Chronic, low concentration pesticide exposure alters reproduction and behavior in the intertidal sea anemone, Anthopleura elegantissima

Widespread pesticide and herbicide use paired with frequent transport away from application sites has led to pesticide presence in nearly all terrestrial and aquatic environments globally. Pesticides have unintentional toxic effects on non-target organisms by interfering with cellular processes, behavior, feeding, reproduction, and disrupting endocrine processes. The aggregating anemone, Anthopleura elegantissima, is an important species along the North American Pacific coast due to its symbiotic relationships that contribute to high productivity, and its clonal abundance that structures the rocky intertidal habitat. Commonly used pesticides, atrazine, diuron, and carbendazim were previously detected in coastal waters of Oregon, U.S.A. This study examined the potential effects of these pesticides at environmentally relevant concentrations on reproduction, symbionts, and behavior of A. elegantissima over an eight-week period. Pesticides significantly decreased gonad development in all treatments, having the most significant effect in individual treatments of atrazine (p = 0.003), carbendazim (p = 0.003), and the mixture of all three pesticides (p = 0.008). All pesticide treatments significantly increased cloning behavior compared to the control, suggesting that cloning could be a stress response. Pesticide exposure also significantly increased tentacle retraction movement, suggesting possible metabolic or energy impairments. While other studies have previously found behavioral changes in anemones due to pollutants, our study is the first to document behavioral changes in anemones from pesticide exposure. All three pesticides significantly impacted a non-target marine invertebrate at environmentally relevant concentrations, which underscores the value of studies that focus on effects on marine invertebrates, paired with comprehensive pesticide monitoring in coastal areas.