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Study: Active ingredient in world's most-used pesticides found in more than half of Florida manatees

According to the study, high concentrations of the ingredient were discovered in the Caloosahatchee and St. Lucie rivers before and during the sugarcane harvest.
Credit: AP
FILE - In this Dec. 11, 2017 file photo, manatees swim with their calves at Blue Spring State Park in Orange City, Fla. A combination of cold weather, a decline in seagrass due to development and contaminated waterways have put Florida on pace for its highest number of manatee deaths in a decade. Florida Fish and Wildlife Conservation Commission records show the 432 manatee deaths in 2021 is nearly three times the five-year average of 146 deaths between Jan. 1 and March 5. (Red Huber/Orlando Sentinel via AP, File)

ST. PETERSBURG, Fla. — An active ingredient in some of the world's most-used pesticides was found in more than half of a sample of Florida manatees, a recent study found.

Glyphosate, which is commonly used in pesticides like Roundup, was found in the plasma of 55.8 percent of manatees that were analyzed (a total of 105 animals) by a group of researchers. The concentration of the herbicide also "significantly increased" in Florida manatees over the past decade, the study adds.

According to the study's authors, high concentrations of glyphosate were discovered in the Caloosahatchee and St. Lucie rivers before and during the sugarcane harvest around the same time manatees rely on these warm bodies of water for refuge. 

Farmers tend to use glyphosate to ripen sugarcanes prior to harvesting them, but researchers say it's also used to control aquatic weeds in Lake Okeechobee. In fact, much of the discharge from the lake contained high concentrations of the herbicide, which is then funneled through both the Caloosahatchee and St. Lucie rivers.

The study concludes that chronic exposure to these pesticides could have serious consequences for the manatees' immune and renal systems, which they say are worsened by exposure to red tide or cold stress. These recent findings reveal more of the hurdles the state's manatees have been facing in recent years.

Florida is currently on pace to witness the deadliest years for manatees. 

The Florida Fish and Wildlife Commission's Manatee mortality report shows 432 manatee deaths in 2021, nearly three times the five-year average over the same period of time. The largest number of deaths is in Brevard County, with 179. Officials say many of those deaths occurred along the Indian River, which is a common warm water gathering place.

The sudden surge in deaths has caused a Florida congresswoman to ask for a federal investigation into the recent spike.

FWC has not commented on what is causing the rise of deaths, but the agency said it is investigating.

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