ABSTRACT 1294 | POSTER 124
LONG-TERM SHIFTS AND TRANSPORT DRIVERS OF PELAGIC SARGASSUM IN THE MEXICAN CARIBBEAN
Pelagic Sargassum influxes have intensified across the Caribbean since 2011, but it is still not fully understood how changes in upstream supply and transport shape what eventually reaches the Mexican Caribbean. We developed a homogenized daily satellite time series of Sargassum cover for the Mexican Caribbean and Central Lesser Antilles from 2011 to 2026 using products from the USF Sargassum Watch System and compared it with independent Copernicus NFAI detections. Daily surface currents and winds from the Copernicus Marine Service were used to examine transport pathways and possible losses across the basin. Ten blooms were identified in the Mexican Caribbean between 2014 and 2026, lasting about 2–9 months. Despite strong interannual variability, blooms appear to occur earlier, last longer, and reach greater intensity. The 2024 season was unusually weak, but it was followed by record influxes in 2025 and 2026, with peak cover about four times the median peak of earlier events. Blooms in the Central Lesser Antilles preceded Mexican Caribbean events in seven of ten bloom seasons, usually by one to two months, and upstream bloom magnitude explained most of the year-to-year downstream variability (R² = 0.93). Yet only part of that upstream signal reached Mexico: downstream-to-upstream bloom ratios ranged from 0.14 to 0.63. Satellite and circulation fields illustrate how Sargassum can be diverted, stranded, or lost during transit. Upstream supply therefore sets the potential for major influxes, while transport and losses determine how much ultimately reaches Mexico, providing a basis for improved early warning systems.
Julio Lara Hernandez, University of Victoria, [email protected]
Nelson de Almeida Gouveia, University of Victoria, [email protected]
Santiago Ramirez Said, University of Victoria, [email protected]
Maycira Costa, University of Victoria, [email protected]
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