Human Waste Dumped into Oceans Harms Coral, New Study Reveals

florida coral decline photo

Dead coral, Elbow Reef, Key Largo, Florida. Credit:

Elkhorn coral is endangered. And it's being threatened by us, as in humans, and what we flush down the toilet.

A recent study published in the journal PLoS One says that human sewage is largely responsible for a disease which is killing off elkhorn coral in Florida. It's called white pox disease, and at least one scientist argues that the problem goes far beyond the Sunshine State, and is likely contributing to coral decline worldwide. Well, no crap. Or maybe too much crap. The Nature Conservancy has more on the subject.

Apparently, coral reef specialists have long suspected this was the case. The study examined elkhorn coral in Caribbean Sea off of Florida. Researchers isolated a people poop pathogen --- Serratia marcescens --- that causes white pox on the elkhorn, AKA Acropora palmata. This species of coral has declined by almost 90 percent in the last 10 years in Florida. White pox leaves white, circular lesions on the surface of infected colonies, and can take out a colony in a matter of days, according to NOAA.

An abstract for the PLoS One study says:

Our results provide the first example of a marine 'reverse zoonosis' involving the transmission of a human pathogen (S. marcescens) to a marine invertebrate (A. palmata). These findings underscore the interaction between public health practices and environmental health indices such as coral reef survival.

Stephanie Wear, director of coral reef conservation for the Nature Conservancy's Global Marine Team, says the issue of human waste ending up in oceans is "pervasive throughout small island nations globally."

She's lived in the Caribbean, and says it's not all paradise. There is ongoing contamination from failing septic systems and overflows, much like we have here in the Great Lakes and other parts of the U.S. And just as human sewage can close a beach, it can do damage to coral. Even though this finding may not be a surprise, it's helped isolate at least one cause of coral decline.

What's the solution? Better treatment and socioeconomic conditions. Too many folks still use the oceans as their toilet (and the rivers and lakes, depending on where you live).

Still, humans, who are contributing to this species decline, also can contribute to healthy oceans, Wear says. See the Cool Green Science blog for more.

More on Oceans and Coral
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