Chemical Toxicity of Robotic Hull In-Water Cleaning Wastewater on Embryonic Flounder

Abstract

In-water cleaning (IWC) involves the removal of biofilms and foulants from the hull of a ship using brushes or water jets. Several factors determine the potential for environmental harm associated with the release of chemical contaminants into the marine environment during IWC, which can create “hotspots” of contamination in coastal areas. To elucidate the potential toxic effects of IWC discharge, we investigated developmental toxicity in flounder embryos, which are sensitive to chemical contamination. Zinc and copper were the dominant metals, while copper pyrithione was the most abundant biocide associated with IWC discharge in two remotely operated IWC. Discharge from IWC carried by both remotely operated vehicles (ROVs) produced developmental malformations, including pericardial edema, spinal curvature, and tail-fin defects. We also analyzed the transcriptomic analysis to verify the potential effects of ROVs cleaning wastewater by Next-generation sequencing. The differentially expressed genes (DEGs) were identified in embryos exposed to cleaning wastewater from ROVs which is analyzed GO enrichment and gene regulatory analysis. In the network, TTN, MYOM1, CASP3, and CDH2 genes appeared to be key regulators of the toxic effects on muscle development. In embryos exposed to ROV B discharge, HSPG2, VEGFA, and TNF genes related to the nervous system pathway were affected. These results shed light on the potential impacts of muscle and nervous system development in nontarget coastal organisms exposed to contaminants found in IWC discharge.