It sounds like the stuff out of a horror film: a giant, blob-like blanket of seaweed that is so big it can be seen from outer space.
The over 8,000 kilometre-wide brown glob of seaweed, known as the Great Atlantic Sargassum Belt, is not new — but it is on the move and could potentially wreak havoc on beaches in Florida, Mexico and the Caribbean this summer.
Scientists have claimed this year’s bloom of sargassum is the largest ever recorded.
The sargassum currently floats between the Gulf of Mexico and the shores of West Africa. In open waters, sargassum — which is a form of macroalgae — is mostly harmless and serves as reliable habitat for ocean life. When it washes up on shore, however, not only is sargassum unsightly, but it also reeks and worsens air quality as it decomposes.
The Smithsonian claimed hordes of sargassum usually make landfall in May, then peak in June and July. As sargassum piles up and rots on beaches in Florida, Mexico and the Caribbean, it releases toxic hydrogen sulfide into the air — a gas that smells of rotten eggs and may cause respiratory and neurological issues in humans. Sargassum can also smother mangrove habitats, reduce oxygen levels in water, impact critical infrastructure and stifle coastal tourism.
A 2022 study claimed women living in coastal areas swamped with sargassum had an increased risk of serious pregnancy complications.
Last year, the U.S. Virgin Islands declared a state of emergency as a result of “unusually high” levels of sargassum piling up on the territory’s shores.
Scientists believe hundreds of tons of sargassum could crowd once-accessible beaches this year.
NBC reported some beaches in Key West, Fla., are already overloaded with sargassum. Parts of Mexico have braced for nearly one metre of the muck to crowd beaches this week.
It is not yet known exactly why or how the sargassum appears to be growing year after year, though the climate crisis is a probable cause. The New York Times reported sargassum growth is likely seasonal and has to do with the discharge of major waterways in the Congo, Amazon and Mississippi rivers. Runoff from these bodies of water feeds the sargassum as it grows. Fossil fuel emissions and carbon monoxide released as a result of deforestation may also contribute to the blanket’s growth, the New York Times claimed.
Removing sargassum from beaches requires ample manpower and can be costly, but there’s another issue too. Even when sargassum is cleaned up and collected, the question of what to do with the seaweed remains. Though some scientists have suggested using sargassum as fertilizer, this may be dangerous as sargassum contains arsenic, which could infiltrate the food chain. Composting sargassum would result in the same dilemma: arsenic potentially leeching into groundwater sources. Processing the minerals in sargassum is not cost-effective.
The Guardian reported that select scientific teams are experimenting with sargassum as a means to purify water, as a building material or as a biofuel. Others have suggested sinking it to the bottom of the seafloor.
In 2018, after a then-record surge of sargassum swallowed beaches, some resorts saw tourism decrease, including the Riviera Maya hotels in Cancún which experienced a nearly three-per-cent dip in occupancy rates. According to National Geographic, resorts have been forced to spend thousands of dollars a day paying for intensive labour to clean up beaches. Others have spent millions to purchase specialized boats and equipment to create offshore sargassum barriers.