MCR LTER: Coral Reef: Porites growth, respiration, and photophysiology data in support of Edmunds 2012 Marine Biology, v159, 2149-2160

These data were generated from a one-time experiment in support of a coral
ecophysiology manuscript; published in Marine Biology. Edmunds (2012) Marine Biology
159: 2149-2160 doi:10.1007/s00227-012-2001-y The hypothesis that was tested stated that high pCO 2 (76.6 Pa and 87.2 Pa vs. 42.9 Pa) has no effect
on the metabolism of juvenile massive Porites spp. after 11 days at 28 °C and 545 lmol
quanta m-2 s-1. The response was assessed as aerobic dark respiration, skeletal weight
(i.e., calcification), biomass, and chlorophyll fluorescence. Corals were collected from
the shallow (3–4 m) back reef of Moorea, French Polynesia (17°28.6140 S, 149°48.9170 W),
and experiments conducted during April and May 2011. An increase in pCO 2 to 76.6 Pa had no
effect on any dependent variable, but 87.2 Pa pCO 2 reduced area-normalized (but not
biomass-normalized) respiration 36 %, as well as maximum photochemical efficiency (Fv/Fm)
of open RCIIs and effective photochemical efficiency of RCIIs in actinic light (DF/Fm0 );
neither biomass, calcification, nor the energy expenditure coincident with calcification
(J g-1) was effected. These results do not support the hypothesis that high pCO 2 reduces
coral calcification through increased metabolic costs and, instead, suggest that high pCO 2 causes metabolic depression and photochemical impairment similar to that associated with
bleaching. Evidence of a pCO 2 threshold between 76.6 and 87.2 Pa for inhibitory effects
on respiration and photochemistry deserves further attention as it might signal the
presence of unpredictable effects of rising pCO 2 .