“Massive seaweed blob invades Florida beaches.”
“Huge, smelly snake of seaweed headed toward the Caribbean.”
Though the headlines sound like something from a 1950s horror movie, sargassum — a type of seaweed — is a naturally occurring plant that, under normal circumstances, shouldn’t be a major cause of concern for beachgoers.
Does this year’s sargassum have the potential to sour your seaside vacation in the coming months? TPG spoke with oceanography experts to find out.
What is sargassum?
Sargassum is a large, brown seaweed — the common name for various species of marine plants and algae — that floats along the ocean’s surface.
In healthy amounts, sargassum is a critical habitat for sea creatures. Animals like small fish, crabs, mollusks and even young sea turtles hang out around patches of sargassum for shelter and because the smaller residents provide a food resource for the larger ones.
Sargassum is neither destructive nor harmful under normal circumstances, even when left unattended on beaches. When it accumulates in massive amounts, however, it can have a negative impact on the ecosystem and local economies.
Should you be concerned about sargassum in 2024?
Technically referred to as the Great Atlantic Sargassum Belt, the annual sargassum bloom isn’t actually one continuous blob. Some patches can be miles long and tens of meters wide, while others can be more scattered and dispersed; together, they cover an area “several hundred miles wide across the Atlantic,” according to Sea Education Association professor of oceanography Jeffrey M. Schell.
If you recall, 2023 saw a record sargassum bloom measuring close to 200% larger than what was present in 2022. The larger bloom resulted in record levels of sargassum washing up on beaches in the Caribbean and the Gulf of Mexico. When conditions were at their worst, affected beaches could have meter-high sargassum piles covering the entire beach.
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When sargassum is as thick and plentiful as last year, it can cause major trouble both at sea and on the beach.
“Large amounts of sinking sargassum can smother corals and seagrasses, while rotten sargassum smells bad and may cause respiratory problems to humans,” Yuyuan Xie — an oceanographer in the Optical Oceanography Laboratory at the University of South Florida whose laboratory works with the satellite-based Sargassum Watch System — told TPG.
“On beaches, large amounts of rotten seaweed are harmful to animals and humans because they attract insects, harbor bacteria and smell quite bad as it decomposes,” Xie said.
Based on satellite imagery from a quarterly bulletin provided by The Centre for Resource Management and Environmental Studies at The University of the West Indies, Barbados, there is about 40% less sargassum visible in the Atlantic Ocean than there was at this time last year.
“There is definitely sargassum out there, and it’s already starting to make its way into the Eastern Caribbean,” Schell said. “So even though the bloom is about 50% smaller than last year, those beaches in the Eastern Caribbean are probably seeing a fair amount of sargassum wash on the shore, though not as much as they had this time last year.”
Xie also noted that this year’s outlook is more favorable than last.
“So far, this year is better than last year, and this situation is likely to continue in the next few months,” Xie said. “Florida will be largely free of sargassum until at least late May.”
Should you cancel your upcoming beach vacation?
First and foremost, not every beach in a given area will be affected by this pernicious seaweed. Winds, currents and tides help determine where exactly sargassum will accumulate and wash ashore.
Although this year’s predictions are mild to moderate, some beachgoers will still see sargassum during their vacation.
“For islands in the Lesser Antilles, the windward sides are more likely to see some of that sargassum,” Schell said. “But it’s still at a medium level compared to the scale that they have been.”
Beaches along the eastern Caribbean Sea are already seeing some sargassum, but the southeast coast of Florida and the Florida Keys look to be in the clear until May, according to Xie.
While there’s still the possibility of sargassum on the beach during your vacation, the experts we spoke with promised this is not a reason to cancel your trip. Typically, not all beaches in an area will be affected, meaning you always have the option to pop over to a nearby beach.
“You should still go on vacation,” Schell said. “There may be some sargassum in the next couple of months, but not enough that it should be getting in your way.”
It may be difficult to determine which beaches will be affected and when, but an entire city or beach community should not be inundated with sargassum to the point that you can’t enjoy some fun in the sun. Be prepared to visit a variety of nearby beaches and plan a few alternate activities, like visiting an aquarium or botanical garden, as a backup plan.
What can be done to mitigate the problem?
Affected beach destinations also have cleanup initiatives to help keep their beaches looking beautiful and inviting to visitors.
“The local management agencies typically remove large amounts of seaweed from the beach before it decomposes,” Xie said.
Experts are looking into several methods for collecting and cleaning up sargassum before it becomes a headache for beach communities and beachgoers.
“We’ve yet to find a silver bullet,” Schell said, “but sargassum can be collected at sea or on the beach. It is a habitat, though, so we have to be mindful and respectful of the animals who call sargassum home.”
The majority of current cleanup efforts focus on removing sargassum from the beach after it washes ashore; they use tools as simple as rakes and wheelbarrows in addition to more futuristic methods like beach-cleaning robots.
The issue then becomes what to do with it. Many beaches bury the sargassum under the sand to keep it from being a nuisance, but some creative cleanup initiatives are happening as well.
Fort Lauderdale has instituted a seaweed composting program that transforms seaweed into soil that can be used for city planting projects, saving the city tens of thousands of dollars annually.
The Rum & Sargassum program in St. James, Barbados, is creating an inexpensive, alternative fuel source for vehicles using locally sourced waste products like rum distillery wastewater, sheep manure and sargassum.
According to Schell, these innovations (and those that are still being developed) are a boon to cleanup efforts and the bottom line.
“The money involved in cleanup and the impact on local fishing activity and tourism has a tremendous economic impact on beach communities,” he said. “Any economic return found by creating a product it can be turned into can make a big difference.”
What’s in store for this year’s sargassum bloom?
Because sargassum undergoes seasonal growth cycles, some years are worse than others, and researchers are still trying to fully understand these cycles. They have observed that this year’s bloom may largely die off before it washes ashore because water temperatures are creeping higher.
“In the North Atlantic, the water is already two degrees warmer than we should be this time of the year,” Schell said.
Last year also saw warming water temperatures, leading the sargassum bloom to die off in June. Schell is predicting a similar cause and effect this year.
“My guess is that the bloom is going to die early. The temperatures are going to warm up too fast,” he said. “We are already seeing water temperatures around the bloom hit 28 degrees Celsius (82.4 Fahrenheit), and the bloom will likely break up when we hit 30 degrees Celsius.”
Xie’s data backs this up. In the 2024 sargassum bloom outlook from the University of South Florida College of Marine Science, Xie and his colleagues noted that the total sargassum bloom has already decreased from 9 million metric tons in February to about 6.5 million metric tons in March.
They interpret this decline to mean that while levels are higher this year and last than in previous years, the coastal regions in the western Caribbean Sea should receive small to moderate amounts of sargassum by late April or early May; the southeast coast of Florida (including the Florida Keys) shouldn’t see much Sargassum until late May.
Bottom line
Shook up about sargassum? Don’t be.
Though some beaches are seeing sargassum wash ashore, levels are already proving to be much lower than the record-breaking amounts in 2023. Beach communities are well practiced in cleaning up seaweed, and researchers like Schell and Xie are hard at work understanding sargassum and how to minimize the problems it can cause.
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