Scientists have discovered that bottlenose dolphins in the Florida Coastal Everglades have higher concentrations of mercury in their bodies than any other population in the world.
This discovery was made when scientists from Florida International University (FIU), University of Liège in Belgium, the University of Gronigen in the Netherlands and the Tropical Dolphin Research Foundation in the United States examined dolphins from the lower Florida Keys, Everglades National Park and Florida Bay for mercury and organic pollutants in their skin and blubber. The mercury levels in the coastal dolphins were high; in fact, it was the highest levels of concentration ever recorded.
FIU marine scientist Jeremy Kiszka said, “Results obtained on bottlenose dolphins from the Everglades were surprising, but we now need to assess the effect of mercury on the health of dolphins and other species from the Everglades. 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.”
In the past decades, the populations of a variety of marine mammals worldwide have experienced unusual die-offs along the East coast of the United States. Toxic algae and toxic pollutants are believed to be the culprit.
Mercury is a substance that can disrupt the dolphins' immune system and reproduction. The mercury could have come from both natural and man-made sources. However, mangroves are believed to be the main source. When leaves fall into the swamp waters, the mercury from the mangroves interacts with bacteria and is turned into methylmercury, which is highly toxic.
Other organic pollutants like pesticides and other compounds were also covered in the study, and these were indeed also found in the bottlenose dolphin populations along the southern tip of Florida. However, mercury was found in highly alarming concentrations in the waters of the Everglades.
For the next stage of the research, the scientists intend to extend their study to other animals, including fishes, sharks and alligators.