Environmental effects and fate of the insecticide bifenthrin in a salt-marsh mesocosm

•We examined the lethal and sublethal effects of bifenthrin on shrimp and fish.•Bifenthrin was toxic to shrimp at environmentally relevant levels.•Bifenthrin had no effect on oxidative stress assays in shrimp or fish.•Bifenthrin was rapidly eliminated from the water column.•Bifenthrin readily partitioned to sediments. Bifenthrin is a widely used synthetic pyrethroid insecticide that is often applied to crops, turf, and residential structures for the control of insects. Like other insecticides, bifenthrin has the potential to contaminate bodies of water that are adjacent to the application site via spray drift and runoff during storm events. The objective of this study was to examine the lethal and sublethal effects of bifenthrin on grass shrimp, Palaemonetes pugio, and sheepshead minnow, Cyprinodon variegatus in a 28d mesocosm experiment under estuarine conditions. Endpoints included mortality and growth and the oxidative stress biomarkers of lipid peroxidation, glutathione, and catalase. In the mesocosm experiment, 24h and 96h caged shrimp LC50s were 0.061 and 0.051μgL−1, respectively. The uncaged grass shrimp 28d LC50 was 0.062μgL−1. Fifty percent mortality was not reached in the uncaged sheepshead minnow. Bifenthrin did not have a significant effect on the growth of the shrimp, but there was an increasing impact on fish growth. However, it is uncertain as to whether this pattern is a direct effect of the chemical or if it is due to increased food availability resulting from mortality in prey species. The oxidative stress assays were largely inconclusive. Bifenthrin was eliminated rapidly from the water column and readily partitioned to sediments. The LC50s for adult and larval P. pugio were below published Estimated Environmental Concentration (EEC) values and were within the range of bifenthrin concentrations that have been measured in rivers, channels, and creeks.