Seaweed, a frequent Florida visitor (only more of it these days)

Ernie Settembre with
seaweed catch
 1948/State Archives
of Florida

By Jane Feehan

South Florida beachgoers climb over smelly seaweed clumps during summer 

months as they look for a spot to sit. Swimmers may have to maneuver around this annoying plant, a form of algae. Long-time residents know this is a seasonal occurrence. A mix of history with a pinch of science may frame the April 2023 media hype about it (it’s always the worst ever, right?).

Seaweed is called sargassum because it’s usually produced in the Sargasso Sea, a body of water—an area not bordered by any land—within the Atlantic Ocean south of Bermuda to the equator. Sargassum is composed of 50 percent nitrogen, 20 percent phosphorous and a mix of iodine, calcium, magnesium, iron, sodium and other minerals. This algae can support sea urchins (an animal, class Echinoidea), tiny shrimp and other small animals; it can be perilous for larger animals who may get tangled up in its mass. 

The bloom of 2023* may be the largest ever with a 5,000-mile-wide patchwork of clumps (not a blanket). According to Harvard University the last record was set in 2018. The BBC (British Broadcasting) said 2020 set a record. 

The U.S. National Oceanic and Atmospheric Administration claimed 2011 was the turning point for the preponderance and rate of growth of these algae blooms because of climate change (sigh). Sargassum or seaweed, a rootless, stemless, leafless mass, has washed up on Florida beaches via high winds and rough seas for thousands of years. Some scientists say today’s rate of growth—a mass can double its size in 10 days—is tied to pollution. Nitrate fertilizers, human waste or sewage and industrial waste run into the Gulf of Mexico via the Mississippi River and into the Atlantic Ocean from the Amazon River, fueling such growth.

Seaweed troubles have claimed SOFLA headlines for decades. In 1953, long-time residents said the nuisance was the worst they had seen in years. “We’re up to our necks in seaweed,” read one news account about the problem in Hollywood. An estimated 1,000 tons had washed ashore. Work gangs in Deerfield Beach cleared the mess up daily one summer. 

The solution, a limited one, was to bury seaweed at the beach but it takes two years to decompose. Newspaper gardening columns promoted the use of seaweed as fertilizer after washing away the salt water, then letting it dry and decompose, a long process. Others claimed it would be a good source of food. It proved not to be – not enough protein.

The city of Fort Lauderdale devised a solution during the late 1950s. The maintenance crew of what's now known as the Public Works Department hooked up a tractor to a hopper. People came from all over to see the seaweed remover. Fort Lauderdale was the “only place in the world with such a machine.” Removal was a tricky process. If the seaweed got too dry, they’d pick up too much sand.

Photos from the Fort Lauderdale News in 1976  showed a seaweed inundation stretching from the water's edge at the beach to State Road A-1-A. Another significant event occurred in 1981. In November that year, extraordinarily high winds and seas during a king tide scooped both sand and seaweed off the beach to the west side of A-1-A near Sunrise Boulevard. The road was impassable for a brief time (yes, a flooding beach road in 1981!).

Seaweed was so bad in 1991 that Florida Power and Light shut down two of its power plants (Crystal River and Vero) after sargassum clogged cooling systems.

Sargassum season runs from about March through October. Meanwhile, I have a call into the city of Fort Lauderdale to find out what machine they now use to clean the beach and where they dump the stuff these days. I may get a faster response from a lifeguard.

*July 4, 2023 Sun-Sentinel update: the super-sized  record breaking field of seaweed bloom has diminished by 75 percent. So is the news about it.

Sources:

American Scientist, Vol. 101, No. 6, Nov-Dec 2013

Fort Lauderdale News, June 13, 1953

Fort Lauderdale News, June 14, 1953

Fort Lauderdale News, April 24, 1962

Fort Lauderdale News, June 24, 1965

Fort Lauderdale News, Jan. 1, 1970

Fort Lauderdale News, April 12, 1970

Fort Lauderdale News, April 27, 1970

Fort Lauderdale News, Dec. 13, 1976

Fort Lauderdale News, Nov. 15, 1981

South Florida Sun-Sentinel, Aug. 15, 1991

South Florida Sun-Sentinel, April 6, 2023

 Tags: Florida seaweed, history of Fort Lauderdale, Broward County history