Climate change alters biogeochemical cycles in oxygen-depleted and dead zones

Marine oxygen deficient and dead zones are economically and ecologically important regions with unique impacts on marine nutrient cycling and biogeochemistry. Climatic impact-drivers expected to affect oxygen deficient zones and associated nutrient cycles include changes in temperature, wind speed, and atmospheric depositions. These climatic impact-drivers will increase sea surface temperatures that reduce oxygen solubility, increase stratification and respiration, as well as induce changes in circulation that intensify upwelling and regulate the production and emission of greenhouse gases to the atmosphere. Deoxygenation will impact biogeochemical cycles of nitrogen, phosphorus, and silicon. Climatic changes are likely to decrease bioavailable nitrogen and enhance sedimentary phosphorus remobilization, altering water column nutrient stoichiometry. Expansion of oxygen deficient zones can also have negative socio-economic and ecological consequences. Future research should focus on experimental and mesocosm studies, examine the responses of microbial communities, improve biogeochemical and ocean circulation models, and build and expand monitoring programs.