%0 journal article
%@ 2375-2548
%A Van Dam, B., Zeller, M., Lopes, C., Smyth, A., Böttcher, M., Osburn, C., Zimmerman, T., Pröfrock, D., Fourqurean, J., Thomas, H.

%D 2021
%J Science Advances
%N 51
%P eabj1372 
%R doi:10.1126/sciadv.abj1372
%T Calcification-driven CO2 emissions exceed “Blue Carbon” sequestration in a carbonate seagrass meadow
%U https://doi.org/10.1126/sciadv.abj1372
51 
%X Long-term “Blue Carbon” burial in seagrass meadows is complicated by other carbon and alkalinity exchanges that shape net carbon sequestration. We measured a suite of such processes, including denitrification, sulfur, and inorganic carbon cycling, and assessed their impact on air-water CO2 exchange in a typical seagrass meadow underlain by carbonate sediments. Eddy covariance measurements reveal a consistent source of CO2 to the atmosphere at an average rate of 610 ± 990 μmol m−2 hour−1 during our study and 700 ± 660 μmol m−2 hour−1 (6.1 mol m−2 year−1) over an annual cycle. Net alkalinity consumption by ecosystem calcification explains >95% of the observed CO2 emissions, far exceeding organic carbon burial and anaerobic alkalinity generation. We argue that the net carbon sequestration potential of seagrass meadows may be overestimated if calcification-induced CO2 emissions are not accounted for, especially in regions where calcification rates exceed net primary production and burial.