Red tide is back on some of Florida's southwest beaches, bringing dead marine life and an acrid scent to shores, and Tropical Storm Nestor might be to blame.
The storm, which made landfall on Florida's northern gulf coast on Saturday, was fast-moving and spun off at least three tornadoes in the state.
Florida Gulf Coast University's Dr. Greg Tolley told NBC affiliate BBH that wind speed, wind direction and rainfall can all affect whether a storm triggers red tide.
He said that while this wave of red tide appeared to be normal given the time of year, he'd have to continue monitoring the situation to tell whether Nestor had caused a change.
Beach-goers on the coasts of Collier County and Lee County, including Sanibel Island, were surprised to find dead fish lining the shores and a toxic smell in the air that can cause coughing.
Between the two counties, almost 40 turtles were also found washed up on shore. Only five were alive.
Red tide consists of algal blooms, which can be caused by an up-welling of nutrients from the sea floor following a massive storm.
Earlier this month, NBC 6 reported that red tide had come back to Florida's southwest coast after fading away earlier in the year following a 15-month bloom.
The 15-month bloom caused respiratory irritation in people and killed sea turtles, manatees, dolphins and fish.