High-resolution survey indicates high heterogeneity in copepod distribution in the hydrologically active Drake Passage

A mesoscale grid survey of the epipelagic mesozooplankton of Drake Passage during Antarctic spring, 2008, is evaluated. The station grid comprised six parallel frontal transects between 57 degrees and 60 degrees S in the vicinity of the Polar Front, the distance between transects being 18 km. Several parameters were analysed: total zooplankton biomass, biomass of dominant species and the contribution made by each species to the overall plankton biomass. Mesoscale variability was found in all studied parameters and was comparable in magnitude to the macroscale variability of the same parameters. Because of the high variability in zooplankton distribution in the vicinity of active fronts, hydrobiological studies provide more meaningful results if they are made on the basis of a mesoscale grid survey, not on the basis of a single transect.