Florida Dolphins Show Highest Mercury Levels Ever Recorded In The Species - Miami Herald
Bottlenose dolphins swimming off the Florida Everglades, beloved for zipping alongside lonely boaters in the remote bays and rivers chiseled out of the vast marshes, have the highest levels of mercury ever documented in the mammals, researchers have found. But why that is may not be so easy to unravel.
The findings surfaced in a study in the journal Environmental Pollution that looked at pesticides and toxins in South Florida dolphins. Dolphins are considered a sentinel species, providing valuable insight into ecosystems and public health. Last year, for example, in a study that looked at dolphins in the Indian River Lagoon, researchers discovered that elevated mercury levels in dolphins accurately reflected high amounts in the nearby human population. But in the Everglades, nothing is ever simple.
The high amounts of mercury likely come from the miles of mangrove that line the coast and form countless islands, said Florida International University marine ecologist and co-author Jeremy Kiszka. Mercury in the Everglades has long been linked to smoke stacks and fertilizer used in farming and led to declines in birds as well as repeated health warnings over eating fish. But aggressive cleanup efforts have helped reduce levels.
Still, mangroves are remarkably efficient at producing and trapping mercury, and filtering it into the water, so determining where the toxic mercury comes from, and how long its been there, remains poorly understood, researchers say.
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