In a new study, scientists from NOAA, University of South Florida, Florida International University, University of Miami, and LGL Ecological Associates, compared wind information alongside Sargassum Inundation Risk (SIR) maps against citizen science reports of inundation in the coasts of Florida, Gulf of Mexico, Bahamas, and Caribbean regions. With present SIR maps, inundation is considered as more likely if large densities of satellite-detected Sargassum are near a coast. The scientists in the study found that shoreward wind velocity used in conjunction with SIR indicators greatly improves the agreement with coastal observations of Sargassum beaching compared to SIR indicators alone. Including wind metrics in SIR maps will allow for improved understanding of Sargassum trajectories in coastal areas for forecast purposes.
When massive mounds of golden-brown seaweed began piling up on beaches throughout the Caribbean and West Africa in summer of 2011, the question of where it came from probably mattered less to residents and businesses than how they were going to get rid of it. Certainly, few would have connected the Sargassum seaweed invasion to the extremely snowy 2010-11 winter in the eastern United States. But according to a hypothesis proposed by a team of NOAA AOML-led scientists in 2020, the two phenomena share an origin story: an extremely strong and long-lasting shift of the North Atlantic Oscillation into its negative phase back in 2010.
Massive bloom of seaweed in tropical Atlantic raises the risk for Caribbean, Gulf, and Florida beach impacts in coming months
Earlier this year, ocean scientists raised an alert about the large amount of seaweed drifting in the tropical Atlantic this spring. Experts warned that the region’s annual spring bloom of Sargassum—a free-floating brown macroalgae from the North Atlantic that suddenly appeared in large quantities in the tropics in 2011— was the densest observed in March since scientists began tracking the phenomenon with satellite images twenty years ago. Excessive amounts of Sargassum raise the chances that large mats will break free from the prevailing currents and wash ashore later this spring and summer in the Caribbean, Gulf of Mexico, and around Florida.