Why Florida Beaches Are Covered in Seaweed

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Long stretches of washed up seaweed are great for (most of) the beach's wildlife, but it's an annoyance to humans. Davy3 Photo/Shutterstock

There's nothing like taking a long stroll on a beach during a summer day and digging your toes deep into the slimy brown seaweed that has washed up on shore.

Wait. That's not right.

It is, however, the reality for some beaches in Florida right now. Wracks, or long lines of seaweed, have arrived on beaches, and residents and local governments are figuring out ways to cope with this inconvenience.

A Caribbean import

The seaweed, a brown variety called sargassum, is staking its claim to prime Florida beach spots after arriving from the Caribbean. There, the seaweed has been piling up high on the beaches, driving away the tourists. According to the University of South Florida's Optical Oceanography Laboratory, more than 1,000 square miles of the stuff has been detected in satellite photos of the area.

It's so bad that the Barbados government declared a national emergency June 7 to mobilize the Defense Force to aid seaweed removal efforts.

Regrettably, this isn't a new occurrence. Since 2011, sargassum blooms have been increasing. According to a report in Science Magazine, the source region of all this seaweed is surrounded by currents flowing clockwise from South America to Africa and back again. From January to May, however, the currents break down, and a west-moving flow sweeps the seaweed up along the Brazilian coast and into the Caribbean.

"All along the way, the sargassum is blooming and growing," James Franks, a marine biologist at the University of Southern Mississippi, tells Science Magazine.

Prior to 2011, this amassing of seaweed didn't occur, and scientists don't know why. There's a lot of "educated guessing," Chuanmin Hu, an oceanographer at the University of South Florida, told Science Magazine, but no definitive answers.

Among the guesses? Nutrients from the Amazon that spurred on the seaweed blooms, changes in ocean currents and increased iron deposits from the air.

Summertime nuisance in Florida

As for how the seaweed is getting to Florida, that's easier to explain. Ocean currents shift the seaweed into the Gulf of Mexico, and then it takes a ride on the Loop Current through the Florida Straits to the east coast of Florida.

Delray Beach, a small town north of Boca Raton, has seen tourists and residents attempting to wade through the seaweed, two feet high in certain spots, according to the Sun-Sentinel, and movers attempting to remove the seaweed from the shores.

"Because of all the seaweed, it's difficult to get all the kids out, with his huge blockade," Jacob Serody, a supervisor of a beach-geared summer camp, told the Sun-Sentinel. "A lot of the kids don't like the critters that live in the seaweed, the crabs, the shrimp. Swimming through it is a mess. You get scratched up, and you get sea lice."

But many of those critters do like the seaweed. It provides them with food, and with an influx of crabs and other small creatures comes a lot of birds looking for some extra helpings.

One sea animal that isn't a fan of this seaweed blockade is the the sea turtle. Newly hatched babies struggle to make their way to the ocean with all this seaweed in the way.

"When the hatchlings start hatching out, this could be a problem for them," Kirt Rusenko, marine conservationist at Gumbo Limbo Nature Center in Boca Raton, explained to the Sun-Sentinel. "It's a lot of material to crawl over if you're only a couple inches long."

Still, some human beachgoers that the Sun-Sentinel spoke to were more relaxed about the situation.

"It's nature," says Megan Pollit, a part-time resident of Delray Beach." You wouldn't pay extra for it, but it's not hurting me."