Zooplankton composition and distribution off the coast of Galicia, Spain

Abstract

During June and September 1984, zooplankton samples were collected with other
\nhydrographic and biological data along the Galician coast (NW of Spain). In June copepods
\ncontributed -60% to the total zooplankton community, with larvaceans, siphonophores and
\ncladocerans also abundant. In September >90% of the zooplankton sampled were copepods. The
\ndominant species of copepods in both June and September were Acartia e/ausi, Paracalanus parvus
\nand Temora longicornis. The meroplankton was dominated by echinoderms, bryozoans, barnacle
\nlarvae and bivalve larvae. In June the average zooplankton biomass was 31.08 mg e m-3; the
\nSeptember average was 41.69 mg e m-3 The relationship between the slopes of the regression
\nequations (biomass versus abundance) suggests that the zooplankton assemblage in June was
\ncomposed by larger animals than in September. The major concentration of zooplankton was
\nbetween O and SO m, with both June and September daytime surface samples having 6-7 times the
\namount of organisms than the lower water column (50-100 m). There were no distinct differences in
\ntotal zooplankton abundances at the inshore and offshore stations; however, the inshore stations
\noften had a higher percentage of meroplankton than the offshore stations. In June zooplankton
\nabundance at the northern transects and the western transects was similar. In September there were
\ngreater concentrations of zooplankton in the western Galician shelf as compared with the northern
\nshelf. These differences in the horizontal distribution of the zooplankton were related to upwelling
\nevents.