Distribución latitudinal del fitoplancton entre Islas Cocos - Galápagos, Noviembre-Diciembre 2001
El propósito de esta investigación fue realizar una evaluación de la distribución de las especies del fitoplancton (red 55u), durante noviembre-diciembre-2001, en una región latitudinal que implica dos áreas insulares del Pacífico Tropical Islas Cocos e Islas Galápagos, estudios que serán de gran contribución científica para el conocimiento de estas especies en la región del mar ecuatoriano.The investigation is a contribution to the study of the geographical distribution of phytoplankton. Water samples were obtained with a 55 µm mesh size net in a transect from Punta Arenas to Cocos Island (Costa Rica) and to the Galapagos Islands (Ecuador), on board R/V Robert Seaman of the Sea Educational Association (Woods Hole), between November 26 and December 10, 2001. The identification of 91 phytoplankton species was possible, including 24 Centricae and 11 Pennatae diatom species, 43 dinoflagellate species and 13 species among others (Tintinnids, Silicoflagellates and Cianophytas). In the northern part of the transect, between 6° and 5° N, the species Pseudonitzschia delicatissima was dominant, this species is associated to the presence of species such as Blefarocysta splendor-maris, Ceratium furca, Goniodoma polyedricum, and Planktoniella sol (5° S), representing strictly warm water conditions. Thermal values were between 27.25 °C and 27.04 °C and salinities of 33.00 UPS were found. The presence of Ornithocercus steinni and Pyrophacus steinni, species of warm and oceanic conditions, possibly inidicate areas of not very defined mixtures in the intermediate part of the studied transect (4° S - 0°) with temperatures ranging between 26.8 °C and 24.6 °C and salinities between 33.23 and 33.42 UPS. The biomass of phytoplankton decreased in the southern region (northwest of Floreana Island, 1°1 S) and very high diversity of species of warm conditions (Ceratium tripos), and the cold condicitions (Chaetoceros and Bacteriastrum) was found; the temperature record showed 21.5 °C and the salinity was 34.86 UPS.