Coastal 'killing zone' poses risk to humans

Contaminants found in wildlife may also threaten area residents

Published On: Jul 29 2013 11:04:42 PM EDT   Updated On: Jul 30 2013 03:09:09 PM EDT
ORLANDO, Fla. -

Experts say whatever is killing the animals in Florida's Indian River Lagoon could pose a threat to humans, as well.

“A great majority of these diseases are zoonotic, which means they're transferred from animal to man and the incidents are rising over the year,” says Dr. Greg Bossart, the chief veterinary officer at the Georgia Aquarium. 

The Aquarium runs the Conservation Field Station at Marineland.  Bossart is one of many researchers trying to figure out what has caused a killing zone in the once pristine Indian River Lagoon. 

In one year, alone, 300 pelicans, 100 manatees, and at least 51 dolphins have turned up dead.

Bossart says contaminants are one part of the problem. 

“We’ve found levels of contaminants that are very worrisome,” he says.

The levels of Mercury, for example, found in Indian River Lagoon dolphins is about 20 times higher than what humans are supposed to consume, which could pose a danger if the lagoon’s ecosystem is a source for human food.

“We’ve extended our study into fishermen who fish in the Indian River and found their levels of Mercury are very high, too.”

Bossart says dolphins are a sentinel species, animals whose health issues often indicate what’s in store for the whole ecosystem, including humans.

“It's in our own best interests to understand, because it will come around to bite us,” he says.

Bossart’s colleagues at the Conservation Field Station, Matthew Denny and George Biedenbach, gave Local 6 exclusive access to their photo identification program, a study of dolphins in the Matanzas River and beyond.  The study catalogs the unique markings of dolphins’ dorsal fins in order to assess the population of resident and transient dolphins in the region.  They say inventory is critical to understanding the health of the dolphins because it gives researchers like Bossart a definitive population to study.

“This area provides context,” says Matthew Denny, the Conservation Field Station’s field director. “By revisiting over and over again, we know these animals are year-long residents, so if they’re sick, whatever disease or ailments they’re contending with are here in this area, whereas transients, who knows where they’re bringing diseases from.”

The diseases, Denny says, range from RNA-viruses, to cancers, HPV, and other distinctly exotic infections.

“Some of these diseases we're finding in the dolphin population in the Indian River Lagoon we’re only finding in dolphins and humans, and in humans only in third world countries,” Denny explains. “We have people who are in the Indian River Lagoon who are fishing, swimming, using that ecosystem, that's a real concern for human health.”

So, researchers from multiple marine life institutes are focusing their attention here, but none has come up with one definitive reason why the once pristine ecosystem has become a killing zone.

"This is a very complex issue,” Bossart says. “I don’t think it's going to be a cause and effect problem although the biotoxins issue might be at the top of my list.”

Biotoxins, which are particularly harmful to eco-systems, are produced naturally by plankton in the water, but that natural process can be influenced by man-made factors.

“A lot of scientists, including myself, believe it's because we've altered the environment, altered the ecosystems; we've altered the climate and we’re actually encouraging the selection of new pathogens,” Bossart says.  “We've treated our oceans as toilets for centuries and now we're starting to see the effects of that.”

Just last week a federal government panel declared the number of dolphin deaths in the Indian River Lagoon as “unusual.” The government’s declaration frees up federal funds for more research.