HONOLULU — Black band coral disease is affecting nearly half of the reef sites researchers have surveyed in waters off Kauai, the state Department of Land and Natural Resources said.

Researchers with the Hawaii Institute of Marine Biology are working with state and federal agencies to learn more about what's driving the disease. It was first identified in 2004 and rose to outbreak levels in 2012.

This is the first outbreak in Hawaii and the closest other outbreak is in Palau, said Christina Runyon, one of the lead researchers. It's a disease found globally around the tropics.

Runyon has spent the last two years surveying reefs around Kauai. Black band disease was found at 23 of the 47 sites, she said, with hotspots on the north and east sides of the constantly eroding island. The disease hasn't been reported on any other island.

"We also have been able to see that there's a trend between higher temperatures and this disease prevalence, where you see more of this disease when temperatures are warm," she said. "This is concerning to us because of the predictions for sea surface temperatures to be higher this year than last year."

During cooler months, the diseased colonies subside.

Researchers are having some success reducing coral tissue death using a novel, experimental treatment that involves using a putty-like substance over the coral lesions to smother the disease. "This is a Band-Aid," Runyon said. "What we need to do is clean up our watersheds."

Stress from warmer-than-average ocean temperatures prompted many of Hawaii's corals to expel algae last year — a phenomenon called bleaching.

Coral health is important to Hawaii economically, ecologically and culturally, Runyon said.