New study directly links human activity to red tide in Southwest Florida

Published: April 18, 2022 3:49 PM EDT
Updated: April 18, 2022 5:28 PM EDT

According to a new study, red tide and human activity can now be linked. The researchers linked blooms in Charlotte Harbor and surrounding coastal areas to nitrogen flowing from the Caloosahatchee River, Lake Okeechobee and areas upstream of the lake.

This report puts to rest the notion that people do not contribute to red tide. Researchers at the University of Florida say we absolutely do contribute. They say there is a cause and effect relationship between runoff into Lake Okeechobee and the Caloosahatchee and red tide.

Brackish water, dead fish, and a smelly beach are the tell-tale signs of red tide in Southwest Florida.

“They’re getting worse because of warmer temperatures but they’re also getting worse because of nitrogen runoff from human activity,” said Eric Milbrandt, director of the marine lab for the Sanibel Captiva Conservation Foundation (SCCF).

A new study from the University of Florida says nitrogen levels from fertilizer and septic tank runoff make red tide worse.

“It’s not saying that we start the red tides, but it’s that we can make them worse and that this happens consistently over time. There’s been, I think, an understanding that human activity can play a role. But because the system’s complex, and it’s hard to tease that apart, it hasn’t really been understood as a fact,” said Miles Medina, lead author on the red tide study for the Center for Coastal Solutions at UF.

Medina joined researchers from the SCCF and others to study blooms in Charlotte Harbor. Together they can now link red tide to discharges into the Caloosahatchee from Lake Okeechobee.

Calusa Waterkeeper John Cassani said he hopes lawmakers will use this study to take measures to stop nitrogen runoff.

“I think this information gives us a strong link and perhaps motivation to increase nutrient pollution restoration. So the restoration projects need to accelerate to reduce land-based nitrogen that causes these red tide blooms to be more intense,” said Cassani.

If you want to help reduce your impact on red tides in Southwest Florida, you can use plants in your garden that don’t need fertilizers. If you have a septic tank, investigate whether you can switch to a sewer system.