An index of biotic integrity for macroinvertebrate stream bioassessment conducted by community scientists

Community science bioassessment has great potential to inform comprehensive stream management plans, but regional analytical tools are needed to evaluate macroinvertebrate data collected through community science programs. To this end, we modified a pre-existing professional index of biotic integrity (IBI) to create a community science IBI (CS-IBI), designed for stream macroinvertebrate data collected by community scientists with minimal training. We used data collected by both professional and community scientists to develop, calibrate, and validate the CS-IBI at 76 streamsites in the Puget Lowland andWillamette Valley ecoregions of the PacificNorthwest in theUnited States. Community science data were taxonomically coarser andmore variable than data generated by professionals; however, IBI scores and assemblage data were statistically similar between community science and professional data. Stream impairment categories classified by family-level CS-IBI scores matched genus-level professional classifications 65% of the time and never diverged by >1 category. CS-IBI scores were negatively related to the percentage of agriculture and land development in the watershed, although this relationship was weaker than for professional IBI scores. Despite increased variability in data generated by community scientists, our findings suggest the CS-IBI performs similarly to a professional IBI across a gradient of human influence. Although we do not advocate using the CS-IBI in regulatory settings, we believe the development of community science IBIs enhances, expands, and strengthens public partnerships, thereby supporting environmental managers’ efforts to monitor and restore degraded streams and rapidly respond to pollution events. Our hope is that the CS-IBI will improve the applicability of community science bioassessment data and serve as a model for how agencies can develop regionalized macroinvertebrate IBIs for use in comprehensive watershed management plans.