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Transient Copper Exposure During Embryogenesis and Temperature Affect Developmental Rate, Survival, and Fin Regeneration in Japanese Medaka (Oryzias latipes)

Combined environmental stressors that an organism experiences can have both immediate and lasting consequences. In the present study, we exposed Japanese medaka (Oryzias latipes) embryos to sublethal copper sulfate (CuSO4; 0, 10, and 100 ppb) in combination with different rearing temperatures (27, 30, and 33 °C) to assess acute and latent effects on development, growth, and regenerative capacity. Embryos exposed to CuSO4 and/or higher temperatures hatched significantly earlier. At 4 months post‐exposure, fish exposed to low levels of CuSO4 during development had higher survival, whereas fish exposed to both 100 ppb CuSO4 and 33 °C temperatures had significantly lower survival. In addition, a sex‐specific effect of embryonic CuSO4 exposure was observed as female mass decreased with increasing Cu dose. We also assessed caudal fin regenerative capabilities in both embryo‐exposed fish at 4 months of age and adult medaka that were exposed to 0, 10, and 100 ppb CuSO4 at room temperature during a 14‐day trial. Whereas fin regeneration was unaffected by adult exposure to Cu, fish transiently exposed during embryogenesis displayed an initial increase in fin growth rate and an increased incidence of abnormal fin morphology following regrowth. Collectively, these data suggest that developmental Cu exposure has the potential to exert long‐lasting impacts to organismal growth, survival, and function. Environ Toxicol Chem 2022;41:748–757. © 2021 SETAC