Acute toxic effects and transcriptomic changes of in-water cleaning (IWC) discharge on juvenile Rockfish (Sebastes schlegelii)

Abstract

Introduction

During hull in-water cleaning (IWC) 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 [1]. 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.

Results and Discussion In this study, we evaluate the toxic effects of IWC discharge on juvenile rockfish (Sebastes schlegelii) which is one of major fishery resources. IWC discharge was sampled at 10-, 100-, and 1000-fold dilutions and exposed for 7 days. No lethal toxicity was observed during the acute toxic experiment (7 days) in control and exposure groups. In the study, high proportions of zinc were found in the IWC discharge, which was believed to have affected the health of the exposed organisms. Significantly increased enzyme activities were observed, but no enzyme activity trend could be identified with respect to IWC discharge exposure. In addition, IWC discharge also affected the expression genes related to oxidative stress, detoxification, and the immune systems. Transcriptome analysis in the brain and liver revealed that the genes associated with response to chemical, detoxification, metabolic processes, and immune system were differentially expressed. These results demonstrated the need for proper management of IWC discharge in the coastal environment.

References [1] Thomas, K.V., McHugh, M., Waldock, M., 2002. Antifouling paint booster biocides in UK coastal waters: inputs, occurrence and environmental fate. Sci. Total Environ. 293. 117-127.

*Corresponding author: jungjh@kiost.ac.kr