Climate change is causing changes in precipitation patterns and contributing to increased sea levels. These alterations are linked with changes in salinity in estuaries, making the differences in toxicity across a salinity gradient a topic of increasing interest in assessing risk to estuarine fish species. Several recent studies have shown that pyrethroid toxicity can change across a salinity gradient. Pyrethroid pesticides are commonly used globally in agricultural, industrial, and household settings and have been detected in watersheds globally. Early life exposures in fish to pyrethroids has been found to cause toxicity at environmentally relevant concentrations and alter behavior, which has been demonstrated to be a sensitive endpoint that can detect toxicity of environmentally relevant concentrations of aquatic pollutants. Therefore, Inland Silversides (<i>Menidia beryllina</i>), a commonly used euryhaline, model fish species, were exposed from 5 days post fertilization (approximately 1-day pre-hatch) for 96 hours to six pyrethroids: bifenthrin, cyfluthrin, cyhalothrin, permethrin, cypermethrin, and esfenvalerate. Exposures were conducted at three salinities relevant to brackish, estuarine habitat (0.5, 2, and 6 PSU) and 3 concentrations, either 0.1, 1, 10, and/or 100 ng/L, determined from previous experiments to be sublethal and environmentally relevant. After exposure, Silversides underwent behavioral assays and were subjected to a dark and light cycle to determine behavioral toxicity. Results show significant behavioral changes with each pyrethroid exposure at all salinities and concentrations. These results indicate that there may be different behavioral responses to pyrethroids depending on pyrethroid and salinity. These data will provide knowledge to managers and environmental planners to help further protect threatened and endangered fishes in estuarine and bay regions.

Influence of salinity on pyrethroid toxicity: Behavior in a model estuarine organism (<i>Menidia beryllina</i>)

ACS Spring 2022

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Influence of salinity on pyrethroid toxicity: Behavior in a model estuarine organism (Menidia beryllina)