Human Sewage Linked to Mass Elkhorn Coral Extinction Threats

Researchers from the Rollins College in Florida and the University of Georgia have established for the first time that elkhorn corals, a species found in the Caribbean, have been infected and killed by a bacterium from human sewage.

The same bacterium, Serratia marcescens, causes respiratory problems in human beings. When the elkhorn corals are exposed to it, their soft tissues degrade, leaving behind only the organism's white skeleton.

"When we identified Serratia marcescens as the cause of white pox, we could only speculate that human waste was the source of the pathogen because the bacterium is also found in the waste of other animals," said Kathryn Sutherland, associate professor of biology at Rollins College.

The research team conducted a series of experiments to find out the exact cause. They collected and analyzed both human and other animals' samples from a wastewater treatment facility. The conclusion was that only the strain from human sewage matched the strain found in white pox diseased corals on the reef.

"The strain caused disease in elkhorn coral in five days, so we now have definitive evidence that humans are a source of the pathogen that causes this devastating disease of corals," Sutherland further stated.

Throughout the world, corals are facing severe treats of extinction from various causes, including rising temperatures and ocean acidification.

"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, professor of ecology at the University of Georgia.