Temporal Changes in the Composition of Beached Holopelagic Sargassum spp. along the Northwestern Coast of Cuba

Abstract

Since 2011, the distribution, abundance, and composition of holopelagic Sargassum spp. (sargasso) have changed by the emergence of the Great Atlantic Sargasso Belt (GASB) in the northern tropical Atlantic. We expected that the north of the Cuban coast would receive sargasso from both the original Sargasso Sea and the GASB. We systematically monitored six beaches on the NW coast of Cuba to assess changes in sargasso composition from June 2019 to June 2021. During landing months, mean Sargasso wet biomass was at 1.54 kg/m2 (SE: 0.7), which was considerably lower than the sargasso on the Atlantic coasts directly impacted by GASB. Eleven out of 13 landings occurred in the autumn-winter seasons 2019–2020 and 2020–2021, with a dominance of S. natans I (accounting for 41–63% of total biomass), followed by S. fluitans III (25–36%) and S. natans VIII (12–31%). This composition is similar to those observed on the Sargasso Sea. During this season, dominant winds (≥14 km/h) came from northern (N), eastern (E), and east-northeastern (ENE) directions. In May and August 2020 (spring-summer season), S. fluitans III dominated (52–56%), followed by S. natans VIII (33–43%) and S. natans I (5–12%). This composition is similar to those observed on GASB-impacted Atlantic coasts in the spring-summer seasons (April to September). During this season, dominant winds (≥20 km/h) came from eastern (E) and east-northeastern (ENE) directions. Thus, the NW Cuba’s morphotype composition suggests that landings have different origin sources depending on season and specific meteorological and oceanographic conditions.