Distribution of Microzooplankton across the Frontal Systems of the Southern Ocean

Microzooplankton was analysed between $40^{\circ}s$ to $53^{\circ}s$S and $140^{\circ}E$ to $146^{\circ}E$ of the Sourthern Ocean from November 18 to November 30, 1995 to investigate the influence of frontal systems. The density and carbon biomass of microzooplankton were clearly associated with frontal systems, and at least 4 different communities were identified. The Subtropical Convergence Zone and Antarctic Polar Front Zone were the major biological boundaries recognized in the Southern Ocean. Ciliates predominated other microzooplankton in density and carbon biomass. Non-tintinnid ciliates occupied more than 70% of the total microzooplankton, and Laboea spp. was the major component of the non-tintinnid ciliates. The density and carbon biomass showed a decreasing tendency toward south from $40^{\circ}S$ to the $53^{\circ}S$ transect. The ecological importance of a frontal zone is confirmed by the microzooplanktonic data obtained from this study.