Context-Driven Carbon Storage Potential in Oyster Reef Restoration: Insights for Ecosystem Management and Conservation

Carbon sequestration is increasingly recognized as an essential service provided by vulnerable vegetated coastal habitats, and emerging evidence suggests that oyster reefs, like vegetated habitats, may also play a vital role in capturing and storing carbon. However, there is high variability in carbon storage estimates across the relatively few studies conducted and oyster reefs—like vegetated habitats—have sustained significant global losses. Increased awareness of oyster reef loss coupled with an emerging interest in oyster reefs as potential carbon sinks has necessitated a greater understanding of oyster reefs’ role in the carbon cycle, the extent by which oyster reefs can store carbon, and how carbon dynamics may change depending on environmental conditions. Therefore, understanding where restored oyster reefs can best enhance carbon sequestration is critical to maximizing their potential ecosystem services. This study examines the carbon budget of natural and restored oyster reefs in St. Charles Bay, Texas, focusing on how adjacent habitat, reef age, and depth influence carbon storage rates and long-term storage potential.

Sampling involved vibracoring through oyster reefs to collect marine sediment and shell samples for carbon budget assessment. The vibracoring technique uses high-frequency, low-amplitude vibrations to drive an aluminum pipe vertically through the reef, obtaining intact cores for analysis of organic and inorganic carbon. To evaluate the capacity of natural reefs for long-term carbon burial, the organic and inorganic carbon content in each core is scaled to the age of each reef on a per-square-meter basis. Reef age is estimated by radiocarbon dating a subsample of coupled oyster shells from the base of natural reefs. Initial results reveal that restored subtidal reefs generally function as carbon sinks, exhibiting increased sediment chlorophyll a, organic matter, and a shift toward finer sediment composition post-restoration. In natural intertidal reefs, those near vegetated habitats store notably more organic carbon than isolated reefs. The consistent presence of both organic and inorganic carbon throughout these natural reef cores underscores the potential of oyster reefs for long-term carbon storage.

These findings highlight the importance of careful site selection and habitat context in maximizing the ecological benefits of oyster reef restoration efforts. By understanding how reefs contribute to carbon capture and long-term storage, this research provides essential insights for optimizing restoration strategies to enhance carbon storage potential. Moreover, these results support the development of area-based management approaches aligned with global biodiversity and climate goals, making oyster reef restoration a key component of sustainable coastal management and climate-smart conservation planning.