Emergent properties of branching morphologies modulate the sensitivity of coral calcification to high PCO2 [RESEARCH ARTICLE]

Peter J. Edmunds and Scott C. Burgess Experiments with coral fragments (i.e., nubbins) have shown that net calcification is depressed by elevated PCO2. Evaluating the implications of this finding requires scaling of results from nubbins to colonies, yet the experiments to codify this process have not been completed. Building from our previous research demonstrating that net calcification of Pocillopora verrucosa (2–13 cm diameter) was unaffected by PCO2 (400 µtam and 1,000 µatm) and temperature (26.5°C and 29.7°C) we sought generality to this outcome by testing how colony size modulates PCO2 and temperature sensitivity in a branching acroporid. Together these taxa represent two of the dominant lineages of branching corals on Indo-Pacific coral reefs. Two trials conducted over two years tested the hypothesis that the seasonal range in seawater temperature (26.5°C and 29.2°C) and a future PCO2 (1,062 µatm versus an ambient of 461 µatm) affect net calcification of an ecologically relevant size range (5–20 cm diameter) of colonies of Acropora hyacinthus. Like P. verrucosa, the effects of temperature and PCO2 on net calcification (mg d–1) of A. verrucosa were not statistically detectable. These results support the generality of a null outcome on net calcification of exposing intact colonies of branching corals to environmental conditions contrasting seasonal variation in temperature and predicted future variation in PCO2. W...
Source: Journal of Experimental Biology - Category: Biology Authors: Tags: RESEARCH ARTICLE Source Type: research