Saharan dust moves toward Florida; a reason to monitor water quality

Sunsets across Florida could become more spectacular soon, as clouds of dust from the Sahara Desert are sweeping in across the Atlantic Coast in the coming days.

Similar to the way humans need iron, Saharan dust provides iron to organisms in the water. In turn, it can fuel events such as red tide.

FGCU professor Mike Parsons told us that includes algae.

“So the dust brings the iron that they were lacking, and it helps them grow,” explained Parsons, who is the director of the Vester Field Station and teaches at FGCU’s The Water School.

A photo from 2020 shows trichodesmium, or sea sawdust, which is an algae in the Gulf. It takes hold of iron from the dust.

“The hypothesis is … when you have these trichodesmium blooms, they take that nitrogen gas, and they turn it into fertilizer,” Parsons said.

It’s fertilizer that red tide will gobble up, but there’s a catch.

“The conditions have to be very specific that will allow red tide to bloom and outcompete everything else,” Parsons said. “They are not the fastest growers, and they’re not the best competitors.”

Winds brought more than 20 tons of Saharan dust to the Americas last summer, but we’re waiting to see how much we’ll get this time around.

Rick Bartleson with the Sanibel-Captiva Conservation Foundation tracks water quality in Southwest Florida. He told us it’s not Saharan dust alone that feeds the sea sawdust. Other forms of air pollution can too.

“Like burning sugarcane or from exhaust from motor vehicles,” Bartleson said, explaining that other forms of air pollution can feed trichodesmium.