Another research study implicates nutrient pollution in exacerbating red tides

New research finds that human pollution influences the severity of red tides more directly than scientists previously understood. The connection sheds light on the need for better water-quality monitoring statewide — and ultimately, to reduce the nutrient pollution flowing into Florida’s waterways.

While red tides occur naturally, scientists have long debated the degree to which they are worsened by high levels of nutrients such as nitrogen from human sources agricultural and urban. Scientists had previously found correlation between so-called nutrient loads and red tide. But the new research offers some of the strongest evidence yet that humans directly influence the severity of the toxic blooms.

The study focuses on the Caloosahatchee River in Southwest Florida, which carries water and pollutants from Lake Okeechobee as it flows west to the Gulf of Mexico.

In the past, scientists looked for a direct relationship between nitrogen and red tide. But excess nitrogen doesn’t cause red tide — it exacerbates it, an effect that can take weeks. Looking for a short-term correlation did not implicate pollutants.