Procesos planctónicos en el Golfo de Guayaquil (Campo Amistad) julio-agosto/2001

Abstract

El presente trabajo es una contribución al estudio del fitoplancton y zooplancton marino-estuarino y su relación con las condiciones ambientales físico-químicas presentes en el entorno de la plataforma Amistad de producción de gas (Campo Amistad - Golfo de Guayaquil Externo), realizada por el Instituto Oceanográfico de la Armada en el B/I ORION durante julio-agosto del 2001.

This research is part of an environmental monitoring of plankton and its physical and chemical response around the platform located offshore Campo Amistad, near Santa Clara Island, southeast of the Gulf in external Guayaquil. The study was carried out between july 30 and august 31-2001, onboard the R/V Orión of te Oceanographic Institute of the Ecuadorian Navy. The chlorophyll "a" biomass presented values between 0.6 and 1.52 mg/m³ in surface waters, with averages of 1.07 to 0.99 mg/m³ (10 m), 0.79 (20 m) and 0.58 (30 m) mg/m³. The larger amounts of biomass and daily variability were found in the northern part of the platform, while the opposite trend was observed in its western area. One hundred and three phytoplankton species were identified, with dominance of centric diatoms of mainly Skeletonema costatum and Chaetoceros curvisetus. Dinoflagellates presented high diversity and low biomass; Ceratium dens was the dominant species, characterizing influences of external water masses in the estuary. The zooplankton fauna was represented by 28 groups, with dominance of cladocera and copepods; the highest density of organisms was found the 17h00 hours. High density of cladocera presented a strong positive relationship to phytoplankton abundance, and a negative correlation to copepod abundance. The environmental conditions in the surface thermal structure were almost stable, with an average of 22.5°C. The lowest temperatures were found southwest of the platform (subsurface), coincident with a slight increase in nutrients (nitrate and silicate). The marine biota associated with these environmental conditions presented high diversity, implying the absence of eutrophication incidence in the estuary area of the platform.