Trophic structure of planktonic communities of the southern part of the Pacific Ocean during the spring-summer period

The trophic structure of planktonic communities in the Subtropical Frontal Zone (STFZ) and the northern part of the Subantarctic Zone (SAZ) was studied. Mesoplankton was collected in the southwestern (SWPO) and southeastern (SEPO) parts of the Pacific Ocean. The observations were carried out from November 1986-January 1987 and in December 1989. Carnivores were the dominating group in both regions of STFZ. In the Suhantarctic, coarse filtrators dominated in SWPO and fine filtrators-nanophages in SEPO. The changes in the trophic structure during seasonal succession were traced in SWPO. During succession, the biomass of coarse filtrators decreased and the biomass of euryphages increased. The seasonal development of the community in SAZ was delayed compared with STFZ. As usual, the indices of trophic diversity in SAZ were significantly lower than in STFZ.