Surface zooplankton distribution patterns during austral summer in the Indian sector of the Southern Ocean, south of Australia

Abstract

We investigated the composition, distribution and abundance of micro- and mesozooplankton in the Southern Ocean, south of Australia during the austral summer (December–February) of the 2007/08 season using a Continuous Plankton Recorder (CPR). Four CPR tows were conducted during two separate oceanographic voyages under the CEAMARC (Collaborative East Antarctic Marine Census) project. High zooplankton abundance was recorded on each transect in the Polar Frontal Zone (PFZ) and the Inter Polar Frontal Zone (IPFZ). The community structure in these zones was dominated by common taxa including the ubiquitous small calanoid copepods, Oithona similis and Calanus simillimus, accounting for >70% of the total abundance, and copepod nauplii, foraminiferans and appendicularians of the genus Fritillaria spp. also occurred along most of the survey transects. Total zooplankton abundance was comparatively consistent along the four transects, and ranged between 119.8 and 144.7 ind m −3. The results of cluster and IndVal analyses revealed that the dominant species/taxa show similar associations, abundance and distribution patterns on all four transects. There was no evidence of a change of surface zooplankton abundance at the time of towing in this study. Detecting the various distribution patterns of micro- and mesozooplankton species/taxa, and the accumulation of high quality data collected by a consistent methodology will contribute to determining the consequences of climate change impacts on the ecosystem.