Giant seaweed blob visible from space en route to Florida

An aggregation of seaweed so large it is visible from space is approaching Florida’s Gulf coast at a record pace. 

The blob, which contains over 20 million entangled tons of a brown, buoyant seaweed called sargassum, harmlessly floats through the Atlantic Ocean for the majority of the year. Sea creatures like jellyfish, sea turtles and crabs reside inside the bloom, using it for shelter and nutrients. 

However, for humans, the algae bloom is anything but a harmless source of shelter and nutrients. As it inches closer towards Florida, which it does on a seasonal basis, scientists fear the worst.

Biggest algae bloom on record

“These blooms are getting bigger and bigger and this year looks like it’s going to be the biggest year yet on record,” Brian Lapointe, a professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute. “This is quite early to see this much, this soon. It just doesn’t bode well for a clean beach summer in 2023.”

Piles of seaweed usually begin to appear along the shores of South Florida in May, Lapointe added, but it is March now and beaches in the Key West are already filled with algae.

The seaweed does not just clog beaches, making them near impossible to enjoy and unpleasant to look at. Proximity to sargassum has also been proven to lead to harmful health effects. When washed ashore, sargassum decomposes, producing hydrogen sulfide. In addition to emitting a putrid stench, hydrogen sulfide irritates the eyes, nose, and throat, hindering one's ability to see and breathe. 

While many news sources are reporting that the sargassum blob will impair the health of a sizable fraction of the population, the Florida Department of Health says otherwise. According to them, if one is exposed to hydrogen sulfide for an extended time frame in an enclosed space with little-to-no air flow could sargassum affect your long-term respiratory health, meaning only hyper-specific work environments near the beach will see negative exposure. Hydrogen sulfide levels in less-cramped areas with ample airflows, like the beach, are not expected to be high enough to cause health defects.

In addition to hurting Floridians’ health, sargassum blooms may decimate Florida’s economy as well. The blooms destroy human boats and machinery by trapping them in an inescapable, immobilizing entanglement of seaweed. Piles of seaweed on the beach also make Florida a less desirable tourist destination, which will suck funds from the state, adding onto the costs of manually removing the seaweed from the beaches.

“Even if it’s just out in coastal waters, it can block intake valves for things like power plants or desalination plants, marinas can get completely inundated and boats can’t navigate through,” said Brian Barnes, an assistant research professor at the University of South Florida’s College of Marine Science. “It can really threaten critical infrastructure.”

The Great Atlantic Sargassum Belt

The blob of seaweed, which many call the “Great Atlantic Sargassum Belt,” increases in size each year. Scientists have found that climate change and other man-made phenomena are infusing rivers that feed into the Atlantic with nitrogen and other nutrients that feed the sargassum blooms. 

“You have the Congo, the Amazon, the Orinoco, the Mississippi – the largest rivers on the planet, which have been affected by things like deforestation, increasing fertilizer use and burning biomass,” said Lapointe. “All of that is increasing the nitrogen concentrations in these rivers and so we’re now seeing these blooms as kind of a manifestation of the changing nutrient cycles on our planet.”

Barnes added: “As far back as we have records, sargassum has been part of the ecosystem, but the scale now is so much bigger. What we would have thought was a major bloom five years ago is no longer even a blip.”