Award: OCE-1436326

Oceanic oxygen concentrations are key to life in the ocean and societal food and economic resources are closely linked to ocean oxygen levels. When oxygen levels in the ocean get too low, consequences include the drastic reorganization of the food web and a significant change in ocean chemistry. Ask any fisherman, they will tell you how oxygen levels impact the fish or seafood they catch, where they catch it, and how much they catch! Our work set about to design and test measurements of very obscure isotopes of oxygen to see if these very rare atoms, mixed in with all the ?normal? oxygen atoms, might tell us about how the ocean was obtaining and losing oxygen. We use these rare isotopes as ?tracers?, much like the dye one can imagine as a useful way to trace water movement. To do this work successfully, we need to make measurements at various ocean locations and various depths. We focused on waters adjacent to Los Angeles, largely because these waters change their oxygen content regularly. We also made these measurements on a ship traveling from Hawaii to Alaska. The results are significant and it looks like we are going to be able to use these rare oxygen isotopes as tracers! We will be able to map out how and where the ocean ?inhales? and ?exhales?. Another reason our work has great societal relevance is because as CO2 builds up in our atmosphere, ocean water pH gets more and more acidic. Oxygen levels declining can exacerbate this increasing acidity. Hence, studying an increasingly acidic ocean hand in hand with ocean oxygen levels is very important to keep track of how the ocean is dealing with global changes. Who cares? The organisms that live in the ocean that produce shells of calcium carbonate (gastropods, tiny plants, tiny shelled consumers)---they care. As the ocean becomes more acidic, these shells dissolve. Many of these organisms cannot live without shells. The whole-ocean food web is impacted. Last Modified: 01/03/2018 Submitted by: William M Berelson