Sargassum Seaweed Information

What is Sargassum?

Sargassum is a naturally occurring seaweed that floats freely on the ocean surface and can be present in the Atlantic Ocean and the Gulf of Mexico. It provides crucial habitat for many marine species, including endangered sea turtles, which, upon hatching on our beaches, make their way out to the sargassum to spend their juvenile years feeding and growing amongst the seaweed mats. It is also an important element in shoreline stability. Sargassum also provides nutrients to the shoreline and can replenish areas that suffer beach erosion due to hurricanes and storms, thereby helping to keep our shorelines resilient.

Where does Sargassum come from?

Sargassum comes from the largest bloom of macroalgae in the world, which makes up the Great Atlantic Sargassum Belt (GASB) and is often present on the surface of the tropical Atlantic Ocean from the west coast of Africa to the Gulf of Mexico.

Where is Sargassum currently located?

The National Oceanic and Atmospheric Administration, in collaboration with the University of South Florida, provides Sargassum reports here:

Does Sargassum cause skin rashes and blisters?
Sargassum does not sting or cause rashes. However, tiny organisms that live in Sargassum (like larvae of jellyfish) may irritate skin if they come in contact with it.

Why does Sargassum smell so bad?

When washed ashore, Sargassum will decompose (rot). Rotting Sargassum causes the production of hydrogen sulfide gas which smells like rotten eggs.

How can hydrogen sulfide affect my health?

Hydrogen sulfide can irritate the eyes, nose, and throat. If you have asthma or other breathing illnesses, you will be more sensitive to hydrogen sulfide. If you are exposed to hydrogen sulfide for a long time in an enclosed space with little air flow (like some work exposures), it can affect your health. However, hydrogen sulfide levels in an area like the beach, where large amounts of air flow can dilute levels, is not expected to harm health.

What is the process of managing seaweed along the beach?

Florida Fish and Wildlife Conservation Commission takes the lead in monitoring efforts of Florida’s coastal waters, while the Florida Department of Environmental Protection coordinates with municipalities throughout Florida to identify the best way they can manage Sargassum that may come inshore or on their beaches, whether that be to integrate it into the beach, haul it for disposal or even compost it.

More information: