Inhibition of photosynthetic CO2 fixation in the coral Pocillopora damicornis and its relationship to thermal bleaching

Publisher:
The Company of Biologists Ltd
Publication Type:
Journal Article
Citation:
Journal of Experimental Biology, 2014, 217 pp. 2150 - 2162
Issue Date:
2014-01
Full metadata record
Files in This Item:
Filename Description Size
Inhibition of photosynthetic CO2 fixation....pdfPublished Version1.44 MB
Adobe PDF
Two inhibitors of the CalvinBenson cycle [glycolaldehyde (GA) and potassium cyanide (KCN)] were used in cultured Symbiodinium cells and in nubbins of the coral Pocillopora damicornis to test the hypothesis that inhibition of the CalvinBenson cycle triggers coral bleaching. Inhibitor concentration range-finding trials aimed to determine the appropriate concentration to generate inhibition of the CalvinBenson cycle, but avoid other metabolic impacts to the symbiont and the animal host. Both 3 mmol l-1 GA and 20 µmol l-1 KCN caused minimal inhibition of host respiration, but did induce photosynthetic impairment, measured by a loss of photosystem II function and oxygen production. GA did not affect the severity of bleaching, nor induce bleaching in the absence of thermal stress, suggesting inhibition of the CalvinBenson cycle by GA does not initiate bleaching in P. damicornis. In contrast, KCN did activate a bleaching response through symbiont expulsion, which occurred in the presence and absence of thermal stress. While KCN is an inhibitor of the CalvinBenson cycle, it also promotes reactive oxygen species formation, and it is likely that this was the principal agent in the coral bleaching process. These findings do not support the hypothesis that temperature-induced inhibition of the CalvinBenson cycle alone induces coral bleaching.
Please use this identifier to cite or link to this item: