How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Young Corals
Mumby, P.J.  1999.  Bleaching and hurricane disturbances to populations of coral recruits in Belize.  Marine Ecology Progress Series 190: 27-35.

What was done
From September to December 1998, corals in Belize experienced, in the words of the author, "two of the most severe disturbances of recent decades: massive coral bleaching and Hurricane Mitch."  Hence, having surveyed juvenile recruits just before these two events, Mumby went back just afterwards to determine how they fared.  The significance of his work is indicated by his statement that "this is the first study (to the best of my knowledge) to show the direct effects of a severe bleaching event on the population dynamics of juvenile corals."

What was learned
Although 70 to 90% of adult coral colonies were severely bleached, only 25% of coral recruits exhibited signs of bleaching during the event.  In addition, one month after the event, it was concluded that "net bleaching-induced mortality of coral recruits ? was insignificant."

What it means
"Surprisingly," as the author states, "coral bleaching alone had no measurable effect on either recruit density or community structure."  That word surprising is very significant, for in our editorial Back from the Dead: Coral Recovery Signals Resiliency of Reef Ecosystems, we report on some other cases of surprising coral recoveries from "the most extensive coral bleaching event ever seen."

The reason these recoveries are surprising, of course, is merely because we have not previously know of this ability of juvenile corals to successfully weather such bleaching events.  Now we do know something of this ability, although we have only scratched the surface of what remains to be learned in this regard.  Nevertheless, what we have learned suggests that we should never sell nature short.  She has surprising ways of proving us wrong.

Reviewed 6 September 2000