Scientists continue to look for clues to what is causing an outbreak of skin disease in Hawaiian puffer fish on Kauai’s North Shore, but have had some success using a marine epoxy to slow the large-scale kill-off of diseased coral in the same area.
"Something’s going on on that North Shore," said Greta Aeby, assistant researcher at the University of Hawaii Institute of Marine Biology.
A study of Hawaiian puffer fish plagued with a skin disease continues, with UH scientists and the U.S. Geological Survey surveying four areas during their latest visit to Kauai from May 29 to June 5.
They are trying to determine the cause and prevalence of the disease, which affects the Hawaii white-spotted toby fish, Canthigaster jactator, commonly referred to as puffer fish.
Seventy fish were observed at four of the five sites — three in Anini, one off Charo’s in Hanalei, and Makua Lagoon.
At one site in Anini, five of 22 fish, or 23 percent, had the disease, according to Aeby. That site had the highest prevalence of puffer fish among the five.
One site in Anini had no signs of the fish.
Signs of the skin disease include discoloration, inflammation and ulceration, or rotting skin. The normal skin color is olive green or brown with small polka dots.
With the assistance of marine videographer Terry Lilley, experts from UH and the USGS first noticed lesions on puffer fish in October while documenting a coral disease outbreak.
In that outbreak a type of blue-green algae was documented on an unprecedented scale.
Aeby said they plan to return to Kauai in July to continue research.
So far, blue-green algae, or cyanobacteria, are affecting three coral species: red 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.
In October, researchers photographed sites of dying coral in Anini and applied marine epoxy, a claylike substance, to the bacteria on eight colonies of red rice coral to slow the growth of the disease. Eight other nearby colonies were left untreated as a control group.
Researchers from UH and USGS returned to the sites two months later and discovered about 4.4 percent of each red rice coral colony treated with epoxy was affected by the disease.
About 65.9 percent of each of the eight untreated red rice coral colonies were wiped out by the bacteria.
"(The epoxy) basically slowed the disease a lot, so that’s good," Aeby said.
"This is a fairly lethal disease," she added.
The application of clay to stop the spread of bacteria on coral was first used in the 1980s at the Florida Keys by reef specialist Harold Hudson. He used a single band of modeling clay in an attempt to slow the bacteria growth.
UH researchers modified the treatment by using marine epoxy, which they found to be more moldable. A second band of epoxy is also applied to diseased coral if the first band isn’t successful.
Aeby said they plan to apply marine epoxy to the other affected coral species when they return to Kauai in July.
