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HighlandReefer
10/02/2009, 02:45 PM
The interaction of ocean acidification and
carbonate chemistry on coral reef
calcification: evaluating the carbonate
chemistry Coral Reef Ecosystem
Feedback (CREF) hypothesis on the
Bermuda coral reef
http://www.biogeosciences-discuss.net/6/7627/2009/bgd-6-7627-2009.pdf

From this article Published 28 July 2009:

"Conclusions

In our study, we show that rates of coral calcification were closely coupled with carbonate
chemistry [CO2− 3 ] and Ňaragonite, in the natural environment, rather than other
environmental factors such as light and temperature. Our field observations provide
15 sufficient data to hypothesize that there is a seasonal carbonate chemistry coral reef
ecosystem feedback (i.e. CREF hypothesis) between the primary components of the
reef ecosystem (scleractinian hard corals and macroalgae) and carbonate chemistry. It
is also likely that this seasonal phenomenon is present in other tropical reefs although
attenuated compared to high-latitude reefs such as Bermuda. Furthermore, due to
lower annual mean surface seawater [CO2− 3 20 ] and Ňaragonite in Bermuda compared to
more tropical regions, Bermuda coral will likely experience seasonal periods of zero
NEC within a decade in response to future acidification of the oceans. It appears that
the entire reef may already be experiencing periods of zero NEC during the wintertime,
resulting in a transition to net decalcification (i.e. net dissolution over calcification). As
25 such, the Bermuda coral reef appears to be one of the first responders to the negative
impacts of ocean acidification among tropical and subtropical reefs. Furthermore, we
anticipate that the Bermuda coral reef (as well as other high latitude reefs) will likely be
subjected to “seasonal decalcification” with wintertime decalcification occuring many
decades before summertime decalcification. Thus, on societally relevant time-scales,
we expect that the Bermuda reef will endure an extended transition to decalcified conditions
over a period of decades rather than a short transition at sharply-defined critical
5 thresholds in tropical coral reef counterparts.