The National Park Service hosted its 22nd lecture in its ongoing monthly series Thursday to allow for a scientist with past ties to Buck Island Reef’s coral research an opportunity to discuss coral disease and how it’s presently one of the greatest potential threats reefs face worldwide.
Erinn Muller, a staff scientist and researcher at the Mote Marine Laboratory in Sarasota, Fla., at one time in her decade-long career served as an intern at Buck Island. Since those days she’s studied coral diseases all over the world. She said her entry into the specific field of studying coral diseases and understanding where, when and why outbreaks occur wasn’t intended.
“It became evident as I continued to work in the coral reef environment how important it is to understand what these diseases are doing so we can prevent them from occurring into the future,” Muller said.
Muller opened her discussion with facts about coral’s biological importance in the oceans, as it pertained to coral living on the reef and the fish and other organisms that live there as well.
Healthy coral, she said, was all the blues, greens, oranges and browns that we naturally associated with reefs. White patches and discolorations were the signs of unhealthy coral.
Then she made reference to the importance reefs serve economically, specifically referencing the state of Florida and where she currently resides.
Muller said the coral reefs provide about $6 billion to the Florida state economy and provide more than 70,000 jobs. “They’re an incredible resource to our state economically as well as biologically,” she said. “So imagine this is an incredible resource that you need to preserve not only for the biology and beauty of the ocean but also for your economic stability throughout the Virgin Islands.”
Muller went on to explain that corals were animals, not plants, susceptible to diseases just like humans, but also possessed a much less powerful immune system.
Muller said the symbiotic relationship corals have with other organisms, like algae, was also what made them so vitally important biologically.
“If corals didn’t have these algae that lived in their tissue, their tissue would be translucent and all you would see is the skeleton and they’d look white all the time,” she said. “This algae provides all the different blues, greens and browns that you see on the reef today and it’s essential for the corals to survive.”
Then the news became harrowing and as Muller showed pictures comparing Carysfort Reef in Florida in 1975 and then nearly 30 years later, and she said the situation here in the Virgin Islands wasn’t much different. Reefs that were once teeming with life were now nearly wiped out.
“Throughout the globe and particularly in the Caribbean corals are dying at an unprecedented rate,” she said.
Muller said particularly this was true of shallow water corals, like Elkhorn and Staghorn, and that the effects had only occurred in the last 20 to 30 years. Many are now listed under the Endangered Species Act as ‘threatened’ and Muller said she expected that listing to worsen in coming months.
Some of the more common coral diseases in the region, Muller depicted, were White Band, Black Band, Dark Spot, White Plague and Yellow Band diseases.
“We don’t know much about the bacteria or the viruses or fungi and pathogens that are driving these diseases,” she said. “What we know is they’re causing corals to die and it’s happening very quickly.”
One of the limitations to fully understanding what pathogens drive the diseases, Muller said, was that, at present, only 1 percent of marine bacteria can be cultured in a laboratory.
What her research indicates, she said, is corals are stressed in a number of different ways these days. One of the biggest environmental stressors in some of the recent bleaching events has been increasing water temperature.
“That seems to be the most common cause we see,” she said. “And when corals get stressed, corals get sick.”
She said the Virgin Islands as well as Puerto Rico were in the “epicenter” of the 2005 mass bleaching event.
Describing that event, she said, “It looked like it snowed underwater.”
Describing other work at Buck Island in 2009, Muller said research there indicated Caribbean Yellow Band disease “everywhere” on a certain species of coral with particular hot spots along its north and east sides.
“We had a hard time going down to a site and not seeing this disease,” she said.
Muller said while 2014 data shows Yellow Band as being less common than it did in 2009, many species still appear to be sick. Another disease, though not as lethal, is Dark Spot Syndrome, and Muller said it was affecting some different species now as well.
Despite the news, she remained optimistic about reef’s futures, adding that there are many beautiful reefs still left in the world, many right here on St. Croix.
“What we’re hoping is that the (corals) that are the ones left are resistant to disease and are the ones that will propagate and reform the reefs over time and hopefully continue the reefs that we have for the future,” she said.
Muller added that while the disease outbreaks have hit the Caribbean hard, some have been the effects of things happening on a global scale, like climate change, which results in increased water temperatures and ocean acidification.
“Diseases are happening on a global scale and we’re having a hard time managing them,” she said. “But one thing we know is that local impacts do matter and that they can be manageable.” For St. Croix, for example, better management of sewage outflow near Frederiksted needs to be implemented.
Citing a paper by a longtime St. Croix resident who also studies coral disease, the results were clear, she said, when Frederiksted was compared with what was happening upstream near Butler Bay.
“Within Frederiksted, every single coral disease that he monitored, which was about 10 of them, was more common in sewage impacted areas than in areas that weren’t impacted,” she said. “Just being able to clean up the water is something that can be a very real, manageable decision and allows for corals to withstand these global stressors.”
She continued, “It’s something our research has shown time and time again, that reducing local impacts allows the corals to be more resilient to the global impacts.”