A belt of seaweed originating along the west coast of Africa that has been recurring for the past several summers recently extended 5,500 miles into the Gulf of Mexico, posing a risk to some marine animals. This type of algae bloom may become the new normal, according to a report published in Science.
The bloom is called the “great Atlantic Sargassum belt,” named after the sargassum seaweed common in the Sargasso Sea, located in the northern Atlantic Ocean. The seaweed provides an important habitat for fish, bird, turtles and crustaceans, but can be dangerous for other animals.
"In open waters, it's a good thing," says Mengqiu Wang, study lead author, in an interview with Popular Science. "But when it washes onto the coast, it becomes a coastal nuisance."
When they rot, the algae releases hydrogen sulfide, which can irritate the lungs, especially for people with asthma. Microbial decomposers use up oxygen when breaking down the algae, suffocating some marine animals.
Wang started the study to understand why sargassum was washing up in the Caribbean, far from its known African origins. Researchers analyzed factors related to the growth of algae, including sea surface temperatures and nutrient levels.
They concluded that more nutrient-rich water, especially coming from Brazil, was responsible for increased growth. Deforestation in the Amazon is connected to nutrients leaking into the water and as the practice continues to grow, so will sargassum.