Using 20 Years of Benthic Invertebrate Surveys by Multiple Agencies to Reveal Patterns of Community Structure Over Space and Time

State and federal agencies frequently conduct benthic macroinvertebrate surveys for bioassessment across large spatiotemporal scales. However, these data are rarely used outside specific regulatory agencies to address ecological questions. We assembled a dataset of benthic community information from 10 locations in the Susquehanna River and major tributaries collected by four federal and state agencies from 1991-2011. To account for differences in sampling, processing, and identification methods among agencies, we standardized sample size and resolved taxonomic ambiguities of 150 samples. Invertebrate communities were dominated by mayflies and caddisflies (45.6 to 83.2%) across all locations, and spatial patterns in certain invertebrate taxa were detected among major sub-basins of the Susquehanna River drainage. In addition, the dataset also documents the spread of Asian clams (Corbicula) and the impact of black fly (Simuliidae) management in the Susquehanna River. Percent EPT and community diversity measures were inversely correlated, indicating that traditional macroinvertebrate IBI approaches might not be applicable to large rivers. Large river invertebrates are understudied and, even with challenges of compiling multi-agency datasets, we show the value of applying these data to large river systems. Our analysis also suggests changes to future biomonitoring protocols to improve their effectiveness in bioassessment and ecological applications