Chlorpyrifos interacts with other agricultural stressors to alter stream communities in laboratory microcosms

Chlorpyrifos is one of the most widely used agricultural insecticides in the world, but to date there is limited empirical information about its potential to interact with other common agricultural stressors. We conducted a 15-day, community-level microcosm experiment evaluating individual and combined effects of chlorpyrifos, nutrient enrichment, and sedimentation on stream invertebrate communities (abundance, biomass, richness, size structure, composition) and ecosystem processes (primary productivity and leaf decomposition). We found that sedimentation was the most detrimental stressor, with significant negative impacts on most invertebrate community and ecosystem function variables. Even though chlorpyrifos did not cause significant invertebrate mortality in the microcosms, it still altered ecosystem function by lowering leaf decomposition rates, probably through sublethal inhibition of invertebrate shredders. Furthermore, we observed a significant reversal interaction between chlor...