Human sewage is source of deadly disease in coral

Researchers at the University of Georgia have discovered genetic evidence that points to human waste as the source of the pathogen that is killing coral.

Human excrement is killing coral reefs in the Florida Keys.

For nearly a decade, researchers suspected human waste was the source to blame, but have never been able to prove it until now. Scientists have discovered that a certain type of pathogen from human waste is infecting coral reefs.

To be sure, researchers at the University of Georgia collected human samples from a wastewater treatment facility in Key West and compared it strains found in other animals such as cats and seagulls.

In the lab, a strain of fecal bacterium from humans and animals, called Serratia marcescens, was isolated and put on coral fragments which had been taken from the ocean. Only the coral exposed to the human strain showed signs of white pox disease. It only took five days for signs of illness to show. More importantly, the tests proved what the scientists had long suspected: That bacteria from human waste as to blame for causing white pox disease in coral and now they had the genetic evidence to prove it.

In humans, the pathogen causes a slew of health problems, including respiratory, wound and urinary tract infections, and pneumonia. The same strain of bacteria causes white pox disease of Caribbean elkhorn coral, which is an infection that makes white blotches form on the coral's tissue, leaving the skeleton exposed. Given that the population of elkhorn coral in the Florida Keys has declined by 90 percent over the past 15 years, it's a endangered species.

Scientists know that pathogens spread from wildlife-to-humans like with bird flu and HIV, but this is the first time human microbes have been shown to be pathogenic to marine invertebrate. Even in remote places such as Dry Tortugas, human diseases are affecting wildlife. Scientists suspect the disease is transmitted from human waste to snails to coral.

"Bacteria from humans kill corals -- that's the bad news. But the good news is that we can solve this problem with advanced wastewater treatment facilities," said James Porter, a professor at the University of Georgia, in a statement. To fix the problem, wastewater treatment plants need to be upgraded to properly treat the bacteria before can infect nearby coral reefs.

"In many ways, this particular species are like the redwoods of a forest," Porter told PBS Newshour. "They're the large branching iconic species. An analogy would be as if 97 percent of redwoods died in Sequoia National Park."

via The University of Georgia

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