Rollins College researcher gets to bottom of what's killing Keys coral reefs

Rollins College researcher gets to bottom of what's killing Keys coral reefs






Elk horn coral had been thriving in the Florida Keys and the Caribbean but it's been decimated in the last decade. One of the main killers is white pox disease, which is apparent on this elk horn coral for the white patches where the coral tissue has died, baring the white limestone skeleton underneath. Because of massive die offs, elk horn coral are now considered endangered species. (James W. Porter, University of Georgia, James W. Porter, University of Georgia / September 24, 2011)




By Ludmilla Lelis, Orlando Sentinel
10:29 p.m. EDT, September 24, 2011

Something new was killing the Florida Keys' elkhorn coral.
The coral, whose reefs provide vital habitat for fish, crabs, lobsters and other creatures, were dying from a disease called white pox, which destroys the coral's outer tissue. But what had caused the outbreak?
Fifteen years after seeing the disease for the first time, Kathryn Sutherland has found the answer. The professor in Rollins College's budding marine-biology program has conclusive evidence that the coral is being killed by human waste.
Sutherland, along with one of her students and University of Georgia researchers, recently published a paper showing that white pox is caused by a strain of bacteria traceable only to human sewage.

"From what I've researched, it's the first instance of a disease going from humans to invertebrates, and there's a lesson in that," she said. "If humans are causing this disease, we need to do something about it."
White pox was identified in the 1990s as yet another threat to a coral species once one of the most dominant on reefs in the Keys and the Caribbean. Named for its antlerlike branches, elkhorn has been so decimated by disease, hurricanes and other problems that in 2006 the federal government classified it as a threatened species. More than 90 percent of elkhorn coral has been lost, according to federal estimates.
Losing coral reefs would be devastating for the Florida Keys, which depends on ocean-related tourism for 58 percent of its economy, according to a federal study. Marine life attracts thousands of divers, snorkelers and anglers, who spend more than $300 million a year during their visits.
As a graduate student at the University of Georgia in the 1990s, Sutherland hoped to parlay a lifelong love of marine biology into a research career. She was studying elkhorn coral in the Keys when she recognized a new disease outbreak in 1996.
"I became very curious about this new phenomenon. What was it, and where did it come from?" she said.
The crucial clue came in 2003, when she isolated a bacterium, Serratia marcescens, that was found on sickly coral but not on healthy coral. It's a fairly common bacterium in humans, known to cause pneumonia, meningitis and other infections and found in untreated sewage. But it hadn't been seen in the marine environment before.
Because it's common knowledge that antiquated septic tanks in the Keys can leak sewage, Sutherland theorized that human sewage was harming the corals. But such an idea was novel — and untested.
During lab work at the Mote Tropical Research Laboratory in Summerland Key, Sutherland and her fellow researchers experimented with healthy corals in clean aquarium tanks and infected them with a strain of the bacterium from human sewage. A few Rollins students, including Hunter Noren and Sameera Shaban, assisted, getting hands-on research experience.
They also tested other pollutants on the coral, but the results were clear, she said: The fecal bacteria caused white pox to appear in as little as four days.
With the culprit confirmed, she and the Georgia researchers will continue to investigate the problem. With funding from a five-year, $2.2 million National Science Foundation grant, the team hopes to figure out what factors help the bacteria persist and flourish in seawater.
Scott Donahue, science coordinator at the Florida Keys National Marine Sanctuary, said the research shows the importance of protecting the Keys' environment.
"We've all known that water quality is critical to the overall health of the ecosystem," he said. "With a lot of diseases in coral, it's very hard to find the cause because of the nature of the environment. But that's the power of this paper."
Because the bacteria can be killed through wastewater treatment, there's hope for saving the corals, said Sutherland, who was hired along with another professor, Fiona Harper, six years ago to help the college expand into marine biology.
But building a new sewage system for the Keys has been enormously expensive.
Key West already has a wastewater-treatment system capable of killing the bacteria. But upgrading the rest of the islands is a $725 million project only 65 percent complete, Monroe County officials said.
"What this study suggests is that all the costs incurred for a centralized sewage system and to upgrade the wastewater treatment are taxpayer dollars well spent," said James W. Porter, a University of Georgia professor and co-author of the study. "If we take care of the environment, it will take care of us."
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I've personally witnessed Celebrity Cruise Lines dumping raw sewage (blackwater) into Key West harbor.
It was almost dusk, so they reckoned no one would notice. And yes, the reefs close to Key West are toast.
Good work on isolating the bacteria!