How does rising atmospheric CO2 affect marine organisms?

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Coral Stress in the Florida Keys
Williams, D.E., Hallock, P., Talge, H.K., Harney, J.N. and McRae, G.  1997.  Responses of Amphistegina gibbosa populations in the Florida Keys (U.S.A.) to a multi-year stress event (1991-1996).  Journal of Foraminiferal Research 27: 264-269.

What was done
The authors present the results of statistical analyses related to the size and seasonal trends of episodes of symbiont loss in field populations of Amphistegina gibbosa and reproductive damage to the coral in the laboratory.

What was learned
The degree of bleaching exhibited a seasonal component, intensifying in the spring and peaking in the summer.  In addition, the severity of symbiont loss was greater for the larger coral samples.  Both of these trends remained consistent throughout the study.

The authors also noted that the proportion of corals that bleached in the summer declined over the period of study, while the proportion of young juveniles increased, suggesting a "recovery" of the corals and that their "symbionts may be adapting to the stress."

As for the cause of the stress, the authors state that although "the stress has not been identified, the trends and type of damage to the population are consistent with a mechanism related to solar irradiance."

What it means
This study demonstrates the potential link between coral bleaching and solar irradiance.  It also indicates the resilience and adaptability of certain corals exposed to stressful conditions.

Reviewed 1 May 1999