Meeting Abstract

P1-34    Elucidating the effects of acute and chronic exposure to 2,4-Dichlorophenoxyacetic acid on fathead minnow (Pimephales promelas) innate immunity Cornelius Ruhs, E; Anton, B; Dehnert, DK*; University of Chicago; University of Wisconsin-Madison; University of Wisconsin-Madison, Wisconsin Sea Grant cornelius.emily@gmail.com https://emilycorneliusruhs.weebly.com/

or potentially eradicate these invasive species, management agencies commonly apply aquatic herbicides. One of the most commonly used active ingredients to combat invasive species (e.g Eurasian watermilfoil; Myriophyllum spicatum) is 2,4-Dichlorophenoxyacetic acid (2,4-D). Ecologically relevant concentrations of 2,4-D have been shown to negatively impact the development and survival of early life stages of multiple freshwater fish species, decrease the cortisol stress response in fathead minnow larvae, and inhibit essential behaviors in multiple freshwater fish species. Despite our growing knowledge on the effects of 2,4-D, the impacts of acute and chronic exposure to 2,4-D on the overall health of fish is mostly unknown. Here, we investigate the acute and chronic exposure impacts of 2,4-D on adult male and female fathead minnow (Pimephales promelas) innate immune function and compare sex differences. To test this hypothesis we exposed both adult, male and female fathead minnows to three different concentrations of 2,4-D (0.00, 0.40, and 4.00 mg/L) and took blood samples at three acute time points (6, 12, and 96 hours) and one chronic time point (31 days). We predict that exposure to 2,4-D increases total white blood cell (wbc) counts on an acute timeline, primarily driven by an increase in lymphocytes and decrease in neutrophils, and that wbc levels would begin to return to near-normal levels at the chronic time point. We also expect that the degree of these impacts are likely to differ by sex. Overall, this study begins to elucidate the subchronic impacts of 2,4-D exposure on fishes health and immunity and provides more data to help management agencies accurately create risk assessments for herbicide treatments in aquatic ecosystems.