THE DISTRIBUTION OF ACOUSTIC BACKSCATTER FROM ZOOPLANKTON COMPARED WITH PHYSICAL STRUCTURE, PHYTOPLANKTON AND RADIANCE DURING THE SPRING BLOOM IN THE BELLINGSHAUSEN SEA

The distribution of zooplankton as indicated by acoustic backscatter was compared with that of the phytoplankton biomass, with the degree of the shading caused by the presence of the bloom, with the density structure of the top 250 m of the water column and the current flow in the Bellingshausen Sea in the Austral spring 1992. High concentrations of phytoplankton were observed in an area between 67-68.5 degrees S and 83-88 degrees W. The relative importance of these parameters to the distribution of the zooplankton was observed to vary at different depths between 0 and 300 m. Near the surface and below the pycnocline the light field and the phytoplankton concentrations were more important, but in the intermediate region of the greatest vertical density differences sigma0 was the most important parameter. The spatial spectra of the zooplankton abundance at different depths in the water column were compared.