Disease strikes rare coral at 7MB dive site

Diseased coral (Photo courtesy of the DoE)

(CNS): The Department of Environment has begun investigating a case of disease which is infecting a rare type of coral that is recognised as a threatened species. What is believed to be an outbreak of black band disease, possibly white plague and even red plague, though the exact cause has not yet been confirmed, has struck a collection of pillar corals at a dive site off the coast of Seven Mile Beach. Whatever turns out to be the culprit, what is certain is that the entire colony of dendrogyra cylindrus at the ‘Killer Pillar’ dive site shows severe signs of disease, which could kill off the impressive corals, officials have said.

The DoE is working on developing a response plan for these particular corals in an effort to save what is an uncommon type of coral in local waters and one of many coral species under threat around the world.

DoE Deputy Director Tim Austin said that formally identifying the diseases that are present at the site will require lab work in the United States. But in the meantime, most experts the department has consulted so far agree that it looks very much like black band disease, which affects many different corals on the reef.

“There is also a possibility that there is some white plague disease present too, and that also affects several kinds of corals on the reef and has been most recently responsible for a lot of coral mortality on our reefs. There isn’t a lot known about coral diseases other than that the impact is serious,” he said.

The delicate coral reef ecosystems around Cayman are under increasing pressure but protections are not keeping pace with the threats, as government’s current policy appears to be to back off from the necessary conservation required for our valuable marine resources.

But even with the much-needed enhanced domestic protections to control coastal development, overfishing and pollution, the waters around us remain extremely vulnerable to climate change. And coral disease is just one more pressure on the reefs that appears to be fuelled by a combination of warming waters and pollution in the ocean.

While no one is sure what causes it or where it comes from, terrestrial pollution, including sewage, has been suggested as a primary cause in the Florida Keys, Austin told CNS.

According to the National Oceanic and Atmospheric Administration (NOAA), coral diseases generally occur in response to stresses, including increased sea surface temperatures, ultraviolet radiation and pollutants, with one type of stress exacerbating others. The US scientific agency says that the frequency has increased significantly over the last 10 years.

“Many scientists believe the increase is related to deteriorating water quality associated with human-made pollutants and increased sea surface temperatures,” NOAA experts say.

Battling the disease is not easy, and Austin has said that the department is still trying to figure out what the options are, which will involve sourcing “some insurance pieces” of some living tissue that could be relocated in case the entire colony is lost.

The department also needs more information about other areas that may be impacted and they are reaching out to recreational scuba divers and local dive operators to help fill in some of the gaps while the DoE team develops a response plan.

Divers are asked to record the locations and number of colonies where they have seen pillar corals and to report on their overall health and the numbers showing disease, and to report any previous coral bleaching at the sites where there is evidence of disease, especially last year.

The DoE is also asking people to look out for three-spotted damselfish around the corals, as the ‘algae gardens’ of these damselfish can damage coral and may contribute to the spread of coral disease.

Divers are asked to send their findings to CoralWatch@gov.ky.

Pictures and video can be attached to the email or divers can join the Cayman Islands Coral Watch Facebook page and post images and videos there.