Award: OCE-1433719

Ocean deoxygenation is the next major marine environmental challenge for both scientific community and policy makers, after warming and ocean acidification. The impact of deoxygenation on marine life is not easy to predict. It is critical to establish the baseline ecological and physiological response to oxygenation. Otolith chemistry can contribute great amount of information on this topic. Mn/Ca has been the go-to hypoxia proxy in otolith, however, not all Mn/Ca data are uniquely tied to oxygen changes. The lack of independent oxygen proxy to compare with Mn/Ca is an urgent issue to address. Otolith I/Ca fits such a need. Our leaching experiment show majority of the iodine are associated with organic matter within the otolith. I/Ca most often peaks up in the core region. Empirically, we often observe an inverse correlation between I/Ca and Mn/Ca, demonstrating the potential of using I/Ca as an independent confirmation of oxygen conditions indicated by Mn/Ca. This inverse correlation does not always exist in each individual otolith. It is potentially a great opportunity if we want to further test any false positive or false negative of hypoxia episodes, indicated by different redox proxies. We observed long-term trends in I/Ca from the Stone Age to modern ocean. Last Modified: 11/06/2018 Submitted by: Zunli Lu