Plastic pollution is ubiquitous in the oceans, and numerous studies have documented the dangers from entanglement, ingestion, or exposure to individual xenoestrogenic plastic additives. Plastic degradation in seawater poses a complex threat through sorption of harmful organic pollutants, release of complex chemical ingredients that compose plastics, and fragmentation of plastic pieces. Therefore, a more holistic approach is needed to understand the impact of plastic exposure on marine organisms. The eastern oyster (Crassostrea virginica) is a keystone species that serves as an ecosystem engineer in western Atlantic estuaries. Individuals undergo annual gametogenesis and are able to change sex from one year to the next, typically from male to female. A 1:1 sex ratio is maintained at the population level by younger/smaller oysters that are mostly male and older/larger oysters that are mostly female. As sessile bivalves, oysters are susceptible to damaging effects from plastic that settle on the seafloor. The objective of this study was to quantify changes in survival, growth, sex ratio, and gene expression of eastern oysters in response to polyethylene terephthalate (PET) plastic exposure. Hatchery-produced larvae settled onto either oyster shell or PET plastic and metamorphosed into juveniles. One set of juvenile oysters was reared in an aquaculture facility for three months, and a second set was placed on natural reefs in the St. Mary's River of the Chesapeake Bay for ten months. Juvenile oysters grown on PET showed significantly higher mortality rates and reduced growth than those grown on shell after three months. After ten months of growth and maturation in natural waters, oysters grown on shell were 82% male while oysters grown on plastic had a significantly lower proportion of males (56% male). We measured differential gene expression of eight candidate genes involved in gametogenesis. In general, expression patterns followed expectations based on putative roles in either spermatogenesis or oogenesis. Exposure to plastic did not have a significant impact on gene expression. Small sample sizes limited statistical power to detect small effect sizes. Although not significant, females on plastic had higher median and mean expression than those on shell for all genes, except for the mean expression level of vitellogenin-6 (vit-6). Our findings suggest that plastic exposure alters the sex ratio of first-year oysters, resulting in more females than expected. Additional research into the expression of underlying genes that impact gamete differentiation and therefore sex determination is warranted.

塑料污染在海洋中无处不在，许多研究已经记录了纠缠、摄入或暴露于个别异种雌激素塑料添加剂的危险。海水中的塑料降解通过吸收有害有机污染物、释放构成塑料的复杂化学成分以及塑料碎片的碎片，构成了复杂的威胁。因此，需要一种更全面的方法来了解塑料暴露对海洋生物的影响。东部牡蛎（ Crassostrea virginica ）是西大西洋河口生态系统工程师的关键物种。个体每年都会经历配子发生并且能够从一年到下一年改变性别，通常是从男性到女性。年轻/较小的牡蛎主要是雄性和年长/较大的牡蛎主要是雌性，在种群水平上保持 1:1 的性别比例。作为无柄双壳类动物，牡蛎很容易受到沉积在海底的塑料的破坏性影响。本研究的目的是量化东部牡蛎在暴露于聚对苯二甲酸乙二醇酯(PET) 塑料后的存活率、生长、性别比例和基因表达方面的变化。孵化场生产的幼虫落在牡蛎壳或 PET 塑料上，然后变形成幼体。在水产养殖中饲养了一组幼年牡蛎三个月，第二套被放置在切萨皮克湾圣玛丽河的天然礁石上十个月。在 PET 上生长的幼牡蛎在三个月后显示出比在壳上生长的牡蛎显着更高的死亡率和生长速度。在自然水域中生长和成熟 10 个月后，带壳的牡蛎中有 82% 是雄性，而在塑料上生长的牡蛎的雄性比例明显较低（56% 是雄性）。我们测量了涉及配子发生的八个候选基因的差异基因表达。一般而言，表达模式遵循基于任一精子发生中推定作用的预期或卵子发生。接触塑料对基因表达没有显着影响。小样本量限制了检测小效应量的统计功效。尽管不显着，但对于所有基因，塑料上的雌性比壳上的雌性具有更高的中值和平均表达，除了 vitellogenin-6 ( vit-6)的平均表达水平。我们的研究结果表明，接触塑料会改变第一年牡蛎的性别比例，导致雌性比预期的多。需要进一步研究影响配子分化并因此影响性别决定的潜在基因的表达。