Record levels of seaweed blooms washing into Florida

A look at the likelihood of Sargassum seaweed reaching North Florida

An abundance of decaying Sargassum seaweed along a beach in Ft. Lauderdale, FL clumps on the wrack line. (Mark Collins, WJXT)

This summer is seeing the most seaweed ever on record in the Atlantic basin, and it is blanketing the beaches with numerous problems.

Sargassum seaweed washes up seasonally along our beaches, especially after a period of southeast winds blow it in from the ocean.

The floating brown macroalgae is a beneficial habitat for marine life including crabs, shrimp, sea turtles and fish that seek refuge around the floating clumps.

The concentration has exploded in the tropics and now covers many central and south Florida beaches with piles of smelly decomposing algae. The record abundance this year makes for a dire situation along the coast for beachcombers.

Mats of floating Sargassum provide a habitat for marine life and can trap sand on the beach, however too much of it can be a problem for beachgoers. (wjxt)

The Florida Department of Health says the seaweed itself cannot harm you, however, tiny sea creatures that live in Sargassum can irritate a person’s skin.

Scientists believe the unprecedented amounts of Sargassum are due to both natural and human problems arising from nutrient loading in the Amazon River, warmer ocean temperatures along with African dust all fostering record bloom concentrations.

Historical records show the seaweed begging accumulating in the Central Atlantic at the start of the year before drifting westward in the following months toward the eastern Caribbean Sea.

It didn’t take long for it to reach the Gulf. It arrived about one to two months earlier in April this year when it first showed up around the Mississippi River Delta.

The spring accumulations in the northern Gulf surpassed the historical high set in 2018 amassing 14 million tons in April 2022.

But it continued to grow exceeding all previous major bloom years by May and the latest report from the University of South Florida Sargassum Watch System shows 24.2 million tons in the water in June 2022, setting a new historical record.

The USF maps show Sargassum abundance, with warm colors representing high abundance. June has surpassed the previous record set prior to 2019.

Based on the influx of it in the Florida Current, it could increase this month along North Florida beaches, however, this is unlikely since a prolonged southeast wind direction is not expected over the next couple of weeks which would keep it offshore.

Locally it arrives in abundance when the Bermuda ridge shifts northward or a tropical storm moves through. Winds would need to stay in a southeast direction for several days to force the Sargassum from the Gulf Stream which flows northward about 90 miles offshore.

Historically July is the peak month for the seaweed by oceanographers at USF say more Sargassum may enter the Caribbean Sea and the Gulf of Mexico in the following months following major ocean currents.

About the Author:

After covering the weather from every corner of Florida and doing marine research in the Gulf, Mark Collins settled in Jacksonville to forecast weather for The First Coast.