Felipe de Jesús García-Romero , Juan Carlos Herguera García , Jörg Bollmann , José Rubén Lara Lara, Mara Yadira Cortés-Martinez, Amaru Márquez-Artavia

We present new results of the coccolith fluxes in the Perdido and Coatzacoalcos regions of the Gulf of Mexico and explore the environmental variables that may control them. Two sediment trap moorings located at a water depth of 1100 m collected settling particles from June 2016 to July 2017. Both regions showed similar seasonal distributions in total coccolith fluxes, with the highest recorded fluxes during winter, decreasing through spring, and moderate fluxes in summer and autumn. The Perdido sediment trap shows slightly higher annual average fluxes of 3.09 x 109 ± 0.89 x 109 coccoliths per m-2d-1, in comparison to the Coatzacoalcos trap of 1.88 x 109 ± 1.13 x 109 coccoliths m-2d-1. The Perdido trap collected 47 species of coccoliths, in comparison with the Coatzacoalcos trap with 56 species throughout the study period. The species composition was dominant in both regions by Emiliania huxleyi,Gephyrocapsa oceanica, and Florisphaera profunda, reaching more than 85 %. The Upper Photic Zone (UPZ) species association was dominant throughout the study period, showing higher fluxes during winter, associated with the seasonal deepening of the mixed layer depth. In addition to the controls by the mesoscale forcings by the anticyclonic eddy (Poseidon) in the Perdido region and the semi-permanent cyclonic eddy (Campeche Bay) in Coatzacoalcos. The interaction between these mesoscale eddies with the continental shelf results in the advection of nutrient-rich waters to the deep ocean thereby increasing the coccolith productivity and consequently export-fluxes. Our results of the coccolith fluxes and the processes that modulate them in the Southwest of Mexico help to understand the different controls on the calcareous nannoplankton export in oligotrophic regions close to the continental shelf.