MCR LTER: Coral Reef: Coral Growth in Temperature and Alkalinity Treatments: Edmunds 2011 Limnology & Oceanography

These data were generated from a one-time experiment in support of a coral ecophysiology manuscript;
published in Edmunds, PJ (2011) Limnology and Oceanography 56: 2402-2410
doi: 10.4319/lo.2011.56.6.2402 I tested the hypothesis that the effects of high pCO 2 and temperature on massive Porites spp. (Scleractinia) are
modified by heterotrophic feeding (zooplanktivory). Small colonies of massive Porites spp. from the back reef of
Moorea, French Polynesia, were incubated for 1 month under combinations of temperature (29.3 C vs. 25.6 C),
pCO 2 (41.6 vs. 81.5 Pa), and feeding regimes (none vs. ad libitum access to live Artemia spp.), with the response
assessed using calcification and biomass. Area-normalized calcification was unaffected by pCO 2 , temperature,
and the interaction between the two, although it increased 40% with feeding. Biomass increased 35% with feeding
and tended to be higher at 25.6 C compared to 29.3 C, and as a result, biomass-normalized calcification
statistically was unaffected by feeding, but was depressed 12-17% by high pCO 2 , with the effect accentuated at
25.6 C. These results show that massive Porites spp. has the capacity to resist the effects on calcification of
1 month exposure to 81.5 Pa pCO 2 through heterotrophy and changes in biomass. Area-normalized calcification
is sustained at high pCO 2 by a greater biomass with a reduced biomass-normalized rate of calcification. This
mechanism may play a role in determining the extent to which corals can resist the long-term effects of ocean
acidification.