What is sargassum, the seaweed that washes up on Florida beaches?

The Florida Department of Health says sargassum occurs naturally and is abundant in the Atlantic Ocean and the Gulf. It is common in the Sargasso Sea, a part of the North Atlantic that is surrounded by four currents but no land. At sea it is habitat for crabs, shrimp, sea turtles and fish such as tuna and marlin.

On the beach, it causes problems as it rots. Decaying sargassum gives off hydrogen sulfide, a gas that smells like rotten eggs. The Health Department says the gas can irritate the eyes, nose and throat, and people with asthma or other breathing problems may be more sensitive to it. In the open air of a beach, the department does not expect health effects for the general public, because the moving air dilutes the gas.

The seaweed itself does not sting or cause rashes, but tiny creatures living in it, such as jellyfish larvae, can irritate the skin. The department's advice: watch children at the beach, avoid touching the seaweed or swimming near it, wear gloves if you must handle it, close windows and doors if you live near the beach, and do not cook with it, because it may contain heavy metals such as arsenic and cadmium. People with asthma or other breathing problems are advised to avoid or limit their time on the beach.

For questions about sargassum, the Florida Department of Health's Public Health Toxicology program, part of its Bureau of Environmental Health in Tallahassee, takes calls toll-free at 877-798-2772.

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