Hurricanes can help coral reefs
July 17, 2007
A close call with a hurricane can be beneficial to a stressed coral reef, reports a study published in Proceedings of the National Academy of Sciences (PNAS).
The new research shows that hurricanes, which can form when surface temperatures reach about 28 degrees C (about 82 degrees F), cool sea temperatures by stirring up colder waters from ocean depths. The action brings relief to coral "bleached" by warm waters. Bleaching refers to the expulsion of the symbiotic algae that enable corals to feed. Corals can recover from short-term bleaching, but prolonged bleaching -- over a week -- can cause irreversible damage and subsequent death.
Time-series of bleached coral (Colpophyllia natans) at Coral Gardens, Florida Reef Tract. (A) Prebleaching (August 11, 2005). (B) Bleached (September 6, 2005). (C) Nearly recovered (November 9, 2005). (D) Recovered with normal pigmentation (March 2, 2006). (Photo courtesy of the Proceeding of the National Academy of Sciences)
"The area affected by hurricane cooling is much larger than the narrow bands where damage actually occurs to reefs. Clearly, hurricane cooling isn't expected to completely negate the effects of climate change on coral reefs, but a well-timed hurricane or hurricanes has the potential to mitigate the negative ecological consequences associated with severe temperature disturbances," added co-author Marilyn Brandt, a graduate assistant in the Rosenstiel School marine biology and fisheries division.
The researchers say their work is the only known scenario where hurricane effects have been shown to benefit a stressed marine community.
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