroinvertebrate assemblages, although we cannot comment on the possible change in velocity from pre to post channelization at each site. This study allows for a large dataset that covers diverse streams across the entire state of Illinois. Our work provides example and encouragement for other researchers to take advantage of the power of citizen science, and the existing large datasets available from these projects.