Linking mechanistic and behavioral responses to sublethal esfenvalerate exposure in the endangered delta smelt; Hypomesus transpacificus (Fam. Osmeridae)

Connon, Richard E; Geist, Juergen; Pfeiff, Janice; Loguinov, Alexander V; D'Abronzo, Leandro S; Wintz, Henri; Vulpe, Christopher D; Werner, Inge

Effects of esfenvalerate exposure: mortality and swimming behavior Fish larvae are known to be highly sensitive to esfenvalerate, with effects on swimming performance and enhanced susceptibility to predation resulting from concentrations as low as 0.0625 μg/L -1 [10] . Behavior alterations are construed as being consequential to the reported neurological mode of action of this pesticide, further affecting foraging, migration and reproduction [30] . Toxicity of pyrethroids in the Sacramento-San Joaquin estuary is likely alleviated by the presence of particles and organic matter, and to date concentrations of esfenvalerate detected in the water column were low, however, concentrations in winter storm runoff from agricultural lands have been reported up to 0.093 μg.L -1 [31] , influencing our decision to investigate dose response exposures to both high and environmentally relevant concentrations in confirmatory studies.