Detrimental effects of hull-cleaning wastewater on embryo development via oxidative stress induction in the Java medaka Oryzias javanicus

Considerable amounts of paint particles and debris are released into coastal areas during the physical cleaning of ship hulls. However, there is a paucity of data regarding their potential toxic impacts on non-target aquatic organisms. Therefore, we undertook a thorough evaluation encompassing acute survival effects and developmental parameters of Java medaka Oryzias javanicus embryos exposed to filtered wastewater, alongside the assessment of alterations in antioxidant constituents.

Embryos were subjected to different concentrations of filtered wastewater (up to 1%) subsequent to fertilization. Analysis encompassed the examination of embryo and hatched larvae survival rates, time taken for hatching, and developmental parameters, coupled with biochemical assessments of oxidative stress and DNA damage markers.

Dose-dependent mortality, hatching delays, and developmental abnormalities were observed in embryos. Concurrently, there were notable increases in intracellular reactive oxygen species and malondialdehyde levels, accompanied by elevated enzymatic activities of glutathione S-transferase, glutathione peroxidase, catalase, and superoxide dismutase. In addition, DNA damage was observed at the highest concentration (1%) of wastewater treated in this study.

The observed changes in in vivo parameters and biochemical constituents indicate that sublethal concentrations of hull-cleaning wastewater exerted a toxic influence on Java medaka embryos.