Benthic marine calcifiers coexist with CaCO sub(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, MD, Koeve, W, Oschlies, A, Iglesias-Rodriguez, MD, Thatje, S, Amsler, M, Vos, S C, Jones, DOB, Ruhl, HA, Gates, A R, McClintock, J B
• Format: Article
• Language: English
• Subjects: Brackish; Marine
• ISSN: 0886-6236; 1944-9224
• DOI: 10.1002/2015GB005260

Ocean acidification and decreasing seawater saturation state with respect to calcium carbonate (CaCO sub(3)) minerals have raised concerns about the consequences to marine organisms that build CaCO sub(3) structures. A large proportion of benthic marine calcifiers incorporate Mg super(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 sub(3) structures causing deviation from this dependence. Nevertheless, few studies consider seawater saturation state with respect to the actual Mg-calcite mineralogy ( Omega sub(Mg-)x) of a species when evaluating the effect of ocean acidification on that species. Here, a global dataset of skeletal mole % MgCO sub(3) of benthic calcifiers and in situ environmental conditions spanning a depth range of 0m (subtidal/neritic) to 5600m (abyssal) was assembled to calculate in situ Omega sub(Mg-)x. This analysis shows that 24% of the studied benthic calcifiers currently experience seawater mineral undersaturation ( Omega sub(Mg-)x