Ocean Acidification

Phosphorus (P) availability constrains marine productivity, yet how ocean acidification interacts with intensifying phosphate limitation remains unresolved. Here we present multi-omics analyses of >1,000 generations of experimental diatom evolution to disentangle evolutionary and acclimation-driven responses to ocean acidification under different phosphate regimes. Long-term selection under elevated CO₂ produced heritable increases in growth and carbon fixation that persisted irrespective of phosphate availability. In contrast, ocean acidification-driven reductions in particulate organic phosphorus were reversed after reciprocal transfers between selection treatments under phosphate limitation, indicating acclimation and environment-dependent P allocation. Multi-omics analyses indicate that the particulate organic phosphorus decline could be attributed to depletion of cellular P reserves and enrichment of non-P cell membrane lipids under combined ocean acidification and phosphate stress. Coastal mesocosm experiments revealed similarly reduced particulate organic phosphorus in natural phytoplankton at low-phosphate stations under ocean acidification. Global meta-transcriptomes further indicate widespread upregulation of gene expression in non-P cell membrane lipid pathways in high-pCO₂ and low-phosphate regions. Earth system models predict a 211% to 2,185% decline in particulate organic phosphorus by 2100 under the under the Shared Socioeconomic Pathway (SSP)2–4.5 or SSP5–8.5 scenarios, respectively. These results show that ocean acidification could intensify nutrient imbalance and reshape global phosphorus cycling in marine ecosystems.

Wang B., Wang Y., Sun Y., Huang X., Yang F., Wang Z., Chi H., Tong S., Fan X., Zhang X., Sun K., Fu F., Wang Y., Hutchins D. A., Chen G., Xu D. & Ye N., 2026. Ocean acidification reshapes phytoplankton phosphorus metabolism under phosphate-limited conditions. Nature Geoscience 19: 1339-1346. Article.