Acute disturbance, but chronic re-equilibration of the oyster metabolome to 17β-estradiol and nonylphenol exposure

In estuaries, aquatic organisms are often exposed to estrogenic endocrine disrupting chemicals (EEDCs), including 17β-estradiol (E2) and nonylphenol (NP), which affect physiology and metabolism. This study evaluated metabolic profiles of Sydney rock oysters (Saccostrea glomerata) using ¹HNMR -based metabolomics after acute (14 days), pulse (14 days exposure followed by 14 days depuration), and chronic (28 days) exposure of E2 at 200 ng/L and NP at 5000 ng/L. Only acute exposure to both E2 and NP led to marked metabolic perturbations. Energy and stress-related metabolites including adenosine monophosphate, succinate, acetoacetate, and glutamate significantly increased in acute treatments compared to controls, suggesting heightened energy demand to cope with oxidative and osmotic stress. However, the metabolites from pulse and chronic exposure treatments were not significantly different from the control. Such responses highlight a time-dependent adaptation of molluscs, similar to depuration. E2 is expected to be more rapidly metabolised in molluscs than NP, leading to comparatively slower metabolic adaptation of molluscs to NP exposure. Finally, this study emphasizes that oysters have a time-dependent adaptive mechanism to cope with EEDC exposure.