World's largest seaweed bloom stretches from Africa to the Gulf of Mexico

TAMPA, Fla. (FOX 13) - University of South Florida researchers recently released a study on “brown macro algae” or sargassum, the world’s largest brown algae bloom called the "Great Atlantic Sargassum Belt."

“It can grow so large that it blankets the entire surface of the tropical Atlantic Ocean to the west coast of Africa to the Gulf of Mexico,” said FOX 13’s Dave Osterberg explained during a Good Day segment.

In 2018, there were more than 20 million tons of sargassum floating on the surface of the Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico. 

In the spring and summer, the sargassum belt is formed by discharge from the Amazon River due to increased deforestation and fertilizer use. In the winter, upwelling off the West African coast brings nutrients from deep waters to the surface, where sargassum thrives. 

As sargassum is created, some is also dying, creating a pattern of both processes. Sargassum takes its shape based on ocean currents and connects by ocean circulation.

"Based on the last 20 years of data, I can say that the belt is very likely to be a new normal,” said Dr. Chuanmin Hu of the USF College of Marine Science.

While in patches of open ocean, sargassum can provide a habitat for some species, like turtles, fish, crabs and birds. The problem occurs is when the sargassum builds and becomes too thick. It makes it hard for these species to move and breathe, killing the animal off. 

When the sargassum dies, it sinks, smothering other sea grasses and corals on the bottom of the ocean. 

“Not to mention when this stuff reaches the beach, it releases hydrogen sulfide gas and smells like rotten eggs,” added Osterberg. 

It also is affecting tourism in some countries. In 2018, Barbados had to declare a national emergency when the algae took over the island.

“We are dumping into the oceans and obviously you are starting to see the result now,” said Osterberg.

LINK: Learn more about USF's study by clicking here.