Rising sea temperatures in the Caribbean have provided scientists with the opportunity to study the effects of warmer water on a particular species of algae. In a paper to be published in the Proceedings of the Royal Society B, researchers led by Penn State biologist Todd LaJeunesse describe their study of coral in the Caribbean during a particularly warm stretch in 2005. During the warming event, the normally rare algae known as symbiodinium trenchi flourished, even as other species disappeared from their symbiotic coral homes. With an increase in recorded frequency of up to 50%, Symbiodinium trenchi's exceptional temperature tolerance clearly gave it a competitive edge, as increased water temperatures of up to two degrees Celsius killed off more vulnerable types of algae.

The overall impact of a long term shift in the algal balance of power remains unknown, however -- ocean temperatures dropped back down after a few months, the usual algae populations returned, and symbiodinium trenchi returned to obscurity. Since it does not seem likely that this rare algae coevolved with Caribbean coral, the long term stability of their potential symbiosis remains a question mark.

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