Benthic marine calcifiers coexist with CaCO 3 ‐undersaturated seawater worldwide

• Published in: Global biogeochemical cycles 2016-07, Vol.30 (7), p.1038-1053
• Main Authors: Lebrato, M., Andersson, A. J., Ries, J. B., Aronson, R. B., Lamare, M. D., Koeve, W., Oschlies, A., Iglesias‐Rodriguez, M. D., Thatje, S., Amsler, M., Vos, S. C., Jones, D. O. B., Ruhl, H. A., Gates, A. R., McClintock, J. B.
• Format: Article
• Language: English
• ISSN: 0886-6236; 1944-9224
• DOI: 10.1002/2015GB005260

Ocean acidification and decreasing seawater saturation state with respect to calcium carbonate (CaCO 3 ) minerals have raised concerns about the consequences to marine organisms that build CaCO 3 structures. A large proportion of benthic marine calcifiers incorporate Mg 2+ into their skeletons (Mg‐calcite), which, in general, reduces mineral stability. The relative vulnerability of some marine calcifiers to ocean acidification appears linked to the relative solubility of their shell or skeletal mineralogy, although some organisms have sophisticated mechanisms for constructing and maintaining their CaCO 3 structures causing deviation from this dependence. Nevertheless, few studies consider seawater saturation state with respect to the actual Mg‐calcite mineralogy (Ω Mg‐ x ) of a species when evaluating the effect of ocean acidification on that species. Here, a global dataset of skeletal mole % MgCO 3 of benthic calcifiers and in situ environmental conditions spanning a depth range of 0 m (subtidal/neritic) to 5600 m (abyssal) was assembled to calculate in situ Ω Mg‐ x . This analysis shows that 24% of the studied benthic calcifiers currently experience seawater mineral undersaturation (Ω Mg‐ x