Everglades Dolphins Have World's Worst Mercury Contamination

First, the good news: Bottlenose dolphins still live along the South Florida coast and within the Everglades despite humanity's century-long quest to murder every creature native to the River of Grass.

Now, the bad: Those dolphins are dying, and Florida International University scientists now say the aquatic mammals that live in the Glades have soaked up more mercury than dolphins in any other habitat on Earth.

“This is a critical question for understanding the effects of pollutants on aquatic ecosystems, but also on humans, since we are also part of these ecosystems,” marine scientist Jeremy Kiszka, one of the study's authors, says in a news release.

Prior to northern settlers' arrival to South Florida (Native Americans had inhabited the land for centuries), the thin sheet of water that spread across the Everglades was unusually clean. But between farms pumping phosphorous into the ecosystem and decades of misguided attempts to drain and block the water flow, the ecosystem is now on life support.

Florida's most unique landscape has also been flooded with mercury. The National Park Service warns that fish in some areas of the Glades are so full of the substance that eating bass from areas near North Park Road in Homestead is seriously bad for your health.

One 1998 study said that most of the mercury in the Glades comes from quite far away, because the mangroves in the Everglades ecosystem are fantastic at "scrubbing" mercury from the air after it's been released into the atmosphere from as far away as Europe.

In 2012, Friends of the Everglades warned that the South Florida Water Management District is illegally dumping an average of 55,000 metric tons of agricultural waste per year into the Glades. That waste contains sulfur, which mixes with the mercury that's been dumped into the area to create methyl mercury, a neurotoxic substance dangerous to both fish and human beings. Pregnant women, especially, should not eat any fish caught in what was once the most pristine river in America.

But the problem isn't getting better, according to FIU's study, published Monday in the journal Environmental Pollution. The mercury might soon decimate the unique creatures that still make their homes in the area.

"During the past several decades, a variety of marine mammal species from all across the world have experienced unusual die-offs, including bottlenose dolphins along the East Coast of the United States," the university's researchers write in the report. The scientists blame much of that die-off on mercury, which can disrupt dolphins' immune and reproductive systems.

Dolphins still live in and around the Florida Keys, Everglades National Park, and Florida Bay — tourism officials love to push the fact that you might spot a school of dolphins on a Florida wildlife tour or boat trip during a stay here. But FIU's researchers say they don't know how long the cetacean creatures have been living with elevated mercury levels.

"Additional organic pollutants were examined as part of the study, including pesticides and other compounds," the researchers write. "Some were found in the various populations of bottlenose dolphins throughout the southern tip of Florida, but mercury was found in much more alarming concentrations in the waters of the Everglades."

The study's authors warned that they don't yet know the exact damage the mercury has done to the dolphins, nor do they know how much the poisonous metal affects other animals such as alligators, sharks, and other fish. But the signs aren't good.

It's been known for decades that agricultural runoff from Big Sugar farms — sulfur especially — is harming Florida's wildlife. But what's scary here is how little the state can do about mercury levels unless scientists find ways to stop mercury-filled clouds from crossing the ocean and raining all over Florida. Getting rid of the mangroves certainly isn't an option.


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