Before revision: Mitigation of environmental impacts There is still a gap in research of how to reduce these environmental impacts.
After revision: Reduced oxygen contentStudies have shown that the nodules are important for the production of "dark oxygen", oxygen produced without light, which provide the seafloor in the deep ocean with much of its oxygen.Discovery of 'dark oxygen' from deep-sea metal lumps could trigger rethink of origins of lifeMitigation of environmental impacts There is still a gap in research of how to reduce these environmental impacts.