Summary
>The Southern Ocean is characterised by the unique Antarctic Circumpolar Current (ACC) which flows eastward uninterrupted around the Antarctic continent. In theory then, the species composition of zooplankton would be expected to be the same in any part of the current, subject to seasonal variation. The Australian Antarctic Division has been conducting surveys of zooplankton composition across the Southern Ocean using continuous plankton recorders (CPR). These surveys cover a wide area between 60 and 160° E and south of 48° S and are conducted throughout the year. Any variation in composition or abundance patterns can therefore be a result of temporal and/or geographical variation. A new joint Japan-Australia CPR program commenced in the 1999/2000 season (JARE 41) with a CPR on the Japanese icebreaker Shirase, using the transects to and from Syowa station, 110°E and 150°E, as fixed time and space transects. These will help interpret the Australian CPR data and serve as a temporal reference to detect interannual variation. In the same season, a CPR was placed on Kaiyo Maru operating south of Africa. This provided us with the unique opportunity to conduct almost simultaneous tows of CPRs along three widely spaced north-south transects in the Southern Ocean to determine the commonality of species composition and patterns across the various frontal zones of the ACC. Kaiyo Maru commenced sampling on 24 November 1999 on transect 25° 30E and covered approximately 495 nautical miles. The Aurora Australis conducted a 430 nmile CPR tow south of Macquarie Island 158° E starting 1 December 1999, followed by Shirase on 8 December 1999 completing 550 nmiles down 110° E. All three tows were analysed at the same time in May 2000 at a specially convened workshop at NIPR, and the results compared with environmental data collected at the same time on each ship. Different distribution patterns of abundance were found between the three transects in relation to the