
© Lauren Dauphin and Joshua Stevens/ModisA record seaweed bloom has been recorded in the Atlantic ocean in 2023
Nearly every spring and summer since 2011, a giant bloom of seaweed has developed in the central Atlantic Ocean. Patches of floating brown seaweed — known as
Sargassum — have stretched from the west coast of Africa to the Gulf of Mexico in what is known as the "
Great Atlantic Sargassum Belt." In March 2023, scientists found that the amount of
Sargassum floating in the belt was the largest of any March on record.
The map above shows
Sargassum density in the central Atlantic Ocean (including the Caribbean Sea and Gulf of Mexico) for March 2023. Red and orange areas show where
Sargassum densities were the highest, in terms of the percent of the pixel covered with the seaweed. The data for the map were developed by scientists at the University of South Florida (USF) College of Marine Science using data from the
Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on NASA's Terra and Aqua satellites.
USF researchers estimate that the
Sargassum belt in March totaled about
13 million tons, a record amount for this time of year. "So far this year, record high
Sargassum abundance is mostly in the central East Atlantic," said Brian Barnes, a marine scientist at the Optical Oceanography Laboratory at USF. "But in other parts of the Atlantic and Caribbean, its abundance is still high — in the 75th percentile of measurements made between 2011 and 2022."
Comment: More on the extraordinary seaweed bloom: