Acute and chronic effects of polymetallic nodule leachate in the marine copepod Tigriopus koreanus

Polymetallic nodules containing manganese, iron, and other metals are found in the seafloor. Leachates of polymetallic nodules can be discharged into seawater during ocean mining, disrupting marine ecosystems and causing adverse effects on marine organisms. Here, we investigate the acute and chronic effects of two polymetallic nodule leachates on the life-history parameters (mortality, development, and fecundity) and transcriptional differences of detoxification, antioxidant, and reproduction-related genes for cytochrome P450, glutathione S-transferase, and vitellogenin in the marine copepod Tigriopus koreanus. We also examine single and combined effects for six metals whose concentrations differ between the two leachates. No significant changes in mortality were observed, but developmental time was significantly shortened and fecundity increased in T. koreanus in response to exposure to the leachates. No adverse effects on physiological parameters were seen, but transcriptional differences by leachates were evident. In addition, manganese and iron in the leachates improved copepod development when they were combined with other metals. The findings of this study elucidate the potential impact of polymetallic nodule leachates on marine copepods.