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Marine plastic pollution leaches chemicals that cause detrimental effects such as reduced fecundity and feminization of males in marine species. The eastern oyster, Crassostrea virginica, is a valuable species to study the effects of plastic on sex differentiation because it is a protandric hermaphrodite that undergoes gametogenesis yearly. My objective was to investigate a potential cause of an observed female-skew in the sex ratio of first year oysters exposed to plastic by measuring differential gene expression of eight gametogenesis genes from oysters grown on plastic compared to those on shell. Plastic exposure increased the expression of genes involved in egg production for females and reduced the variation in expression for males. The results suggest plastic may be altering gene expression in a way that results in a female-skewed sex ratio as observed in plastic-exposed oysters.