Biomasa y abundancia de Copepoda (Crustacea) en aguas superficiales del océano Pacífico colombiano durante septiembre de 2007

Abstract

Twenty-three mesozooplankton samples were taken by oblique tows through the ~160 m with a bongo net during September 2007 in the Colombian Pacific Ocean (OPC). The spatio-temporal variation and oceanographic conditions effects on the abundance and volumetric biomass variation of 5 size classes of copepods were evaluated. Temperature, salinity, dissolved oxygen and chlorophyll-a, per station, and their possible relation to the biomass and abundance of those organisms were analyzed. The water column was characterized by a mixed layer of ca., 30 m, a thermocline around 80 m and a bottom layer of cold water (17.4 ± 0.5°C) and low oxygen concentration (1.36 ± 0.2 mg L-1). This stratification may have favored the retention of small-size copepods in the mixed layer. Furthermore, the presence of large size copepods in surface waters could be due to migratory behavior in the water column. The abundance reached 14,933 ind. 100 m-3 (1,641 mm3 100 m-3), where 79% was composed of copepods with cephalothorax length < 1 mm. Their homogeneous distribution could be linked to the physico-chemical conditions of the surface layer in all the study areas. There was a strong correlation among the higher abundances and biomasses with waters with higher density and low concentration of chlorophyll-a.