Shellfish Aquaculture Complements Nutrient Reduction in Mitigating Climate-Exacerbated Coastal Hypoxia.

Coastal hypoxia, driven by human-induced nutrient enrichment and global warming, significantly threatens marine ecosystems. While cutting land-derived nutrient sources has been proposed as the key solution, its effectiveness may be undermined by climate change, and costs may rise after addressing the easier targets. Evaluating various nutrient measures under future climate scenarios is critical but challenging due to inadequate projections for coastal processes. In this global context, we combine field measurements with a coast-resolved physical-biogeochemical model to assess the effectiveness of land-based and alternative mitigation strategies under near-term (2016-2045) and long-term (2071-2100) climate change scenarios in a representative estuary-shelf system. Our findings evidence that stringent land-based nutrient reduction is necessary but insufficient to halt deoxygenation under climate change. This insufficiency is mainly due to enhanced water-column stratification, driven by climate warming and its associated increase in river discharge, which restricts oxygen replenishment more than the reductions in biogeochemical oxygen consumption achieved through nutrient management. We demonstrate that oyster aquaculture can serve as an effective complementary strategy to remove nutrients and combat oxygen depletion. This incentivizing approach aligns with the global trend of increasing nonfed aquaculture, offering a promising supplementary solution to the challenges of managing coastal nutrients and mitigating hypoxia globally.