Algae may shield coral from global warming

The team, led by Pennsylvania State University Assistant Professor Todd LaJeunesse, evaluated corals -- and the photosynthetic algae that live inside their cells -- before, during and after a period in 2005 when global warming caused Caribbean Ocean sea-surface temperatures to rise.

"Symbiodinium trenchi is normally a rare species of micro-alga in the Caribbean," LaJeunesse said. "Because the species is apparently tolerant of high or fluctuating temperatures, it was able to take advantage of the warming event and become more prolific. In this way, Symbiodinium trenchi appears to have saved certain colonies of coral from the damaging effects of unusually warm water.

"As ocean temperatures continue to rise as a result of global warming, we can expect this species to become more common and persistent," he added. "However, since it is not normally associated with corals in the Caribbean, we don't know if its increased presence will benefit or harm corals in the long term. If
Symbiodinium trenchi takes from the corals more than it gives back, then over time we will see the health of the corals diminish."

The team's findings appear in the online version of the Proceedings of the Royal Society B.

Copyright 2009 by United Press International.