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University of Florida study linking past Red Tide blooms to human pollutants from the Caloosahatchee River

Posted at 6:10 PM, Aug 03, 2022
and last updated 2022-08-04 04:28:18-04

FORT MYERS, Fla. — The two words that no one wants to hear, red tide. Red tide is common in the Fall months. It can lead to public health concerns causing respiratory and breathing issues. It's also a major environmental concern, leading to large fish kills. Now, we’re learning these toxic algae blooms are being made worse by things humans are doing, according to a new study from the University of Florida and Sanibel Captiva Conservation Foundation.

The new evidence shows humans are directly influencing just how bad red tide blooms become in our local waterways. They looked at red tide events specifically related to the Caloosahatchee River between 2012 and 2021.

“In fact, what we found is nitrogen inputs from the Caloosahatchee River do show a link, causal link associated with the red tide blooms,” said Dr. Miles Medina, Postdoctoral Research Fellow, Center for Coastal Solutions at the University of Florida.

Dr. Medina, is the lead researcher on the study. He says that nitrogen input that led to blooms could be tracked hundreds of miles upstream.

“There is sort of a signature or fingerprint, from the nitrogen inputs coming out of the Caloosahatchee River,” said Dr. Medina. “We traced that nitrogen input upstream to Lake Okeechobee and to the Kissimmee River.”

And while red tide blooms are a natural occurrence, human pollutants are intensifying red tide into super blooms like Southwest Florida saw in 2018.

“Sort of kicking the blooms off and also sustaining them,” said Dr. Medina. “The evidence suggests that the blooms are lasting longer and are more severe due to the nitrogen inputs.”

While there is not a specific point source, scientists have linked the nitrogen and nutrient loading to agricultural fertilizers, underground septic tank leaks and urban stormwater runoff; none of which are not regulated by the Clean Water Act.

Dr. Eric Milbrant, a coauthor and scientist with the Sanibel Captiva Conservation Foundation says there are things that we can do to reduce these effects.

“Specifically, by support septic to sewer conversion, following our fertilizer ban during the wet period and by basically following regulations that are in effect today and have been for the several decades to curb the amount of nitrogen getting to the coastal ocean,” said Dr. Milbrant.

Dr. Milbrant says while this might not fix the problem right away, reducing nitrogen will lead to more isolated blooms or blooms not intense enough to be noticed.

“Because of the footprint of people and the amount of people around of our estuary and in our watershed up to Lake Okeechobee, we need to continue to reduce nitrogen that gets into the coastal ocean,” said Dr. Milbrant.

University of Florida is now also looking to expand this study of Caloosahatchee River to other estuaries like the Peace River and Myakka River, with the expectation of similar results.