Disease hits Kāne’ohe Bay reefs

More than 100 colonies of red rice coral have been killed by MWS (the white cluster of coral above was once alive, the same color as the coral surrounding it). The disease appears most advanced in south Kāne’ohe Bay. (Credit: Hawaii Institute of Marine Biology)

MWS has killed 100 colonies of red rice coral

Honolulu Advertiser, April 5, 2010

By John Windrow

Hawai’i scientists are battling a new threat to coral reefs in Kāne’ohe Bay that could imperil the biological balance in the bay’s ecosystem.

The coral disease called Montipora white syndrome was discovered in the bay in late February, said lead researcher Greta Aeby of UH’s Hawai’i Institute of Marine Biology. She said that a similar outbreak devastated the coral reefs of the Florida Keys in the 1970s and ’80s.

Greta said a team composed of scientists and students from the Hawai’i Institute of Marine Biology, U.S. Geological Survey, National Wildlife Health Center and Bishop Museum are mounting a rapid response to study the disease, measure the damage it has done and come up with a way to contain it.

MWS has killed 100 colonies of red rice coral in the bay, which represents less than 1 percent of the bay’s coral colonies.

The disease appears to be most advanced in the southern part of the bay.

“It is not catastrophic at this point at all,” Greta said. “But this is the first documentation of a coral disease here in Hawai’i that causes a lot of mortality. We’ve never seen a disease like this to this extent.”

She said that the ecosystem in the bay is a delicate balance between the living tissue that lives in the reefs, the algae it feeds on, the small sea creatures and fish that live in the reefs and the larger fish that feed on them.

“The reefs are the foundation for the entire ecosystem,” she said.

Greta also stressed that coral reefs are inhabited by living tissue. “It is the living part of the coral,” she said. “It eats, feeds, grows and reproduces. Coral only grows at a rate of about 10 centimeters a year, so if you see a yard of coral that has died, that represents 10 to 15 years of growth.”

When the tissue dies, she said, the bare white coral that remains is the skeleton, the bare bones, of what was once a living, breathing organism.

She also said two external factors that imperil the reefs and can create conditions where a coral disease might flourish are sediment runoff from land around the bay and overfishing.

Greta said the response team’s plan is to measure the progress of MWS to see how widely dispersed it is and to collect samples of affected coral that will be “studied by microbiologists to try to determine what is causing this.”

The researchers’ goal, she said, is to devise a way to contain the disease.

To that end, the research group is enlisting the aid of a statewide group called Eyes of the Reef Reporting Network to be on the lookout for visible signs of the disease in the bay’s coral. The scientists train fishermen, tour guides, sportsmen and boaters and other community members who are often out on the water to help spot various threats to the marine ecosystem.

For more information, see www.himb.hawaii.edu/hawaiicoraldisease.

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