Harnessing nature's buffer: Assessing the role of bivalve shells in coastal alkalinity regeneration

Abstract

Bivalve shells, a natural alkaline material, play a crucial role in coastal carbon cycles by influencing total alkalinity (TA) and dissolved inorganic carbon (DIC). This study investigated oyster shell dissolution in Narragansett Bay, Rhode Island, under varying pCO2 conditions, revealing TA regeneration rates of 4–56 μmol L−1 d−1, which could mitigate localized ocean acidification (OA). Notably, significant dissolution occurred even in oversaturated waters (Ωcalcite > 1) due to corrosive microenvironments created by microbial respiration. Although shell formation (calcification) emits CO2, TA regeneration (shell dissolution) buffers OA when the carbonate chemistry of the water is corrosive, offsetting the initial CO2 emissions. Therefore, recycling shells enhances ecosystem resilience by buffering acidification stress for OA‐sensitive organisms. This research highlights the need to revisit shell management policies to promote sustainable aquaculture and sheds light on the potential of incorporating this nature‐based alkaline material into ocean alkalinity enhancement strategies for improved coastal carbon management.