Effects of Environmentally-Relevant Concentrations of Microplastic Fibers on Pacific Mole Crab (Emerita analoga) Mortality and Reproduction

Microplastics are increasingly recognized as ubiquitous in marine systems, however, knowledge of the effects of these particles on marine fauna is limited. Ocean-borne plastic debris accumulates in littoral ecosystems around the world, and invertebrate infauna inhabiting these systems can ingest small plastic particles, mistaking them for food items. We examined the effect of microplastics on physiological and reproductive outcomes in a nearshore organism by exposing Pacific mole crabs (Emerita analoga), collected from Newport, Oregon, to environmentally relevant concentrations of micro-sized polypropylene rope fibers. We compared adult gravid female crab mortality, reproductive success, and egg developmental rates between microfiber-exposed and control crabs. Pacific mole crabs exposed to polypropylene rope had increased adult crab mortality, and decreased retention of egg clutches, and caused variability in egg development rates. These effects of microplastic ingestion on a nearshore prey item have implications for nearshore predators such as surf perf and shore birds, as plastic use, and resultant microplastic presence in nearshore environments increases.