Estructura comunitaria del fitoplancton de la cuenca Pacífica colombiana durante la campaña oceanográfica Pacífico XXXIX-ERFEN XXXVII

Abstract

Biomass, diversity, composition and taxonomic structure of phytoplankton in the Pacific Ocean of Colombia were studied during Pacific XXXIX-ERFEN XXXVII oceanographic survey. The operative plan of sampling was structured along 40 stations in the Pacific Ocean of Colombia. Discrete sampling of phytoplankton was carried out by oblique trawling with standard phytoplankton net (60μm) in the 25 biological stations. Furthermore, chlorophyll-a concentration at standard depth in each biological stations were estimated by spectrophotometry technique. 126 morph species of phytoplankton, belong to 37 genera, were identified. The Diatom’s genera: Chaetoceros, Coscinodiscus, Thalassionema, Bacteriastrum, Rhizosolenia, Ditylum, Skeletonema, Nitzschia and Pseudonitzschia, were the dominant, following by Dynoflagelate´s genera: Ceratium, Ornithocercus, Pyrophacus, Protoperidinium, Dinophysis, Ceratocorys, Gonyaulax, Podolampas and Amphisolenia. This last taxonomic group trend to increase their abundance in the oceanic zone. Chlorophyll-a concentration was homogenous in the study area, ranged between 11.37 mgm-2 to 38.05 mgm-2 (integrate from 50 to 0m). Moreover, two centers of high Chlo-a concentration were identified: one in the northern sector of oceanic zone (station 75) and the other one in the northern sector of coastal zone (Station 12). Diversity index of Shannon (H’) and richness of Hill’s numbers (N0 y N1) were higher in costal zone that oceanic zone.