MICROPLASTIC INTERACTIONS AND EFFECTS ON Crassostrea virginica LARVAE

Microplastic pollution is a complex global issue, with millions of tons of plastic reaching marine ecosystems yearly. Oysters are keystone species, providing vital ecosystem services and, as filter feeders, they encounter high numbers of suspended particles. Therefore, oysters are highly susceptible to microplastic pollution exposure. Although microplastic effects on adult life stages of filter feeding bivalves have been studied, effects on larval life stages have fewer observations. This research examined the interactions and effects of microplastic ingestion on the larval stage of Crassostrea virginica and developed a method to manufacture standardized microfibers to make laboratory exposure experiments more environmentally relevant. Initial experiments addressed factors affecting larval microplastic ingestion, microplastic ingestion capacity, and egestion. In subsequent experiments, I exposed oyster larvae to microplastics of various sizes, particle types, and polymers, at ingestion threshold concentrations, using physiological effects from ingestion to determine early life stage effects. Larval oysters readily ingested microplastics. Food availability was not a factor for microplastic ingestion but microplastic concentrations of exposure solutions were important. Microplastic ingestion followed a saturation curve model, with saturation occurring at extremely high concentrations. As microplastic pollution increases in the environment, larval oysters will increase their ingestion of plastic particles. However, microbead ingestion did not cause significant physiological effects and experiments on microfiber ingestion suggested minimal effects on physiology. Therefore, microplastics likely pose minimal risks to larval oysters with current and near future environmental microplastic pollution levels. In this dissertation, I provide the first observations regarding the interactions and effects of microplastic pollution on the larval life stage of bivalve filter feeders