Lipidomic alterations in oysters caused by environmentally relevant exposure to microplastics and estrogenic endocrine disrupting chemicals.

There is a ubiquitous co-occurrence of microplastics (MPs) and estrogenic endocrine disrupting chemicals (EEDCs) in aquatic environments. Their combined presence may induce sub-lethal stress in aquatic organisms, like molluscs, which may adapt to the stress through adjusting the lipidome. This study explored the individual and combined effects of polyethylene microplastics (PE-MPs) and a mixture of EEDCs at environmentally realistic concentrations on the lipidome of the Sydney rock oyster (Saccostrea glomerata). After seven days exposure, lipids were measured in the digestive glands and gonads using proton nuclear magnetic resonance (1H NMR) spectroscopy. Permutational analysis of variance (PERMANOVA) revealed the lipidome of oysters exhibited treatment differences with interactions between sex and tissue type. Subsequent post-hoc analysis revealed the male digestive gland to be significantly more responsive than the other tissues tested. An increase in cholesterols and aldehydes in all treatments compared to controls was ascribed to an adaptive response to transient oxidative stress in oysters, which was alleviated by increased food intake. There was a significantly greater effect of the EEDCs mixture than PE-MPs in oysters. The combined oxidative stress of PE-MPs and EEDCs from co-exposure did not exceed the individual effects of PE-MPs and EEDCs, which may relate to low exposure concentrations of PE-MPs, selective rejection of MPs in pseudofeces, or poor vector role of smooth surfaced PE-MPs.