Comparative behavioral ecotoxicology of Inland Silverside larvae exposed to pyrethroids across a salinity gradient

• Published in: The Science of the total environment 2023-01, Vol.857, p.159398-159398, Article 159398
• Main Authors: Hutton, Sara J., Siddiqui, Samreen, Pedersen, Emily I., Markgraf, Christopher Y., Segarra, Amelie, Hladik, Michelle L., Connon, Richard E., Brander, Susanne M.
• Format: Article
• Language: English
• Subjects: Climate change; Drought; Ecotoxicology; Insecticide; Marine; Menidia beryllina
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.159398

Pyrethroids, a class of commonly used insecticides, are frequently detected in aquatic environments, including estuaries. The influence that salinity has on organism physiology and the partitioning of hydrophobic chemicals, such as pyrethroids, has driven interest in how toxicity changes in saltwater compared to freshwater. Early life exposures in fish to pyrethroids cause toxicity at environmentally relevant concentrations, which can alter behavior. Behavior is a highly sensitive endpoint that influences overall organism fitness and can be used to detect toxicity of environmentally relevant concentrations of aquatic pollutants. Inland Silversides (Menidia beryllina), a commonly used euryhaline model fish species, were exposed from 5 days post fertilization (~1-day pre-hatch) for 96 h to six pyrethroids: bifenthrin, cyfluthrin, cyhalothrin, cypermethrin, esfenvalerate and permethrin. Exposures were conducted at three salinities relevant to brackish, estuarine habitat (0.5, 2, and 6 PSU) and across 3 concentrations, either 0.1, 1, 10, and/or 100 ng/L, plus a control. After exposure, Inland Silversides underwent a behavioral assay in which larval fish were subjected to a dark and light cycle stimuli to determine behavioral toxicity. Assessment of total distanced moved and thigmotaxis (wall hugging), used to measure hyper/hypoactivity and anxiety like behavior, respectively, demonstrate that even at the lowest concentration of 0.1 ng/L pyrethroids can induce behavioral changes at all salinities. We found that toxicity decreased as salinity increased for all pyrethroids except permethrin. Additionally, we found evidence to suggest that the relationship between log KOW and thigmotaxis is altered between the lower and highest salinities. [Display omitted] •Behavior is altered following exposure to pyrethroids at concentrations as low as 0.1 ng/L.•At the lowest salinity, inland silversides exposed to cypermethrin had increased anxiety like behavior.•Larvae exposed to permethrin were hypoactive and displayed decreased thigmotaxis.•Bifenthrin caused the fewest behavioral changes.•This is the largest comparison of pyrethroid toxicity across altered abiotic conditions.