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Corals Adapt to Bleaching
Kumaraguru, A.K., Jayakumar, K. and Ramakritinan, C.M. 2003. Coral bleaching 2002 in the Palk Bay, southeast coast of India. Current Science 85: 1787-1793.

In our Editorial of 18 Aug 2004, we describe the recent boost given by two important studies to the concept of symbiont shuffling, whereby successive episodes of the high-temperature-induced bleaching of corals lead to their being repopulated with species or subspecies of zooxanthellae that are ever more tolerant of high temperatures, which makes successive incarnations of coral reefs ever more resistant to new occurrences of warming-induced bleaching and more resilient in terms of their rate of recovery.

What was done
Kumaraguru et al. assessed the degree of damage inflicted upon a number of coral reefs within Palk Bay (southeast coast of India just north of the Gulf of Mannar) by a major warming event that produced monthly mean sea surface temperatures of 29.8 to 32.1C from April through June of 2002, after which they assessed the degree of recovery of the reefs.

What was learned
The authors report that "a minimum of at least 50% and a maximum of 60% bleaching were noticed among the six different sites monitored." However, as they continue, "the corals started to recover quickly in August 2002 and as much as 52% recovery could be noticed." By comparison, they note that "recovery of corals after the 1998 bleaching phenomenon in the Gulf of Mannar was very slow, taking as much as one year to achieve similar recovery," i.e., to achieve what was experienced in one month in 2002.

What it means
In words descriptive of the process of symbiont shuffling, the trio of Indian scientists say "the process of natural selection is in operation, with the growth of new coral colonies [following coral bleaching], and any disturbance in the system is only temporary." Consequently, as they conclude in the final sentence of their paper, "the corals will resurge under the sea."

Reviewed 29 September 2004