Acute toxic effects and mechanism of antifouling paint particles on juvenile Rockfish

Abstract

During hull-cleaning process, the antifouling paint particle produced is often directly discharged into coastal seawater and coastal sediment. Chemical component analysis of hull cleaning wastewater has shown that up to 75% of the biocide present is related to paint particles, which can potentially account for between 6 and 17% of the daily biocide input into a marina (Thomas et al., 2002). Therefore, antifouling paint particles (APPs) have been spotlighted as a source of metal contamination in coastal sediments, potentially leaching large amounts of copper and zinc into costal aquatic environments. However, there have been few studies assessing the toxic effects of more complex antifouling system mixtures (such as combinations of heavy metals and biocides) on fishery resources. In the study, we evaluate the toxic effects of antifouling paint particles on juvenile rockfish (Sebastes schlegelii) which is one of major fishery resources. Paint particle was sampled from dry dock hull cleaning wastewater and 10-, 100-, and 1000-fold dilutions were exposed for 7 days. Zinc was identified to be the major contaminant with the highest concentration in the wastewater. No lethal toxicity was observed during the acute toxic experiment (7 days) in control and exposure groups. GST (glutathione-S-transferase) and SOD (superoxide dismutase) tended to increases at high concentrations. Hepatic ROS (reactive oxygen species) and brain AChE (acetylcholinesterase) activities was increase after exposure to antifouling paint particles. The gene of metallothionine was highly expressed in fish exposed to the paint particle. Some of immune-related genes including the G-CSF (granulocyte colony-stimulating factor), ISG15 (Interferon-stimulated gene 15), GST, and NF-kB (nuclear factor Kappa-B) were also increased in fish exposed to antifouling paint particles at 24 h than those of the control group fish. Transcriptome analysis in the brain and liver revealed that the genes associated with metabolism, signaling interaction, and the immune system were significantly variated. Moreover, genes encoding proteins, such as vitellogenin and neuropeptide, were among the top most differentially expressed genes. These results demonstrate the need for proper management to antifouling paint particles contamination in coastal environment.