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WHAT’S THE DEAL WITH THE SARGASSUM ‘BLOB?’
Defining The Details As The Macroalgae Approach The Keys
Massive offshore weedlines are the stuff of Keys bluewater anglers’ dreams. But though it’s too early to say for sure, the latest mass approaching the island chain is one they might wish went elsewhere.
By now, most have heard about the massive “blob” of sargassum – an umbrella term for hundreds of species of brown algae – approaching the Keys. Stretching nearly all the way across the Atlantic Ocean, with an estimated current mass of 13 million tons, it may undoubtedly prove problematic for the Keys in the coming months, as it has done most notably in the summers of 2018 and 2022.
But regardless of the picture painted by other reports, according to those who study the macroalgae, it doesn’t mean that thousands of miles of weeds are about to wash up on Keys beaches all at once. And it’s still too early to predict the final picture for the island chain when all is said and done.
This week, Keys Weekly was fortunate to sit down with renowned Florida Atlantic University researcher Brian Lapointe and Florida Keys National Marine Sanctuary research coordinator Andy Bruckner to better understand what’s driving the algae, and what the Keys can expect from here.
What is “the blob?”
First things first: This isn’t a onetime traveling mass that appeared out of nowhere, and it’s entirely separate from red tide, although the two can cause similar effects.
The Great Atlantic Sargassum Belt is the world’s largest recurring macroalgae bloom, often extending from the west coast of Africa to the Gulf of Mexico across the southern edge of the Sargasso Sea. With air bladders that help it stay afloat and a rough, intertwining shape that helps keep large patches together, the massive floating habitat is a hotspot for biodiversity. In addition to providing vital food and protection for fish, mammals, marine birds, turtles, crabs and more, it serves as a nursery for mahi mahi and jack species.
The belt’s annual bloom usually begins in the winter and spring months, typically peaking in early to mid summer. Its distribution throughout the Atlantic Ocean and Caribbean Sea is largely driven by currents and ocean circulation.
“The ‘blob’ moves into the Caribbean … and some of that is carried up into the Gulf, and some of it is carried by the Gulf Stream around past the Tortugas along the Florida Keys up to Miami,” Bruckner said.
What’s the issue?
While the floating version of sargassum provides a critical offshore habitat, piles of the algae on beaches and in nearshore waters can prove problematic.
“Dead zones” can replace vital nurseries as large quantities of sargassum create anoxic conditions that threaten marine life. In shallow water, degrading algae masses can kill plants and animals on the seafloor, while hydrogen sulfide gas released by the decomposing organism is a toxic eye and respiratory irritant. As if that wasn’t enough, it smells like rotten eggs, an unwelcome scent for the throngs of tourists who frequent Florida’s beaches each year.
“The biggest thing is that if there is a lot of this material that comes into the shoreline, there should be recommendations that people aren’t swimming in that water,” said Bruckner.
Unfortunately, disposing of the piles of smelly sargassum when it washes ashore isn’t as simple as scooping it all up and using it for fertilizer.
Visit keysweekly.com for the full story.
Jerry and Mary Lou Wilkinson dressed in outfits for the Indian Key Celebration held in April 2022. Jerry passed away at the age of 94 on March 16. KEYS HISTORY & DISCOVERY CENTER/Contributed
While it serves many important ecological purposes, excessive quantities of the brown macroalgae known as sargassum can pose ecological and human health risks. KEYS WEEKLY FILE PHOTO

The Sargasso Sea is bordered by four currents that form an ocean gyre. The Great Atlantic Sargassum Belt typically runs along the sea’s southern edge and is pushed westward by an equatorial current. WIKIPEDIA/Contributed
Keys Marine Worker Killed After Crane Falls Into Water
A 29-year-old Homestead man died on March 21 after a construction crane fell over in Key Largo.
According to the Monroe County Sheriff’s Office, Jose Eduardo Reyes Ponce was an Upper Keys Marine Construction worker who was working with a crew to install dock pilings in the water. The workers were in the area of Mutiny Place when the crane fell into the water around 3:30 p.m. Ponce was pronounced dead at the scene. Foul play does not appear to be a factor in the incident. Autopsy results are pending. The sheriff’s office and OSHA are investigating the incident.
— Keys Weekly staff report.