Bifenthrin causes trophic cascades and alters insect emergence in mesocosms: implication for small streams

Environmental Science & Technology
By: , and 

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Abstract

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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Bifenthrin causes trophic cascades and alters insect emergence in mesocosms: implication for small streams
Series title Environmental Science & Technology
DOI 10.1021/acs.est.6b02761
Volume 50
Issue 21
Year Published 2016
Language English
Publisher ACS Publications
Publisher location Washington, D.C.
Contributing office(s) Colorado Water Science Center, California Water Science Center
Description 10 p.
First page 11974
Last page 11983