Climate-change influences on the response of macroinvertebrate communities to pesticide contamination in the Sacramento River, California watershed

The authors modeled predictions for pesticide effects on macroinvertebrates using use data and a hydrological fate and transport model from 1970-1999 to forecast for 2070-2099. They used pesticide use data from 2009-2014 to create estimates for the baseline period, noting that the types of pesticides used change throughout time. Based on the relationship between macroinvertebrate communities and pesticide dynamics, the authors’ modeling predicted increased rainfall and warming, as well as increasing pesticide contamination and effects on macroinvertebrates during 2070-2099. Smaller increases in the effects of pesticides were predicted for downstream areas with intensive agriculture than for upstream areas with less-intensive agriculture. Climate change is predicted to directly influence pesticides by affecting their degradation and transport in water. Indirect effects could come from increased pesticide applications as a result of higher temperatures that increase pest pressure. The authors recommend considering mitigation measures for basins with current risk or predicted future risks, including buffers, application timing, irrigation efficiency, and integrated pest management strategies.