Black line is cyanobacteria separating areas of dead ( right) and living coral.
Image: Thierry M. Work

Scientists are trying to figure out the cause and extent of a coral-killing disease that has been documented on some North Shore Kauai reefs.

Dr. Thierry Work, a wildlife disease specialist with the U.S. Geological Survey, and Dr. Greta Aeby, a coral expert with the Hawaii Institute of Marine Biology, have spent the past several months studying reefs at Anini and Makua that appear to be suffering from an infectious outbreak of cyanobacteria that Work characterized as an “epidemic.”

Work said the first time he documented cynaobacteria in Hawaii was in Hanalei Bay in 2009, “but the widespread distribution and number of corals affected is something I’ve only seen on North Kauai.”

The Makua and Anini reefs are heavily degraded by turf algae as well as sediment settling on the coral, he said. Though these conditions appear to be driving the coral disease, it has also been seen in North Kauai areas without sedimentation.

“This disease is a manifestation of something awry in the ecosystem,” Work said, noting it “absolutely” could be linked to sewage, as well as sediment. “I think I can safely make the conjecture that what we do on land in the Hawaiian Islands has a direct impact on the reefs.”

As scientists try to understand more about the disease, “hopefully management agencies can work on their end to mitigate land-based activities that could be contributing,” Work said. “I’m hoping this serves as a catalyst.”

Terry Lilley, a Kauai recreational diver, first alerted scientists to the outbreak.

“The thing we’re concerned about here is the Western Caribbean and Atlantic lost 60 to 70 percent of their corals due to disease, but have no idea why,” Work said. “We don’t want that to happen in the Hawaiian Islands. We really depend on members of the public to keep an eye out.”