Spatial distribution of micro- and meso-zooplankton in the seasonal ice zone of east Antarctica during 1983-1995

Historically, most studies about the geographic distribution of zooplankton in the Southern Ocean have been focused on the macro-sized zooplankton (2-20 mm), such as the Antarctic krill and larger-sized copepods. On the other hand, despite the high abundance and biomass, the distribution patterns of micro- (20-200 μm) and meso-sized (200 μm-2 mm) zooplankton communities are little understood. In this study, we investigated the distribution patterns of larger micro-zooplankton (100-200 μm) and meso-zooplankton communities in the seasonal ice zone in the Cosmonaut Sea near Syowa Station and examined the effects of environmental factors and water properties on these communities. The investigation was based on samples collected with 100 μm mesh nets, which are appropriate to estimate the quantitative abundance and community structure of micro- and meso-zooplankton species between 1983 and 1995. Cluster analysis of the samples revealed that the distribution of macro-zooplankton species was influenced by the temperature and salinity of ocean fronts. Among the meso-zooplankton, cyclopoid and small calanoid copepods tended to be ubiquitously distributed. However, among the micro-zooplankton, the distributions of foraminiferans and tintinnids were associated with sea ice extent. The distribution of micro- and meso-zooplankton communities could be used to estimate the impact of environmental changes on the marine ecosystem in the Southern Ocean.