A new bacterial disease off Kauai’s North Shore is quickly killing coral, federal biologists say.

"The coral reefs are telling us something," said Thierry Work, a wildlife disease specialist with the U.S. Geological Survey’s National Wildlife Health Center in Honolulu. "We’re doing poor management of our coastal system."

Crescent-shaped lesions are advancing across the reefs and leaving behind a trail of exposed skeleton, the scientists say.

Researchers so far have observed the lesions on three coral species: rice coral or Montipora capitata; ringed rice coral or Montipora patula; and blue rice coral, Montipora flabellata. The last two species are proposed to be listed as threatened under the Endangered Species Act, according to Bernardo Vargas-Angel of the Coral Reef Ecosystem Division of the National Oceanic and Atmospheric Administration.

"I haven’t observed anything like this in Hawaii," Vargas-Angel said.

Vargas-Angel and three other researchers returned Tuesday to Oahu from Kauai, where they spent more than a week studying lesions and filamentous bacteria affecting coral colonies. The research team plans to analyze the data and expects to have results on the percentage of colonies affected by the end of the month.

NOAA researchers focused their study on two sites in Hanalei and one each in Wainiha and in Anini. The team has been collaborating with researchers from the University of Hawaii and the USGS to determine the cause of the quick-spreading disease after they heard about outbreaks at Anini and Makua in August and October.

Vargas-Angel said he had seen coral lesions on Kauai’s North Shore in 2010 but not to this extent.

"We don’t know exactly what’s causing it at this point," he said. "It’s disheartening to see coral dying, and dying so fast, especially when there’s so much to learn about the potential drivers."

Work, the USGS researcher, was on Kauai’s North Shore last month and focused his study on the same four sites.

"The lesions that we see in Kauai are very different than the ones we’ve seen (previously) in the Hawaiian Islands," he said. "They’re definitely unusual."

There are two types of filamentous bacteria infecting the coral: cyanobacteria and gliding bacteria.

"We would like to find what is driving this," Work said.

But determining the cause will take some time, he said. 

He called for improvements in environmental conditions on reefs to maximize the recovery and reproduction of coral colonies.