It’s hard to rattle a seasoned boater — most have seen it all before. Big water, bad weather, and boat trouble are just a few of the things things that create the grey hair on many a captain’s head.
But sometimes something so odd comes along that even boat captains tilt their heads.
The raft of brown seaweed is headed across the Caribbean towards the U.S. coast, seemingly with a beeline for the entire stretch between Key Largo and Fort Lauderdale. The seaweed is an algae species known as Sargassum. It grows in masses that remain afloat thanks to small air-filled sacs in their leaf structures. Floating masses are Sargassum are actually quite common, but 2023 will be different.
The blobs generally form between the Caribbean and West Africa in the Sargasso Sea (notice the name), at which point Atlantic currents push them west into the East Coast of North America. This summer, however, a unique combination of natrient-rich water, steady currents, and bad luck have created an epic mass.
While some scientists are trying to downplay the potential for a massive blob arrival in 2023, it appears this year’s Sargassum bloom is already clogging coastlines on the Eastern Seaboard and the island chains to the southeast. Small arrivals have already been recorded on several Florida beaches. The current mass is expected to span more than 5000 miles (8000 kilometers) from the coast of Africa all the way to the Gulf of Mexico. Locations as far away as Mexico have been told to prepare for up to three feet of Sargassum on their beaches.
In an interview with Scientific American, Brian Lapointe, an oceanographer at Florida Atlantic University, said the phenomenon is here to stay: “2018 was the record year, and we’ve had several big years since. This is the new normal, and we’re going to have to adapt to it.”
Not only do the masses wreak havoc on both commercial and recreational boat traffic around coastal areas, once it reaches shore it puts an enormous burden on local resources to collect and remove the rotting remains.
The 2023 mass has been dubbed the Great Atlantic Sargassum Belt, which is both apt and epic. According to Chuanmin Hu, an oceanographer at the University of South Florida in the Scientific American piece, the 2022 mass was the largest ever recorded in the Atlantic, accounting for over 22 million metric tons of seaweed. His team uses satellite from NASA as well as National Oceanic and Atmospheric Administration (NOAA) satellites to calculate their size. Hu is confident that the 2023 mass will be the largest yet.
As the blob has gained steam through the month of March, Hu said: “This month there should be more. There’s no doubt. Even in the first two weeks, I have seen increased amounts.” The masses typically peak in June and arrivals can occur as late as October.
Now, that’s not to say that Sargassum is a bad thing. It may be a scourge to boaters, but it’s a boon for the ocean. A bloom is essentially its own floating ecosystem, absorbing CO2 and nutrients while providing food and resources to marine wildlife. It’s only once it reaches the shore and beings rotting that it becomes a real nuisance.
Locations in central Florida like Fort Lauderdale, and as far south as Key Largo, are already seeing Sargassum blooms wash up on shore. Not only does this block beaches and disrupt tourist and recreational traffic, the rotting weeds also release hydrogen sulfide gas, which has the pungent aroma like rotten eggs. Repeated exposure can also irritate the sinuses and eyes, causing headaches, nausea, and breathing issues.
Lapointe says the total size of 2023 Sargassum bloom can’t be predicted yet. The warmer summer weather and the movement of the mass in conjunction with tides and currents will ultimately determine its final size.
“This is pretty early in the Sargassum season to see that much coming in, so I think that’s also fueling some of the concern about what’s to come,” Lapointe told Scientific American.
So what does this mean for boaters?
Adjusting boating trips and navigation routes in accordance with the location of the bloom(s). The Florida Department of Environmental Protection even has an Algal Bloom Dashboard where you can check the status and location of seaweed in your area. The University of South Florida’s Optical Oceanic Laboratory also offers Sargassum Outlook Bulletins every month.
Boaters will also be at an increased risk of clogging their impeller or propeller. Trying to go through one of the blooms is nearly impossible. Make sure you have the proper propeller to match your boat and know how to maintain it.
If you’re a jet boater, you’d also be wise to weigh the pros and cons of going out in a Sargassum bloom.