Los grupos del zooplancton de colecciones obtenidas con red CalVET en agosto de 1985 frente a la costa occidental de Baja California Sur, México

Abstract

Plankton groups obtained using vertical tows with a CalVET net at depths of 20 to100 m were analyzed. The collections were obtained in August 1985 off the west coast of Baja California Sur. The objective was to determine the value of this net in the zooplankton studies CICIMAR is conducting in the Eastem Pacific, off Marica. The CalVET net is different in size, speed, duration, angle, and depth of tow from the Bongo net, which is commonly used in plankton studies of de California current. The samples included 37,200 to 1,457,500 organisms/1,000 m3. In these samples, Copepoda make up 67%, the Euphausiacea, Apendicularia, Chaetognatha, Siphonophora, Pteropoda, and Thaliacea amount to 31%, and 12 other plankton groups were only 2%. In these samples, there was a large number of small copepod species and early life stages of euphausiid species. The analysis of the catches shows that the density of these zooplankton groups increases to the north and close to the coast, with the highest densities just south and north of Bahia Magdalena. It was found that samples taken at night were a little larger than those obtained during the day except for Apendicularia, Medusae, and Amphipoda. It was also noted that shallower tows had catch densities nearly 3 times as great as those made at 100 m.