Patrick Downes, Leigh Marsh, Joaquim Bento, Alexander Webber, Michael Clarke

There is an overwhelming consensus between researchers based on a vast body of peer-reviewed literature that deep sea ecosystems constitute an oxygen sink. Specific studies on abyssal seafloor regions that contain polymetallic nodules have also confirmed this result. In contrast to this well-founded and longstanding paradigm, Sweetman et al. claim to provide evidence to support a hypothesis that polymetallic nodules abiotically produce oxygen in the deep sea. In response, we critique the methodology that the authors outline and present previously non-disclosed data and metadata directly related to the experiments they present. Furthermore, we highlight previously published data that Sweetman et al. include without citation and critical metadata that they omit. The data and metadata that Sweetman et al. omit significantly alters how one interprets the results and directly undermines their claims. Given these revelations, we suggest that the hypothesis that polymetallic nodules produce oxygen can be wholly rejected.