Community Ecology Of Meso-and Macro-zooplankton In Prydz Bay, Antarctica

During Chinese National Antarctic Research Expedition (CHINARE) XIII (96/97) and XV (98/99), community structure and geographic distribution of zooplankton in Prydz Bay were studied. All the stations in each investigation were divided into three different types of communities with mathematical methods of cluster-analysis and multi-dimension scaling according to the kinds and abundance of species included in each station. Between 62 and 650S lies Salpa community, with small copepod species Oithona similis and Paracalanus spp encountered in maximum density, and the biggest copepod species Rhincalanus gigas also appeared characteristically, while its nauplii were only found near 620S in large amount. The second community named main oceanic community lies between 65~67oS, which may be controlled by krill and copepods alternatively. Calanoides acutus and Metridia gerlachei inclined to attain maximum density in this community, which was also abundant with Polycheata and Cheatognath. The neritic community locates south of 670S, characterized by Euphausia crystallorophias, in this region laval E up ha us lids were also found in different stages in high density, nauplii 51 6000ind.m2 and calyptopis 6400ind.nf2. Indicator species differentiating the Salpa and the main oceanic community are Salpa thompsoni, Rhincalanus gigas and Cheatognath. Those differentiating the Salpa and the neritic community are Rhincalanus gigas, Metridia gerlachei and calyptopis of Euphausiids. Between the main oceanic and the neritic community, indicator specie mainly is Euphausia crystallorophias, while it抯 not so evident as it for nauplii of Euphaus lids and Onceae spp. The dominant copepod species were incubated on board for egg- production estimation during CHINARE-XV, 13.3 and 5 eggs per female on average were got for Calano ides acutus and Metridia gerlachei respectively. Population structure of Calanoiodes acutus was obviously bimodal, with early stages (CI and CII) and adult more abundant than others. CIs were first found under ice on 5 December, from which we postulate the reproduction begins late October. The new generation of Rhincalanus gigas appeared in January near 62~S in nauplii, and no forms of copepodites were found. So their reproduction must take place aggregately and apparently later than Calanoides acutus.