Human waste is killing the coral reefs of Florida Keys

white pox disease (credit: James W. Porter, University of Georgia)

Clean seas, golden beaches and colourful coral reefs are all big attractions for tourists to the Florida Keys.

The popularity of the area though could be killing the very thing that the tourists come to see. New research has just been published showing the a bacteria found in human waste is the main cause of white pox disease in coral.

White pox disease threatens elkhorn coral.

The disease has impacted the Caribbean elkhorn coral so badly that in 2006 it was listed as an endangered species under the United States Endangered Species Act despite it once being one of the most common coral species in the region.

First research to show human pathogens harming marine corals.

The research found the white pox disease in coral is caused by Serratia marcescens and the strain of the bacterium found affecting the corals was the strain related to human sewage. This is the first time that research has shown that human pathogens can pass to marine invertebrates and cause harm.

This problem is not like hurricanes, which we can’t control. We can do something about this one.

Kathryn P. Sutherland, associate professor of biology at Rollins College, said ”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.”

The source of the bacterium being human waste was confirmed when the researchers compared the strain found at the coral reefs with the strains of S. marcescens found at Key West wastewater facility and strains found in waste from other wildlife species such as seagulls and deer. Genetic analysis showed that it was only the strain found at the Key West wastewater plant that was causing the white pox disease of the coral reefs.

“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 said.

Better wastewater treatment can reduce dangers of white pox disease.

Research colleague Professor of Ecology James W. Porter of the University of Georgia added, ”These bacteria do not come from the ocean, they come from us. We are killing the goose that lays the golden egg, and we’ve got the smoking gun to prove it.”

“Bacteria from humans kill corals—that’s the bad news,” said Porter. “But the good news is that we can solve this problem with advanced wastewater treatment facilities. This problem is not like hurricanes, which we can’t control. We can do something about this one.”

Waste water plants around the Florida Keys are currently undergoing major upgrades and when completed this source of the bacterium should come to an end and give the coral a chance to recover.

Ensuring that the seas around the coast of Florida Keys remain a colourful and diverse place is essential to the local economy. Water-born tourism such as snorkelling and diving brings in about $3 billion a year.