Some corals surviving higher temperatures

Last Updated: Mon, Feb 04, 2013 05:30 hrs

London, Feb 4 (IANS) Some coral reefs in the Arabian or Persian Gulf are surviving harsher temperatures, even though many are gradually dying under the impact of global warming, say researchers.

Already, around 30 percent of the world's coral reefs are severely damaged; more than half of coral reefs worldwide may be lost in the near future because of global warming.

Coral reefs' ability to survive adverse conditions in the Gulf is now being investigated by researchers from the National Oceanography Centre, Southampton (NOCS) and New York University Abu Dhabi (NYUAD), the journal Marine Pollution Bulletin reports.

Coral reefs thrive at a temperature of around 28 degrees Celsius, and even slight warming can have devastating effects. But those in the Arabian or Persian Gulf withstand maximum temperature of 36 degrees Celsius, enough to kill corals elsewhere, according to an NOCS and NYUAD statement.

"We have established successful laboratory cultures of Gulf corals," said Jorg Wiedenmann, head of the Coral Reef Lab and senior lecturer at the University of Southampton Ocean and Earth Science, both of which are based at NOCS.

"This will greatly accelerate the progress of unravelling the mechanisms that underlie their surprising heat resistance."

Reefs are made up of many species of coral, each of which have a mutually beneficial, or "symbiotic," relationship with algae living in their tissue. Even a temperature rise of just one degree Celsius can harm the symbiotic algae, which in turn can increase mortality in corals.

"In Gulf corals, both the coral host and the associated algal partners need to withstand the high seawater temperatures," said Wiedenmann who led the study. But the scientists were surprised to discover that the algae in Gulf corals belong to a group not known for its thermal tolerance.

"Gulf corals are living at the limit of their tolerance," said co-author John Burt, professor from the NYUAD. "We have observed an increased frequency of coral bleaching events in this area, and we need to act now to protect and understand these ecosystems that hold the answers to many important climate change related questions."

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