Florida's Coastal Water Held More Plastic After Hurricanes Helene and Milton

Microplastic levels in coastal water around Tampa Bay and the Caloosahatchee rose after Hurricanes Helene and Milton in 2024, researchers at the University of Florida report. They measured the plastic by mass and compared it with water drawn from the same spots in calm conditions.

The authors say Florida sees hurricanes almost every year, and yet how much plastic its coastal waters carry during one is poorly understood. Their results appeared Oct. 20, 2026, in Scientific Reports. They present them as a look at how microplastics are released and spread during extreme weather, and as an argument for more sampling along Florida's coast.

Jessica Ritchie, Shenandoah Sedio and colleagues collected surface water at 12 locations across Tampa Bay, the Caloosahatchee River and the Caloosahatchee Estuary. Each sample was sorted into particles above and below 25 micrometers, finer than a human hair, then digested and analyzed by microscope and by pyrolysis gas chromatography/mass spectrometry, a method that identifies a plastic from the gases it gives off when heated.

Mass concentrations rose significantly after the storms. The largest increase at any one site was 62.22 micrograms per liter, in Tampa Bay, a single station's maximum rather than an average across the 12 sites or a figure for Florida.

The increase came from the smallest particles: it was pronounced in the finer of the two fractions rather than among larger fragments. Post-storm samples also carried more of the denser plastics, among them PVC and polymethyl methacrylate, the material sold as acrylic.

The authors place the result alongside earlier studies that had found elevated microplastic concentrations in severe weather, tropical cyclones among them.

The National Science Foundation and a University of Florida startup fund paid for the work. The journal published the paper open access, and the posted text is the accepted version and will be replaced by a final version of record.