Project: Calcification in low saturation seawater: What can we learn from organisms in the proximity of low pH; undersaturated submarine springs

NSF Abstract:
To date scientists have primarily used short-term single species experiments to study responses of organisms to increased pCO2. While these experiments are important, they represent an artificial situation, being isolated from many of the biological interactions. Moreover, these experiments do not truly reflect the effects on organisms over longer timescales in actual field situations.

In this study, researchers at the University of California at Santa Cruz will assess the utility of low pH submarine springs as field study sites for investigating calcification at low aragonite saturation. It has been reported that many reef-building corals cease calcification at saturation as high as 2.0; around these springs calcifying corals inhibit waters well below this value. Work will take place at a series of springs in Mexico where discharging water pH ranges from 8.07 to 7.25 and saturation from less than 0.5 to 5. While these springs are by no means analogs for future ocean calcification they can still provide a natural laboratory to study controls on coral calcification. Field observations are usually confounded by the presence of many potentially important variables in addition to saturation. Moreover, it is not trivial to quantify the natural spatial and temporal variability of the parameters of interest. Thus it is not clear how useful this setting might be for conducting extensive field based calcification research (high risk). Accordingly, the research team will conduct field surveys to map the chemical and physical characteristics of the water around the springs (and corals) and describe population and community patterns along the saturation gradient. They will install probes to capture the temporal and spatial variability. These observations should allow assessment of the site's utility for researching processes that sustain calcification at low saturation and for future manipulative experiments.

Background publications:
Crook ED, Potts D, Rebolledo-Vieyra M, Hernandez L, Paytan A. 2011. Calcifying coral abundance near low pH springs: implications for future ocean acidification. Coral Reefs, 31(1): 239-245.
Paytan A, Crook ED, Cohen AL, Martz T, Takeshita Y et al. 2014. Reply to Iglesias-Prieto et al.: Combined field and laboratory approaches for the study of coral calcification. Proc Natl Acad Sci USA, 111 (3): E302-E303.
Crook ED, Cohen AL, Rebolledo-Veiyra M, Hernandez L, Paytan A. 2013. Reduced calcification and lack of acclimatization by coral colonies growing in areas of persistent natural acidification. Proc Natl Acad Sci USA, 110 (27): 1044-1049.