How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Coral Adaptation to Solar-Induced Bleaching?
Brown, B.E., Ambarsari, I., Warner, M.E., Fitt, W.K., Dunne, R.P., Gibb, S.W. and Cummings, D.G.  1999.  Diurnal changes in photochemical efficiency and xanthophyll concentrations in shallow water reef corals: Evidence for photoinhibition and photoprotection.  Coral Reefs 18: 99-105.

What was done
The authors examined the photosynthetic efficiency and potential for regulation of photosynthesis in seven species of shallow water reef corals at Phuket Marine Biological Center, Thailand in 1997 and 1998.

What was learned
Studies of corals exposed to higher-than-normal solar irradiance revealed the presence of certain photoprotective proteins that reduce solar-induced tissue damage or bleaching.  Analysis of corals in 1997 revealed a higher concentration of photoprotective proteins in west facing corals as opposed to east facing corals, suggesting "an improved photoprotective ability in the west facing coral surface as a result of acclimatization to the higher incident irradiance normally experienced by this side of the coral colony in the field."  In 1998, however, following a severe bleaching episode that took place after the 1997 measurements, "there were no differences between the east and west [coral] cores at any time during the experiments."

What it means
Because the difference in the proportion of photoprotective proteins that existed between the east and west facing corals diminished after a severe solar-induced bleaching episode, the authors concluded that irradiance history is probably an important factor governing the proteins' ability to protect corals from photodamage.  They further speculate that "acclimatization to high PAR, by stimulating photoprotective mechanisms ? might in turn reduce the susceptibility of corals to bleaching from the combined effects of irradiance and elevated seawater temperatures."

Reviewed 15 September 1999