In early February, officials were worried vast sections of reefs in Kaneohe Bay might be overrun with a fast-moving and deadly coral disease.
Now it appears the malady has vanished and, in fact, the disease wasn’t even what officials thought it was.
Turns out a new kind of microscopic lesion, called "colony-wide protein losing cytopathology," or CPLC, was responsible for an unusual die-off of rice corals in Kaneohe Bay.
"The disease came and went. It’s not spreading," said Thierry Work, a U.S. Geological Survey wildlife disease specialist who discovered CPLC.
When signs of dying corals were first reported by the state’s Eyes of the Reef Network, crews were mobilized to conduct a field investigation. Researchers with the USGS, the Hawaii Institute of Marine Biology and state Division of Aquatic Resources conducted surveys of patch reefs in south, central and north Kaneohe Bay.
What they found at the central part of the bay was not good: On some reefs up to 90 percent of rice corals were afflicted with tissue loss, and the majority of those were thought likely to die. They collected coral samples in hopes of finding clues to the potential cellular processes that led to the mortality.
Initially researchers thought the disease was acute Montipora white syndrome, which was seen attacking the Montipora capitata rice coral of Kaneohe Bay during outbreaks in 2010 and 2012.
One researcher, noting the severity of the latest outbreak, described the apparent disease as an Ebola of corals and said all of the Montipora capitata, representing about 50 percent of the bay’s coral reefs, was at risk.
But the lab work pointed to something very different.
Work, a scientist with the USGS Wildlife Health Center Honolulu Field Station, found a unique lesion characterized by a leakage of proteins from coral cells. In humans this lesion is similar to pulmonary edema, in which proteins leak through cells and fill airways of the lung.
Work said the cause of colony-wide protein losing cytopathology is a mystery.
"Protein loss in cells with leakage to surrounding spaces as seen here suggests loss of cell membrane integrity," he wrote in a report about the discovery. "In other animals, protein loss in cells can lead to decreased defenses, making them susceptible to attack by secondary invaders that were seen in samples of corals manifesting mortality."
Noting that the corals of Kaneohe Bay look fairly healthy right now, Work said the newly discovered disease could be gone altogether, or it could still be lingering at low levels.
"We just don’t know," he said Tuesday. "This is a good example of how little we know about corals and how much more we need to know."
Alton Miyasaka, acting administrator for the Division of Aquatic Resources, said in a statement, "Since we don’t know the cause of this disease, we want to learn more, so we can determine what management actions might be taken to better respond to these events in the future."
Hawaii’s coral reefs have been plagued by outbreaks of bleaching and disease in recent years. Kauai’s coral reefs remain under attack from black-band disease, according to a new report that found the infection in nearly half of the corals surveyed around the island.
Last year scientists recorded the worst coral bleaching on record in Hawaii, and officials said our reefs could face warm-water conditions this summer that could produce even greater damage.
Dan Dennison, spokesman for the state Department of Land and Natural Resources, said aquatic officials are busy putting together summertime monitoring plans for both coral disease and bleaching.
Officials suspect that climate change and warming sea temperatures are contributing to stressing the reefs and making them more vulnerable to disease and bleaching.
Coral reefs are the foundation of the Hawaiian aquatic ecosystem, state officials said, and when the reefs are damaged, it suggests a deterioration of the whole ecosystem.
Hawaii ocean users are being urged to report any new coral disease outbreaks to the Eyes of the Reef Network at eorhawaii.org.
