Seaweed concentrations doubled in size in the Atlantic to record tonnage but have since scaled back in an unusual early season decrease.
A raft of brown seaweed that collects naturally in the Atlantic Ocean between the Greater Antilles and Africa has grown large enough to be tracked by satellites in space.
The bloom doubled in size from December to January reaching 8.7 million tons, beating a previous record set January 2018 at 6.5 million tons. This, after December, saw concentrations double to record levels, a rate of consecutive monthly increases which hasn’t happened since the worst year back in 2018.
Now currents are drifting the seaweed toward beaches surrounding the Caribbean and Gulf of Mexico. Winds push the seaweed into cyclic annual seaweed invasions along the beaches which typically increase toward spring.
Strangely in March, the Sargassum abundance in the Central Atlantic actually decreased overall from January to February according to University of South Florida marine researchers who pioneered the use of remote satellite tracking.
This drop is uncommon until after the typical peak in July and the recent trend gives hope the current bloom may not be as bad.
Up until March, USF’s marine scientists say February had the second highest amount of Sargussum in the central Atlantic for the month behind the record set in 2018.
The brown seaweed can be common along Duval and St. Johns county beaches after easterly winds but it is more often a problem in south Florida where thick mats can carpet the shoreline due to the close proximity of the Gulfstream.
Excessive amounts of the brown macroalgae Sargassum seaweed has led to increasing beaching events.
The seaweed typically starts to decrease in July through August based on the historical record.
Sargassum gathers in the Central Atlantic northeast of Brazil and heads westward into the Caribbean Sea before moving into the Gulf and up the East Coast of Florida in the northward flowing Gulf Stream.
Yet 2023 is still expected to be a major Sargassum year and the billions of tonnes of seaweed floating in the Caribbean Sea continued to accumulate.
If you have a trip planned to the Yucatan or Caribbean expect to see the seaweed washing up on the shores. Researchers say the floating patch is still large enough to increase in March as it shifts through Caribbean Sea and Gulf of Mexico.
Some of it may migrate westward, creating beaching hazards along the way including small amounts showing around the Florida Keys in March.
The floating brown macroalgae provide critical habitat for marine life including crabs, shrimp, sea turtles, and fish that seek refuge around the floating clumps.
Too much can ensnarl marine life and trap toxins along the thick mats leading to piles of smelly decomposing algae along shorelines.
The problem has become such a nuisance over the years in the Caribbean that innovative cleanup ideas have sprung up including the Mexican Navy scooping it out of the ocean and others harvesting it as fertilizer or animal feed.