Nella Dan: AAMBER Cruise Chlorophyll a Data

The composition, size and abundance of phytoplankton and microzooplankton were measured across a transect from Prydz Bay to Australia during late March 1987. Phytoplankton populations were low, with concentrations of chlorophyll a ranging from 0.08 to 0.22 mg.m-3. Small cells predominated numerically; nanoplankton consistently represented 55 to 68% of the total cell number while picoplankton represented 27 to 44%. Microplankton never represented more than 3% of cells by number, but constituted 57 to 93% of the total cell volume, and accounted for most of the latitudinal variation in total volume. Small flagellates, not identifiable by light microscopy, were the most numerous cells encountered across the transect, with a five-fold increase in abundance at 47S. Numbers of diatoms (most less than 20 microns in size) increased markedly south of the Antarctic Convergence, with a strong correlation to the concentration of silica. Dinoflagellate numbers were relatively constant across the transect, although somewhat higher north of 50S. Those less than 20 microns in size were most numerous and accounted for most of the numerical variation. HPLC analysis of chlorophyll and carotenoid pigments showed a peak of peridinin which coincided with the flagellate peak at 47S, but not with observed dinoflagellates, suggesting that the flagellate peak included unrecognized dinoflagellates. Chlorophyll b and prasinoxanthin were also associated, suggesting a significant contribution by prasinophytes. Almost no cyanobacteria were observed south of the convergence, although very large numbers, which correlated with the abundance of zeaxanthin, were encountered to the north. Numbers of ciliates and tintinnids were quite variable although they followed each other closely. Numbers of both were low in the region of the Antarctic Convergence.

1987年3月下旬，研究团队沿普里兹湾（Prydz Bay）至澳大利亚的海洋断面开展调查，测定了浮游植物（phytoplankton）与微型浮游动物（microzooplankton）的群落组成、细胞丰度及生物量规模。调查区域内浮游植物种群丰度较低，叶绿素a（chlorophyll a）浓度介于0.08~0.22 mg·m⁻³之间。小型细胞在总细胞数量上占据主导：超微型浮游植物（picoplankton）占总细胞数的27%~44%，微型浮游植物（nanoplankton）则稳定占比55%~68%；而小型浮游植物（microplankton）的细胞数量占比从未超过3%，但其细胞总体积占比可达57%~93%，总细胞体积的纬度变化主要由其贡献。光学显微镜（light microscopy）无法识别的小型鞭毛藻是断面中数量最多的类群，在南纬47°处其丰度提升了5倍。硅藻（diatoms，多数个体粒径小于20μm）的丰度在南极辐合带（Antarctic Convergence）以南显著升高，且与硅浓度呈强相关性。甲藻（dinoflagellates）的丰度在整个断面相对稳定，仅在南纬50°以北区域略高；其中粒径小于20μm的个体数量最多，主导了甲藻群落的数量波动。对叶绿素与类胡萝卜素的高效液相色谱（HPLC）分析显示，甲藻素（peridinin）的浓度峰值出现在南纬47°处，与小型鞭毛藻的丰度峰值重合，但与观测到的甲藻种群并不匹配，这表明该鞭毛藻峰值中包含未被识别的甲藻类群。此外，叶绿素b（chlorophyll b）与绿藻黄素（prasinoxanthin）的分布具有显著相关性，提示绿藻门（prasinophytes）在群落中做出了显著贡献。南极辐合带以南几乎未观测到蓝细菌（cyanobacteria），而在辐合带以北区域则出现了大量蓝细菌，其丰度与玉米黄质（zeaxanthin）的含量呈显著正相关。纤毛虫（ciliates）与砂壳纤毛虫（tintinnids）的丰度波动较大，但二者的丰度变化趋势高度同步；两类群在南极辐合带区域的丰度均较低。