Giant blob of seaweed expected to reach Florida – 03/17/2023 – Environment

For much of the year, a huge brown “blob” floats, relatively harmlessly, across the Atlantic Ocean. Its tendrils provide shelter and breeding grounds for fish, crabs and sea turtles. Spanning thousands of kilometers, it is so large that it can be seen from outer space.

But scientists say that in the coming months, the blob — a tangled, floating mass of a type of algae called sargassum — is expected to reach the coast of Florida (USA) and other points along the Gulf of Mexico.

Scientists say the bubble will begin to fester, emitting toxic fumes and littering the region’s beaches during the busiest summer months.

Seaweed, which can also cause pollution and threaten human health as it decomposes, has already begun spreading along the coasts of Key West, Florida.

In Mexico, “excessive” levels of the algae were recorded last month on beaches south of Cancun. Photos and videos from the area show sunbathers wading through brown mud along otherwise gleaming beaches.

“You can’t go in the water,” said Leonard Shea, a traveling YouTuber, in a recent video in the resort town of Playa del Carmen, which showed waves crashing under a thick blanket of seaweed. “Not a pleasant experience.”

Sargasso—a type of macroalgae that is naturally abundant in the Sargasso Sea in the Caribbean—has long been seen floating on mantas in the North Atlantic. But in 2011 scientists began seeing extraordinary accumulations of algae that stretch across a belt from West Africa to the Caribbean Sea and the Gulf of Mexico, according to a 2019 study.

The immense bloom continued to grow almost every year.

Although scientists are still trying to understand exactly why and how the mass, known as the great Atlantic sargasso belt, is expanding, it appears to be seasonal — coinciding with the discharge of major waterways, including the Congo, Amazon and and Mississippi.

Runoff from these sources helps fuel the bloom with nitrogen and phosphorus, said Brian Lapointe, a professor and researcher at Florida Atlantic University who has spent most of his career studying sargasso. Emissions from fossil fuels and the burning of biomass — such as trees after deforestation — also produce nutrients, he added, that may be helping the algae grow.

“These blooms are getting bigger and bigger, and this year looks like it’s going to be the biggest year on record,” Lapointe said.

In January, scientists measured the largest bloom recorded that month.

“It’s too early to see so much, so soon,” he added. “It just doesn’t bode well for a clean beach summer in 2023.”

According to the National Oceanographic and Atmospheric Administration (NOAA), seaweed blooms will continue to disturb Caribbean waters through mid-October.

While floating seaweed can benefit marine animals by providing shade and shelter, the problems start when it washes ashore. As the sargasso begins to die, it degrades water quality and pollutes beaches, scientists say. It can also smother vital mangrove habitats and suck oxygen out of the water. Decomposing algae also release hydrogen sulfide, a colorless gas that smells like rotten eggs and can cause breathing problems in humans.

Last summer, the US Virgin Islands declared a state of emergency after “extraordinarily high amounts” of sargassum accumulated on its shores, affecting a desalination plant on St. Croix.

And in 2018, after a mass explosion that spread some 5,500 miles across the Atlantic Ocean, doctors on the Caribbean islands of Guadeloupe and Martinique reported thousands of cases of “acute” exposure to hydrogen sulfide, according to a study published in that journal. year.

In the past, besieged coastal towns have resorted to various measures to get rid of sargasso: in Mexico, the navy has been enlisted to scoop the seaweed out of the ocean and sweep up the country’s beaches. However, some businessmen have proposed turning the algae into animal feed, fuel or building materials.

But Lapointe, the researcher-professor, warned that anyone experimenting with new uses for seaweed should be extremely careful: Sargasso contains arsenic, which, if used in fertilizers, could move up the food chain.

The most immediate threat, however, is to tourism.

“It’s having catastrophic effects,” he said.

^{Translated by Luiz Roberto M. Gonçalves}