The overgrown seaweed is known as the “Great Atlantic Sargassum Belt.” The area extends from the west coast of Africa to the coast of Mexico. The seaweed retains CO2 and is rich in nutrients.
So it could be part of the solution to climate change and the increasing need for food. But too much of a good thing is not good: sargassum seaweed is increasingly a problem in the Atlantic Ocean that threatens people and nature.
Consequences for marine life
“The consequences are major,” says Linda Amaral-Zettler, research leader at the Royal Netherlands Institute for Sea Research (NIOZ). “The proliferating seaweed has enormous consequences for tourism, human health and the ecosystem, for example.”
The floating species of sargassum in the Caribbean washes up on beaches. It dies and starts to rot. This acidifies the coastal waters, causing oxygen levels to drop. This leads to suffocation of coral, seagrass and the fish. It also blocks the light necessary for coastal marine life.
Due to the enormous amount of dead seaweed on beaches, the newly hatched sea turtles cannot reach the sea.
Rat the owner
The tropical tourist beaches smell like rotten eggs because of the washed up seaweed. This is due to hydrogen sulfide, which is released by the rotting process of the huge sargassum carcasses. The stench makes the beaches unattractive to tourists. By inhaling the smell, local residents get health problems, such as headaches, eye irritation and sometimes unconsciousness.
According to Amaral-Zettler, the ‘Dutch’ kingdom islands in the Caribbean are also affected by the sargassum. More sargassum has washed ashore than ever on the Caribbean island of Barbados, which depends on tourism. The seaweed covers the beach for miles. The stench is unbearable, says this resident of the island:
Cause
Scientists suspect that deforestation and intensive agriculture in West Africa and South America are the causes of the enormous growth of sargassum in the Atlantic Ocean. These cause an increase in nutrients that end up in the ocean via the rivers. Nutrients are essential for the growth of sargassum.
In the Netherlands, sargassum does not cause problems. Seaweed that feels at home in the North Sea does spread here, but it occurs almost exclusively on the bottom, less often on the surface.
