Distribución del fitoplancton en la región costera del mar ecuatoriano, durante diciembre 2000
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La presente investigación describe el comportamiento del primer nivel trófico (clorofila, feopigmentos, biomasa celular e indicadores del fitoplancton) en el ecosistema costero del mar ecuatoriano, conocer la incidencia de las principales especies que se encuentran formando núcleos de mayor productividad e inter-relacionadas con las condiciones ambientales durante el Crucero realizado en diciembre/2000.This study was carried out during December 2000, onboard the R/V Orion of the Oceanographic Institute of the Ecuadorian Navy. The objetive was to establish the relationship between chlorophyll "a" content and the abundance of species or groups of species of micro-algae inside a region with ocean-climate system variability in the Tropical Pacific Ocean along the Ecuadorian coast. The highest chlorophyll content was found between 1°3 S and 3°S, with a positive correlation to the cellular biomass, including species of phytoplankton such as Rhizosolenia stoltherfothi, Thalassiosira subtiles, Pseudonitzschia delicatissima, P. longissima, Leptocylindrus danicus, Gymnodinium sp., y Messodinium rubrum. However, the biomass calculated from the content of the 55 µm mesh size was dominated by Rhizosolenia imbricata, T. subtiles, Chaetoceros affinis, L. danicus, Chaetoceros curvisetus. The dinoflagellates showed concentrations of species that characterized zones of warm water masses (Protoperidinium crassipes, Gonyaulax polyedra, Dinophysis caudata towards the NE, and C. tripos, G. polyedricum, C. furca towards the SE of the study area). The phytoplankton distribution did not reflect the position of the Equatorial Front, determined as an almost zonal phenomenon with a weak surface thermal gradient (23-25°C). The high abundances of M. rubrum and Gymnodinium sp., might have been related to the influence of the cold Humboldt Current and this may have produced some "red tide" events towards the coastal margin.