Metagenomic analysis reveals global-scale patterns of ocean nutrient limitation

Nutrient supply regulates the activity of phytoplankton, but the global biogeography of nutrient limitation and co-limitation is poorly understood. Prochlorococcus adapt to local environments by gene gains and losses, and we used genomic changes as an indicator of adaptation to nutrient stress. We collected metagenomes from all major ocean regions as part of the Global Ocean Ship-based Hydrographic Investigations Program (Bio-GO-SHIP) and quantified shifts in genes involved in nitrogen, phosphorus, and iron assimilation. We found regional transitions in stress type and severity as well as widespread co-stress. Prochlorococcus stress genes, bottle experiments, and Earth system model predictions were correlated. We propose that the biogeography of multinutrient stress is stoichiometrically linked by controls on nitrogen fixation. Our omics-based description of phytoplankton resource use provides a nuanced and highly resolved description of nutrient stress in the global ocean.

Automated summary

Nutrient supply affects phytoplankton activity, but understanding of global nutrient limitation and co-limitation is limited. Prochlorococcus adapt to local environments through gene gains and losses, with genomic changes indicating adaptation to nutrient stress. Regional transitions in stress type and severity, as well as widespread co-stress, were found, with correlations between Prochlorococcus stress genes, bottle experiments, and Earth system model predictions. The biogeography of multinutrient stress is linked through controls on nitrogen fixation, providing a detailed description of nutrient stress in the global ocean based on omics data.