dying coral

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Common human bacteria linked to disease killing Caribbean coral strain

 

Tuesday, June 18, 2002

By Randolph E. Schmid, Associated Press

 

WASHINGTON — Bacteria found in the intestines of humans and other animals have

been identified as the cause of a disease killing elkhorn corals in the

Caribbean Sea.

First reported in 1996, the disease has spread widely, causing severe damage to

the branched corals.

 

On some reefs near Key West, mortality of elkhorn coral has reached 95 percent,

and the disease has been recorded in the U.S. Virgin Islands, Caribbean areas of

Mexico, the Bahamas, and Florida, said James W. Porter of the University of

Georgia.

 

Porter and his research team traced the white pox disease that causes the

problem to Serrate marcescens bacteria, which are widely found in the intestines

of humans and other animals. The findings are reported in Monday's issue of

Proceedings of the National Academy of Sciences.

 

" Elkhorn used to be the commonest coral in the Caribbean, but now it has been

proposed for inclusion on the endangered species list, " Porter said. " Elkhorn

coral is the giant redwood of the coral forest. "

 

Asked how the bacteria got to the coral, he said, " We don't know.... We are

investigating the possibility that the origin of the bacteria is human waste,

but we don't know. " That is a crucial question in the Florida Keys, where most

waste is treated in septic fields rather than undergoing extensive treatment to

kill the bacteria.

 

" The implications for people in the Florida Keys are high, " Porter said.

Discussions are under way into improving wastewater treatment, he said, but it

costs a lot and state and federal help are not assured. " Everyone down here is

in love with the water, " he said. " They want to do the right thing, but the cost

to maintain the highest water quality standards could be prohibitive for the

individual citizenry. "

 

The city of Key West, the largest in the Keys, last October opened a $67 million

upgrade of its wastewater collection system and a new advanced treatment plant,

city spokesman Andy Newman said. Major hotels also have their own

sewage-treatment facilities, he said.

 

Cheva Heck of the National Oceanic and Atmospheric Administration's Keys

National Marine Sanctuary agreed that while the bacteria have an association

with humans, " The research itself doesn't tell us where it comes from. "

 

Dale W. Griffin of the U.S. Geological Survey's Center for Regional and Coastal

Studies in St. Petersburg, Fla., said he found it interesting that bacteria with

a fecal source have been identified as pathogens in the reef. " One of the

primary concerns in the Florida Keys is the waste disposal problem, " said

Griffin, who was not part of the research team. He noted the paper made no

conclusion about the source of the bacteria killing the corals.

 

Coral colonies affected by white pox have irregularly shaped white spots which

eventually grow and kill the coral by consuming the thin layer of living tissue

that covers a coral's limestone skeleton. The bacteria can grow by as much as a

one-half-square inch to three square inches daily.

 

Treating the infected coral also poses problems, as the bacteria have become

resistant to antibiotics, Porter said in a telephone interview. Meanwhile,

stress caused by the warming of the waters in the region is weakening the

corals, making them more vulnerable to infection, he said.

 

White pox disease has struck only elkhorn coral so far, something Porter found

surprising. Other corals have their own problems, such as bleaching when the

algae that populate and build the corals die off. That problem that has been

increasing, and many blame on global warming.

 

Coral reefs are under assault worldwide, according to the United Nations, which

blames global warming, fertilizer and sewage runoff, and even fishers' use of

dynamite in some areas.

 

Besides the University of Georgia, where Porter is a professor of ecology,

researchers on the project came from the Scripps Institution of Oceanography,

the company MicroGenomics, Clemson University, Mote Marine Laboratory, Tetra

Tech Inc., the Environmental Protection Agency, and the University of South

Carolina.

 

 

Copyright 2002, Associated Press