University of Florida study links past Red Tide blooms to human pollutants


FORT MYERS, Fla – The two words no one wants to hear, red tide. Red tide is common during the fall months. This can lead to public health issues causing breathing and breathing problems. It is also a major environmental concern, resulting in large fish kills. Now we learn that these toxic algal blooms are made worse by the actions of humans, according to a new study from the University of Florida and the Sanibel Captiva Conservation Foundation.

The new evidence shows that humans are directly influencing the severity of red tide blooms 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 was the nitrogen inputs from the Caloosahatchee River that show a link, a causal link associated with the proliferation of red tides,” said Dr. Miles Medina, postdoctoral researcher at the Center. for Coastal Solutions from the University of Florida.

Dr. Medina is the principal investigator of the study. He says the nitrogen input that led to the bloom could be tracked hundreds of miles upstream.

“There’s kind of a signature, or fingerprint, of nitrogen inputs from the Caloosahatchee River,” Dr. Medina said. “We traced this nitrogen input upstream to Lake Okeechobee and the Kissimmee River.”

And while red tide blooms are a natural occurrence, human pollutants intensify the red tide into superblooms like Southwest Florida in 2018.

“Kind of kicking and holding flowers,” Dr. Medina said. “Evidence suggests that blooms last longer and are more severe due to nitrogen inputs.”

Although there is no specific point source, scientists have linked nitrogen and nutrient loading to agricultural fertilizers, underground septic tank leaks, and urban stormwater runoff; none of them are regulated by the Clean Water Act.

Sanibel Captiva Conservation Foundation scientist and co-author Dr. Eric Milbrant says there are things we can do to reduce these effects.

“Specifically, by supporting the conversion of septic tanks to sewers, following our ban on fertilizers during the wet period and essentially following the regulations that have been in place today and for several decades to limit the amount of nitrogen reaching the ocean. coastal,” said Dr. Milbrant.

Dr. Milbrant says that while this may not fix the problem right away, reducing the nitrogen will cause more isolated blooms or blooms that aren’t intense enough to be noticed.

“Due to the footprint of people and the number of people around our estuary and in our watershed to Lake Okeechobee, we need to continue to reduce nitrogen entering the coastal ocean,” said Dr. Milbrant.

The University of Florida is now looking to expand this study from the Caloosahatchee River to other estuaries like the Peace River and the Myakka River, expecting similar results.


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