Dolphins with Elevated Mercury Levels in Florida and Georgia


In a study with potential implications for the oceans and human health, scientists reported elevated mercury levels in dolphins in the US Southeast, with the greatest levels found in dolphins in Florida’s St. Joseph and Choctawhatchee Bays.

Dolphins are considered a “sentinel species” for oceans and human health because, like us, they are high up in the food chain, live long lives, and share certain physiological traits with humans. Some staples of their diet, such as spot, croaker, weakfish, and other small fish, are most vulnerable to mercury pollution and are also eaten by people.

The study, which appeared in the journal Toxics, drew no conclusions about Florida and Georgia residents’ mercury levels or the potential health risks to humans. It did, however, cite previous research by a different group of researchers that found a correlation between high mercury levels in dolphins in Florida’s Indian River Lagoon and humans living in the area.

“As a sentinel species, the bottlenose dolphin data presented here can direct future studies to evaluate mercury exposure to human residents” in the Southeast and other potentially affected areas in the United States, the authors of the study in Toxics wrote.

According to the US Environmental Protection Agency (EPA), fish is part of a healthy diet, and “for most people, the risk from eating fish and shellfish is not a health concern.” But the agency also says that “some groups of people, such as pregnant people, children, the elderly or those with weakened immune systems, are at a greater health risk of adverse health effects. Additionally, some individuals are at a higher risk for adverse health effects simply because they eat a lot of fish.”

In marine mammals such as dolphins, mercury toxicity can lead to reproductive failure, behavioral changes, and even death, according to a statement last year from the Minamata Convention on Mercury, a 2017 global agreement informed by the scientific consensus on mercury.