Scientists say they have documented coral bleaching for the first time in the northern half of the Hawaiian archipelago. Coral bleaching is discovered
in northwest isles
By Diana Leone
dleone@starbulletin.comCoral bleaching is the loss of pigmented symbiotic algae cells from coral tissues, which makes coral lose its characteristic colors and look "bleached," said scientists with NOWRAMP 2002 (Northwestern Hawaiian Islands Reef Assessment and Monitoring Program [ PDF ] ).
It is one way corals respond to environmental stresses, such as unusually high water temperatures and exposure to strong solar ultraviolet radiation, and may be an indicator of global warming, scientists said.
NOWRAMP scientists say the discovery is important because coral bleaching is a serious problem in many reefs worldwide. However, coral bleaching was not reported on NOWRAMP expeditions to the Northwestern Hawaiian Islands in 2000 and 2001.
Chief scientists Rusty Brainard and Randall Kosaki, who remain at sea on research ships, said in a statement released yesterday that the coral bleaching is the most significant finding of their expedition since it embarked Sept. 8. The multigovernment-agency program is based out of Hawaii.
Large-scale bleaching was recorded at the northern end of the Northwestern Hawaiian Island chain at Pearl and Hermes, Midway and Kure atolls. So far, only minor bleaching has been reported at reefs at the southern end of the northwest islands, closest to the main Hawaiian Islands, but the trip continues until Monday.
Expedition biologists report that despite the varying levels of bleaching found, the coral reef ecosystems of the Northwestern Hawaiian Islands are healthy and among the most pristine in the world.
"It's important not to overreact to the evidence of coral bleaching we've observed during this trip," said Greta Aeby, a coral biologist with the state Department of Land & Natural Resources. "In severe cases, coral bleaching can cause mortality, but most mildly bleached colonies will recover in a few weeks."
Aeby added: "The higher-than-normal levels of bleaching we've found in these northwestern islands are unusual in the Hawaiian Islands but are not necessarily indicative of long-term environmental problems in these reefs."
