Understanding how floating sargassum seaweed travels in the ocean
By measuring how wind and currents act on sargassum patches, a new study co-authored by AIAS fellow Christian M. Appendini sheds light on how floating sargassum travels in the ocean. These findings can improve forecasting tools and contribute to better preparedness for coastal sargassum flooding events.
Massive arrivals of the seaweed sargassum are an increasing problem on the coasts of the Gulf of Mexico. Scientists and stakeholders need better ways to predict their arrival in order to improve marine management and control strategies.
To better understand the forces driving the transport of sargussum to the coast, an international group of researchers with AIAS-AUFF Fellow Christian Appendini on board measured drag on sargassum patches induced by airflow and water current in controlled laboratory experiments. The team of researchers used both live and plastic surrogate patches to mimic the size and buoyancy of the sargassum.
Improving measurement tools
The results of the experiments are published in the Journal of Geophysical Research: Oceans and contribute with novel insights on the physics of saragassum. More specifically, the study shows that the drag coefficient based on water current was nearly constant, while the drag coefficient based on airflow decreased. As the flow speed of the sargassum increased, streamwise elongation of sargassum patches was observed, while their frontal area remained unchanged.
Considering this flow-induced deformation of the sargassum, the researchers proposed a correction factor for more accurate estimates of drag. Their results will contribute to improve estimates of forces on floating patches of sargassum, and hereby allow for better large-scale predictions of their transport and arrival in coastal areas.
“The study shows that the shape of sagassum changes under flow and that this strongly affects their transport. These findings are important for improving forecasting tools and will contribute to better preparedness for coastal sargassum flooding events,” edxplains Christian Appendini, AIAS-AUFF Fellow and co-author of the study.
The full scientific paper behind the study
‘Quantifying Drag on Floating Sargassum Patches Under Combined Air and Water Forcing’ in: Journal of Geophysical Research: Oceans by Yihui Wang et al, 15 March 2026: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2025JC023529
Contact
Christian Appendini, AIAS-AUFF Fellow & Professor at UNAM, Engineering Institute, Mexico
E-mail: cma@aias.au.dk
Aarhus Institute of Advanced Studies, AIAS
Høegh-Guldbergs Gade 6B
DK-8000 Aarhus C
Denmark