What to know about the sargassum seaweed blob hitting Florida : NPR
It used to be that the conversation about subtropical marine life was centered on decline: the death of coral beds, the decreasing variety of sea grass, the disappearance of fish.
But for now, it’s an overabundance that’s hard to miss. From Montego to Miami, an influx of algae called sargassum is leaving stinky brown mats on what was once a prime tourist sand. It is the most sargassum researchers have monitored this early in the year.
Deciding what to do with it is becoming more challenging the more we learn about it – and it’s inspiring some entrepreneurs to rethink removing sargassum altogether.
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Wait, what is sargasso and why is it blooming?
Sargasso is a type of floating, rootless seaweed that gathers in islands and swims around the ocean.
Patches of sargassum have been spotted in the Atlantic Ocean for centuries, but since 2011, a monstrous 5,000-mile-long belt of algae has flowed annually between the Gulf of Mexico and the mid-Atlantic.
The density of clusters in that belt continues to increase, possibly because modern agricultural techniques are sending more and more nutrients down and into the ocean.
This April alone, sargassum levels in the Caribbean Sea reached a new record, with the overall belt growing to around 13 million tonnes, according to bulletin from the University of South Florida Optical Oceanography laboratory.
And peak flowering season is still days away, with a peak likely to hit in June or July. If the past is any precedent, the size of the bloom could double in the next month, says Brian Barnes, a researcher in USF’s College of Marine Science.
It is hard to predict what this could mean for the beaches, especially in the eastern Atlantic where persistent clouds are obscuring the satellite views that Barnes and his team rely on.
But already, sargassum bugs are increasing, with the southern regions of Hispaniola, Jamaica and Puerto Rico seem likely to be the most affected.
Ignoring it can be dangerous – and smelly
Once ashore, the sargassum is not only unsightly or cumbersome to swim around – it stinks. The seaweed begins to decay within 24 hours of hitting the shore, releasing hydrogen sulphide and the smell of rotten eggs.
There is some evidence to show that those gases can cause nausea and headaches or worsen respiratory problems. In 2018, doctors on the islands of Guadeloupe and Martinique reported more than 11,000 cases of “acute sargassum toxicity” during an eight-month period of intense beach accumulation, Reuters reported.
But even the scent alone can be expensive.
Take the Florida city of Key West for example. Public Information Officer Alyson Crean says Key West isn’t even a beach town, with the largest public beach stretching only about half a mile in length.
But a 2020 analysis found that 1 in 10 tourists say they would either cancel or reschedule their trip to Key West if they knew sargassum was present. A bad sargasso year could leave a $20 million dent in Key West’s $2.4 billion tourism industry, leading to the loss of about 300 jobs, according to the report.
Sargassum removal can also come at a high price
In places like Key West, removing sargassum from the beach is about the only option to deal with it.
“Strict environmental laws say sargassum can’t be taken out of the water,” says Crean. And installing containment barriers in the water would be “a battle,” she says, because it would take “a long time” to get any state-approved permits.
Closer to land, sargassum can also pose a threat to local wildlife, choking out coral reefs and sea grass. But in the open ocean, it can store carbon, the main driver of climate change. It can also serve as a prime habitat for sea turtles, fish and crustaceans.
So Key West waits for the algae to wash ashore. On summer mornings, a team of volunteers walk the beaches to check for captured turtle hatchlings or signs of new nests, Crean says. After all, a contracted company uses heavy equipment to ride the sargassum off the beach.
It’s a routine that costs the city about $1 million a year, and Key West is prepared to pull more funding from a reserve stash if needed, Crean says.
Other coastal localities are following suit. In nearby Miami-Dade County, which spent more than $3.9 million on sargassum cleanup last yearis asking the state for an additional $2 million.
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What happens to all that sargassum when it is removed from the beach?
Removing sargassum is just one challenge; disposing of it is another entirely.
Crean says the Key West company contracts to give sargasso to farmers to use as fertilizer. In Mexico, it is truck inland to rot in the junglereports National Geographic.
But options for processing or decomposition of algae it may become more expensive as the field of sargassum study grows.
Researcher Brian Lapointe told NPR last month that new research suggests the decomposition of sargassum can leave heavy metals in its surrounding environment.
One study that examined sargassum along the beaches in Mexico found that 86% of the samples had arsenic levels that were higher than the UN limit for livestock feed – one idea of repurposing that was explored earlier.
So can we do something?
Some companies are still trying to be creative, experimenting with turning sargassum in biofuel, construction material or even medicinal products.
One of the most promising ideas is a double-edged sword: drown Sargasso to prevent it from releasing carbon.
UK startup Seaweed Generation is building an autonomous robot that can intercept patches of sargassum close to shore, drag them back to the open ocean and force them to sink to a depth of 1,000 meters, and effectively carbon sargassum holds are captured.
“It’s a bit like an algae Roomba,” the company’s CEO, Paddy Estridge, told NPR. “It goes through the water very, very slowly and, a bit like Pac-Man, it collects algae.” It then dives down and dissolves the biomass about 200 meters deep, where the air pods that keep the sargassum afloat emerge, sending the mass into a watery grave.
The so-called AlgaRay is still in pilot phases, financed by venture capitalists. But if successful, a complete model could be ready to operate next year, and dive up to 15 tons of sargassum in one trip.
Until then, the best option for an individual concerned with sargassum may be patience – or avoidance.
Barnes, the researcher who tracks the sargassum with satellite images, says there’s no point in, say, canceling your beach vacation, even if you know the local government isn’t he is doing daily cleaning.
“The effects are very, very local,” he said. “You’ll see an incredible amount of sargassum in one small bay, but if you look ahead in the next bay, there is absolutely no sargassum.”
If you’re really worried, however, he suggests you might take a cue from the researchers, keeping an eye on it where the buds are creeping close to the shore.