Environment

USF scientists lead a grant to better forecast sargassum blooms for coastal communities

WUSF | By Meghan Bowman

Published December 18, 2023 at 2:00 PM EST

A massive bloom of sargassum drenched coastlines of the island of Saint Martin in the Caribbean earlier this year. Now, the USF College of Marine Science is leading a grant to develop a forecasting system so areas can better prepare.

Coastlines in Florida and the Caribbean were saturated with a harmful algal bloom earlier this year.

The brown, moss-like algae is called sargassum. It's been around for hundreds of years in the North Atlantic.

But the 5,000-mile-long, 13-ton algal bloom from the western portion of Africa to the Gulf of Mexico was absent prior to 2011, according to oceanographer Brian Barnes.

Since then, scientists have been more closely studying what is now called the Great Atlantic Sargassum Belt because of its massive size.

Weather satellites allowed them to follow the blooms in the open ocean. But as the algae approached a shoreline, scientists lost tracking capabilities.

Barnes is with the University of South Florida College of Marine Science, which is leading a five-year, $3.2 million grant to develop a forecasting system to help change that.

Barnes said the grant will help "bridge that gap" between tracking the sargassum in the open ocean and land. Scientists will be able to pinpoint coastal communities that will be impacted by the algae.

"We can say this particular patch is going to be a factor affecting this particular beach within a couple of days, rather than just saying, 'there's a ton of sargassum out there and it's impacting these regions,'" he said.

The grant gives scientists the ability to use higher-resolution sensors to narrow the scale of tracking the algae from kilometers to meters. When a satellite passes, they will collect the data, and then confirm it with boats and drone footage.

In the open ocean, the sargassum blooms float on top of the water and provide an essential habitat for marine life. However, once it reaches the coast, it causes issues for people and marine life.

"The blooms that come on shore are so massive that they can't be kind of just broken down by foot traffic or broken down into the normal ecosystem," Barnes said. "It becomes just an inundation that smothers the stuff offshore, it can smother the beach, and as it decomposes, it causes even more problems."

The decomposing algae releases hydrogen sulfide, a gas that smells like rotten eggs and can be harmful to humans. It can also promote hypoxia, an area of low to no oxygen that can kill fish and marine life.

Barnes said ideal temperature and light conditions during the summer months cause the sargassum to grow. It then wanes as the weather cools down.

Other USF marine science researchers have identified nitrogen and phosphorous as two of the nutrients that are driving factors in the bloom's growth.

USF will receive about half of the funding, with the remainder going to Florida Atlantic University, the Caribbean Coastal Ocean Observing System, NOAA Atlantic Oceanographic and Meteorological Laboratory, and the U.S. Virgin Islands Department of Planning and Natural Resources.

"We have a focus in Florida as part of the project, but the other half of the project is focused on Puerto Rico and (the) US Virgin Islands," Barnes said. "Those areas also have not received any kind of have funding before and so this is expanding that reach to some more regularly underserved areas as well."