Potential Pathway and Hormonal Disrupting Capacity of Microplastic in a Coastal System

Plastic pollution is resulting in a widespread crisis of plastic ingestion by marine species. Microplastic particles (smaller than 5 mm) are particularly concerning as they can remain in the digestive system and allowing for plastic-associated chemicals to desorb into tissue. Many of these hydrophobic additive chemicals are xenoestrogenic and can disrupt the endocrine system. We will investigate the potential pathway of microplastic exposure in a marine food web by quantifying microplastics in seawater, northern anchovies ( Engraulis mordax ), and common murres ( Uria aalge ) from the Monterey Bay National Marine Sanctuary, California. We hypothesize that i) microplastics will be present in seawater, prey fish, and seabirds with similar ratios of particle types (e.g., fibers versus beads), ii) recovered microplastic from seawater will have more hormonal disrupting activity than microplastics from fish or seabirds. Three promising techniques for microplastic quantification and estrogenicity will be tested: tissue digestion with 20% potassium hydroxide for extraction, and Raman spectroscopy for plastic validation, and the estrogen-receptor activation assay. To our knowledge, our study is the first to target ingested microplastics in common murres, first to measure estrogenic activity of plastic-associated chemicals extracted from ingested microplastic, and first to link the knowledge gaps of quantification and toxicity assessments of ingested microplastics while still using standardized methods.