Abstract

Pelagic Sargassum first appeared in massive quantities in the North Tropical Atlantic during spring of 2011. Not only did it appear in the Lesser Antilles where it was uncommon, but simultaneously appeared off NE Brazil, where it had never before been observed, and along West Africa from Sierra Leone to Benin in the Gulf of Guinea where it was rarely seen. Results from both model tracking and drifting buoys suggested that a consolidation/growth region occurs off West Africa extending into the Gulf of Guinea, with a second such region off NE Brazil associated with the North Brazil Current Retroflection (NBCR). The two regions are connected by the South Equatorial Current (SEC) and the North Equatorial Counter Current (NECC) forming the North Equatorial Recirculation Region (NERR). In the present study, we describe efforts at using current fields from archived model runs and drifting buoys together with Satellite images to predict arrivals in the Lesser Antilles in the spring and early summer of 2016. The basic transport pattern in the NERR associated with a regional bloom hypothesis seems well supported and fundamental to prediction of arrivals on both sides of the North Tropical Atlantic. During May 2016, Sargassum was first spotted off NE Brazil in the area normally dominated by the NBCR. Forward tracking using archived currents successfully indicated that it would arrive in the Lesser Antilles in late July. Cloud cover and high variability in historical current patterns create uncertainties.

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