Condiciones del plancton en una estación fija: Puerto El Morro-Playas, Golfo de Guayaquil, 2000-2002
Bonilla Coello, M.A.
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En este estudio se examina la abundancia estructura poblacional y variación temporal del plancton, especialmente de copépodos en el Golfo de Guayaquil, a través de tres años de estudio, en condición no El Niño.Changes on some oceanographic conditions as well surface planktonic community structure were studied during 33 months (December 1999- August 2002) at a fixed station in the Gulf of Guayaquil. Copepods, ostacods and decapod larvae were the most abundant zooplankton (300 µ mesh size) taxa, followed by fish larvae, chaetognaths, medusae, and mysidaceans. The lower abundance taxa were fish eggs, polychaeths, amphipods, pteropods, lamellibranch, cirriped larvae, and gasteropods. Phytoplankton was dominated by diatoms. The effect of the oceanographic variability on the zooplanktonic distribution, abundance, and population dynamics is unknown due to lack of appropriate continuity on sampling and analyses. The two most abundant copepod species were identified. Acartia danae dominated on the dry season, and Labidocera lubbocckii on the rainy season. Although, in general, copepod abundance was high, this diminished during the rainy seasons of 2000 (138-199 org/m3) and 2002 (175-327 org./m3), with relation to 2001 (1235-2238 org/m3). In march and april it was (6785 y 19887 org./m3). Ostracods, mainly Conchoecia sp., were relatively abundant (compared to copepods) and they were sometimes present in higher numbers. Decapods larvae were more abundand during the rainy season, specially in 2002. High abundance of copepods was find to be associated to lower water temperature, and decapod larvae, to higher temperatures. Diatoms were the main components of the phytoplankton community, with dominance of Skeletonema costatum, Coscinodiscus excentricus y Thalassiotrix frauenfeldii.