Genomic-to-space measurements reveal large-scale ocean nutrient stress

Global ocean phytoplankton growth and primary production are intimately linked to nutrient fluctuations from seasonal to millennial time scales. Rapid recycling compromises the utility of surface nutrient or phytoplankton stocks for delineating the biogeography of global ocean nutrient stress. Here, field-measured hydrography and ‘omics biomarkers of nutritional status are coupled to a satellite remote sensing metric of cell physiology to mechanistically evaluate monthly to multi-decadal shifts in global phytoplankton nutrient stress. We observe a clear biogeography in nutrient stress aligned with variations in the nutricline depth and distinctly elevated stress in nitrogen- compared to phosphate-limited waters. Regions where cells are switching to rare forms of alternative nutrients are most stressed. Temporal modes of stress are dominated by seasonal changes, but strong signatures of natural climate cycles are also apparent. Surface ocean warming over the last twenty years has led to broad increases in nutrient stress with one notable exception. Southern hemisphere oligotrophic regions experienced declines in nutrient stress that we attribute to changes in ocean nitrogen fixation. Our integrated hydrography, genomic, and satellite remote sensing of phytoplankton physiology has uncovered contemporary changes in global phytoplankton nutrient stress.