Nuevas aportaciones a la biogeografía de cocolitóforos en el Pacífico ecuatorial y suroriental

Resumen

For this proposal 114 surface sediment samples from the Equatorial and Southwestern Pacific were analysed, recovered during three cruises: Génesis III-RR9702A, NEMO-Me0005A and PUCK: Valparaiso-Talcahuano. A total of 19 different species (or groups in some cases) were identified using petrographic microscope. Five biogeographic coccolithophore zones have been established taking into account the distribution patterns of the taxa and some physical parameters such as temperature and salinity. These zones are: -Tropical North, characterized by an assemblage mainly composed of Gephyrocapsa oceanica, Florisphaera profunda, «small» Gephyrocapsa and Gephyrocapsa muellerae. - Equatorial, basically dominated by placoliths. -Tropical South, where F.profunda, G.oceanica, «small» Gephyrocapsa, Calcidiscus leptoporus, Emiliania huxleyi and G.muellerae are dominant. Characteristic taxa are Umbilicosphaera sp., Calcisosolenia sp., Oolithotus sp., Syracosphaera spp. and Rhabdosphaera clavigera. -Subtropical South, with an assemblage dominated by gephyrocapsids, F.profunda, C.leptoporus and Helicosphaera carteri. -Transitional-Subpolar, where «small» Gephyrocapsa is the most abundant taxa, although E.huxleyi, G.muellerae, C.leptoporus, G.oceanica, F.profunda, C.pelagicus (very abundant in this zone) and H.carteri are also well represented.