While humans can survive large temperature fluctuations, such species as corals are only comfortable within a 12-degree temperature range. And rising global temperatures appear to be threatening their survival, according to Drew Harvell, Cornell professor of ecology and evolutionary biology.
However, she noted in presenting a paper at the annual meeting of the American Association for the Advancement of Science in San Francisco, Feb. 18, Caribbean gorgonian sea fan corals show surprising warm-weather tenacity -- they not only are somewhat temperature resilient but can also boost their cellular and enzymatic defenses to fight lethal microorganisms as temperatures rise. These abilities may someday be harnessed to help protect other fragile coral reefs, Harvell said.
The head of the Coral Disease Working Group of the Global Environmental Facility Coral Reef Targeted Research Program, Harvell describes these latest findings in detail in the March issue of the journal Oceanography. The working group is an international collaboration with stations in the Caribbean, Philippines, Australia and East Africa that seeks to understand how rising ocean temperatures (which are monitored with high-resolution satellite detectors) are related to lethal coral reef epidemics.
The warm temperatures that have been occurring worldwide as a result of global warming appear to be facilitating fatal epidemics in coral reefs across the globe, according to Harvell and her co-researchers. For example, in 2005, the Caribbean experienced unusually warm weather and a spate of coral deaths caused directly by temperature stress and indirectly by opportunistic infections contracted during the warm period.
"Below the waves, the warm temperatures triggered a series of events lethal to coral reefs: massive loss of critical symbionts, compromised immunity and ability to fight pathogens, and increased susceptibility to lethal infectious microorganisms," reported Harvell.