Impacts of sediment-bound synthetic pyrethroids on non-target aquatic macroinvertebrates

BOYLE, R.; LONG, S.; MARSHALL, S.; PETTIGROVE, V.; BALLESTEROS, M.L; HOFFMANN, A.A.,

Berlin

Congreso; 6th SETAC World Congress / SETAC Europe 22nd Annual Meeting; 2012

When in the water column, synthetic pyrethroids have a high acute toxicity to many aquatic macroinvertebrates. However, they rapidly bind to sediment, where they potentially threaten macroinvertebrates through chronic exposure. The effects of such exposure, which may include impacts on life cycle parameters, are less well understood. In addition, there is a need for biomonitoring tools to identify synthetic pyrethroid contamination, in particular subcellular biomarkers that can be linked to organism and community level effects. We aimed to identify and link the effects of two synthetic pyrethroids at these three levels of organization. Laboratory toxicity tests and field microcosms were used to examine the effects of sediment-bound bifenthrin and permethrin on survival and life cycle parameters of aquatic macroinvertebrates. This dual-pronged approach benefits from both the highly controlled approach of lab exposures, and the more environmentally relevant approach of the microcosms, which includes natural environmental conditions and community interaction. This work also incorporates the identification of biochemical biomarkers produced by exposed macroinvertebrates, in order to develop biomarkers that indicate effects at the whole organism and community levels. In the laboratory toxicity tests, clean field-collected sediment was spiked with either bifenthrin or permethrin at concentrations of 12.5, 25 and 50 μg/kg. Second instar Chironomus tepperi larvae were placed in beakers containing spiked sediment. At 50 μg/kg of bifenthrin, the number of larvae surviving after five days was lower than that of the controls, however the body length of surviving larvae was not affected. Two weeks of exposure to bifenthrin did not affect the total number or sex ratio of emerged adults. Results for permethrin will be discussed. In the microcosm experiments, clean field-collected sediment was spiked with a range of concentrations of either permethrin bifenthrin from 8.9 μg/kg to 500 μg/kg. This sediment was placed in wetland microcosms, where colonization by macroinvertebrates was permitted. Emerged adults were collected over several weeks and identified to species level. The chironomid Paratanytarsus grimmii showed significantly reduced emergence at concentrations of permethrin above 35.5 μg/kg. Results for bifenthrin will be discussed, as will the links between subcellular biomarkers and effects on whole organism parameters and community composition.