Oyster farming acts as a marine carbon dioxide removal (mCDR) hotspot for climate change mitigation.

Bivalve farming, a vital component of global aquaculture, has been proposed as a potential marine carbon dioxide removal (mCDR) strategy, yet its role remains contentious. Using field mesocosms, we demonstrate that oyster filter-feeding enhances mCDR by accelerating the formation of particulate and dissolved organic carbon in the water column and promoting organic carbon deposition in sediments. This process shifts the water column toward a more autotrophic and alkaline state, effectively sequestering CO2 from the atmosphere. Over the full culture period, the net carbon sequestered by oyster-driven organic carbon production is 2.39 times greater than the CO2 sequestered in oyster shells. These findings position oyster farming as a scalable, nature-based solution for climate change mitigation, offering dual benefits of carbon sequestration and enhanced food security. Our results underscore the potential of oyster farming to address global challenges such as rising food demand and ocean acidification, making it a critical component of sustainable marine resource management.