Robyn Wishna / A mat of sargassum bobs in the water off the coast of Fort Lauderdale just north of the Port Everglades inlet on April 2, 2023.

USA - Food, fertilizer, fuel? The hunt is on for solutions to the Caribbean’s exploding seaweed problem

The floating brown seaweed known as sargassum has exploded in record-setting mass throughout the region. There is increasing commercial and research interest in developing ways to put it to use.

Most of the troubles plaguing the subtropical waters of Florida and the Caribbean revolve around disappearing marine life: coral reefs, fish populations, sea grass beds. It’s decidedly the opposite case with sargassum, the floating brown seaweed that has exploded in record-setting mass throughout the region.

Nothing can stop the stinky brown mats from carpeting beaches and shorelines through this summer: Sargassum quantities hit record levels in the Caribbean in April, according to researchers at the University of South Florida, and the scientists wrote in a May 1 report that sargassum totals are only “expected to increase over the next few months, with impacts of beaching events in the Caribbean Sea and Gulf of Mexico worsening accordingly.”

The problem, the researchers wrote, is especially acute along the southern coasts of Hispanola, Jamaica and Puerto Rico. So there is increasing commercial and research interest in developing ways to put such an abundant and seemingly sustainable resource to use.

In Jamaica, for instance, one company started out converting sargassum to fertilizer or animal feed and has since turned to converting it into biofuel. Another company is farming a different kind of seaweed that produces agar, a jellylike substance used in a lot of health food products. There is regional and even global interest in determining whether seaweed farms and sargassum also could act as a “carbon sink” to offset greenhouse gas emissions.

Seaweed is, at least technically, edible. Some species of the floating algae have long been used in Asian cuisine and, when dried, in medicine. And while it’s not been commonly consumed in the Caribbean, it has been eaten by Jamaican fishers – at least in times of desperation.

“I’ve been at sea with other fishermen, stranded for days, starving. We happen on a big floating mass of grass and I witnessed men eat that grass like food. Men that are alive today to tell the tale,” said Romain Betty, who lives in the coastal town of Manchioneal. His story drew nods of agreement from others around him.

But recent research show sargassum comes with health risks and uncertainties that likely will keep it from winding up as part of anybody’s diet, said Jodiel Ebanks, beaches coordinator at the National Environment and Planning Agency (NEPA) in Jamaica.

“We suggest a cautionary approach when dealing with sargassum due to the levels of arsenic and other heavy metals found in it,” she said. While it might sustain fishers for brief periods, there are too many unknowns at the moment to say what the impacts might be over the long term if used in the food supply – at least without considerably more study.

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