Assessing Changes in Permethrin Toxicity to Juvenile Inland Silversides (Menidia beryllina) Under Different Temperature Scenarios

Aquatic systems are impacted by temperature fluctuations which can alter the toxicity of pesticides. Increased temperatures related to climate change have elevated pest activity, resulting in an escalation of pesticide use. One such pesticide class, pyrethroids, has replaced the use of several banned pesticides due to its low mammalian toxicity. The impacts of increased temperatures on the toxicity of a pyrethroid, permethrin, to fish is not yet known. In the current study, juvenile inland silversides (Menidia beryllina) were exposed to permethrin at three temperatures: 10 °C, 20 °C, and 30 °C. Inland silversides were chosen for this study because they are a species used in standardized USEPA whole effluent toxicity testing. Permethrin toxicity showed an inverse relationship with temperature. As temperatures fluctuate, fishes experience a change in respiration, biotransformation, and elimination rates, which can drive the noted difference in toxicity. Based on these findings, toxicity can be temperature-dependent and should be considered when assessing risk of exposure to pesticides in aquatic systems.