Evaluation of cross-generational exposure to microplastics and co-occurring contaminants on embryonic and larval behavior in fathead minnows, Pimephales promelas

Microplastics (MPs) are ubiquitous in freshwater systems, and understanding their effects on aquatic organisms is increasingly important. Microplastics possess several unique surface properties that allow them to act as vectors for common environmental pollutants, such as endocrine disrupting chemicals (EDCs), which may serve as an additional route of exposure to those contaminants. However, few studies have considered the cross-generational effects of microplastics on early life-stage behaviors in aquatic vertebrates. In this study, adult fathead minnows, Pimephales promelas, were exposed to microplastics alone (MPVirgin) or in association with one of two environmentally relevant concentrations of 17 α-ethinyl estradiol (low; MPEE2 10 and high; MPEE2 50) for 30 days and then were allowed to spawn. Embryonic activity was assessed for F1 embryos of the MP-exposed F0 adults at 4 days post fertilization. After hatching, half of these larvae received continued exposure for 21 days, and larvae were tested in open-field swimming trials for swimming performance and space use. MPVirgin and MPEE2 50 embryos showed evidence of increased spontaneous activity within the egg, and similar trends in swimming activity persisted after hatching at day 21. These results suggest that parental exposure to MPs can induce subtle, sublethal effects on embryonic and larval performance that have the potential to affect individual fitness.

Methods
Adult fathead minnows, Pimephales promelas, were exposed to microplastics alone (MPVirgin) or in association with one of two environmentally relevant concentrations of 17 α-ethinyl estradiol (low; MPEE2 10 and high; MPEE2 50) for 30 days and then were allowed to spawn. Embryonic activity was assessed for F1 embryos of the MP-exposed F0 adults at 4 days post fertilization. After hatching, half of these larvae received continued exposure for 21 days, and larvae were tested in open-field swimming trials for swimming performance and space use. Data for embryos and larvae were collected using automated behavioral tracking software and exported as Excel worksheets.