Final Bulk Sediment Concentrations of Bifenthrin from Mesocosms
Dates
Publication Date
2016
Start Date
2014-11-18
End Date
2014-12-19
Citation
Schmidt, T.S., Rogers, H.A., Hladik, M.L., Dabney, B.L., Mahler, B.J., Van Metre, P.C., 2016, Bifenthrin causes trophic cascade and altered insect emergences in mesocosms: implications for small streams: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F7SX6BBZ.
Summary
Direct and indirect ecological effects of the widely used insecticide bifenthrin on stream ecosystems are largely unknown. To investigate such effects, a manipulative experiment was conducted in stream mesocosms that were colonized by aquatic insect communities and exposed to bifenthrin-contaminated sediment; implications for natural streams were interpreted through comparison of mesocosm results to a survey of 100 Midwestern streams, USA. In the mesocosm experiment, direct effects of bifenthrin exposure included reduced larval macroinvertebrate abundance, richness, and biomass at concentrations (EC50s ranged 197.6 – 233.5 ng bifenthrin/ g organic carbon) previously thought safe for aquatic life. Indirect effects included a trophic [...]
Summary
Direct and indirect ecological effects of the widely used insecticide bifenthrin on stream ecosystems are largely unknown. To investigate such effects, a manipulative experiment was conducted in stream mesocosms that were colonized by aquatic insect communities and exposed to bifenthrin-contaminated sediment; implications for natural streams were interpreted through comparison of mesocosm results to a survey of 100 Midwestern streams, USA. In the mesocosm experiment, direct effects of bifenthrin exposure included reduced larval macroinvertebrate abundance, richness, and biomass at concentrations (EC50s ranged 197.6 – 233.5 ng bifenthrin/ g organic carbon) previously thought safe for aquatic life. Indirect effects included a trophic cascade in which periphyton abundance increased after macroinvertebrate scrapers decreased. Adult emergence dynamics and corresponding terrestrial subsidies were altered at all bifenthrin concentrations tested. Extrapolating these results to the Midwestern stream assessment suggests pervasive ecological effects, with altered emergence dynamics likely in 40% of streams and a trophic cascade in 7% of streams. This study provides new evidence that a common pyrethroid might alter aquatic and terrestrial ecosystem function at the regional scale. This data file contains information about the bifenthrin concentrations measured in sediment collected from mesocosms at the end of the experiment.
We conducted an experiment that simulated a single runoff event delivering bifenthrin adsorbed to suspended sediments to mesocosm streams, the most likely transport mechanism of bifenthrin to receiving streams and thus a likely exposure scenario for stream invertebrates. This experiment accompanied a regional assessment of streams across the Midwestern USA. The purpose of the stream experiment was to assess the direct and indirect effects of sediment-bound bifenthrin on natural aquatic communities under controlled conditions and compare those responses on day 30 with observations from the field assessment. Specifically, the direct (mortality) and indirect (altered ecological processes) effects of bifenthrin on benthic communities (larval insects and periphyton communities) and on adult aquatic insects were assessed in a manipulative experiment and extrapolated to a field survey of streams to improve causal linkages in the field study conclusions.
