Massive Flotillas of Putrid Seaweed Wash Up in Caribbean and S. Florida, Threatening Beaches

Beaches from Florida to French Guiana in S. America have been plagued in recent years by massive influxes of Sargassum blooms, threatening not only the ecosystem but also tourism as resorts battle tons of the seaweed-like grass washing up on beaches on a daily basis. This year is gearing up to be one of the worst Sargassum invasions in recent memory.

Sargassum is abundant in the ocean, originating in the Sargasso Sea, a region of the North Atlantic. The seaweed forms floating rafts that can stretch for miles. The leaves and branches contain gas-filled berry-like structures called pneumatocysts that make the plants buoyant and able to float on the surface of the water. The floating masses of Sargassum provide an essential habitat for fish, sea turtles, birds, and hundreds of other sea creatures.

But in recent years Sargassum has been washing up on shores in mass quantities, creating smelly piles on beaches and distressing tourists. The Caribbean has been hardest hit, but the Sargassum has become a nuisance in Florida and off the West Coast of Africa as well. (See map of the affected areas below.) While normally harmless to humans, when it washes up on shore, the seaweed and animals contained within quickly begin to die and decompose, leaving a rotten egg smell in its wake.

Brian LaPointe, a research professor with Florida Atlantic University-Harbor Branch Oceanographic Institute, told the Miami Herald last month, “I think the potential exists that the situation could worsen in parts of Florida.” LaPointe added, “We’ve seen problems in the Florida Keys in the past couple years… It’s gotten to the point in places where people will avoid swimming. It’s not something you’d really want to swim through or in."