(2nd Place) How clean is our stream? Investigating the ecotoxicological influence of emerging contaminants on aquatic macroinvertebrate communities

Aquatic benthic macroinvertebrates are critical indicators of water quality and stream health. Aquatic taxa vary widely in their sensitivity to pollutants, so assessing their communities can provide insights into the health of streams. While causes of surface-water impairment in agriculturally dominated watersheds are often excess sediment or nutrients, emerging contaminants (ECs), such as pharmaceuticals, personal care products, and pesticides, may also negatively influence macroinvertebrate diversity. To gain an insight on the influence of ECs on macroinvertebrate communities, we studied the Spruce Creek watershed in central Pennsylvania. Using active and passive sampling across nine sites, we sampled water from June 2021 to September 2022. We then analyzed the samples with orbitrap mass spectrometry to identify spatial and temporal trends of 46 ECs, including pharmaceuticals, personal care products, and pesticides. To assess the potential ecotoxicological influence of contaminants, during this time, we also sampled benthic macroinvertebrate communities in May and November 2021 and 2022 following protocol from the Pennsylvania Department of Environmental Protection and calculated indices (Index of Biotic Integrity, SPEAR_pesticide) and toxicity units. We found that EC concentrations vary strongly over the seasons, with the highest concentrations and greatest ecotoxicity threats in spring/summer. Agricultural chemicals, including the herbicide simazine and the insecticide clothianidin, were the most commonly detected contaminants, being detected in 97% of samples. SPEAR_pesticide results revealed an elevated risk of ECs to macroinvertebrate communities. We will use these data to develop controlled mesocosm experiments to better understand the ecotoxicological effects of these contaminants on sensitive macroinvertebrate species.