You’ve been planning your dream beach vacation for months, only to arrive and find the shoreline covered in large piles of smelly, brown seaweed, with even more floating offshore. It’s disappointing, for sure – and increasingly common.

Since 2011, summer scenes like this have played out on beaches in South Florida and throughout the Caribbean.

The consequences are even greater for people who live and work along the Caribbean and Gulf coasts and the coasts of the tropical Atlantic. Large masses of sargassum seaweed can clog harbors, interfering with fishing and boating, and in some cases harm marine life. As the seaweed begins to decompose it releases gases, including hydrogen sulfide, ammonia and methane, raising concerns for both public health and the environment.

To reduce the impact of these sargassum blooms, a crucial first step is understanding why the seaweed started growing in the first place and what’s sustaining it now.

We study the oceans, marine life, and algae blooms, such as sargassum. Our research suggests that these vast mats of smelly seaweed may have entered a self-sustaining cycle, effectively feeding their own expansion. It’s creating a chronic disaster for the affected coasts, with little sign of ending.

Columbus and the great Sargasso Sea

Pelagic sargassum is a type of brown seaweed that floats on the ocean surface and is naturally abundant in the Sargasso Sea, a region of the subtropical North Atlantic.

The seaweed takes its name from sargaço, the Portuguese word for grape. When Portuguese navigators reached the region, they noticed........

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