TABLE 1. - Taxa list at Bahi'a Ushuaia and Bahi'a Golondrina

This paper describes the composition and abundance of mesozooplankton of Bahi'a Ushuaia and Bahi'a Golondrina. These small bays are located in the northern Beagle Channel. Sampling was carried out from January 20 to 23, 2001 and samples were collected from the upper layer at nine stations. This study is the first research on mesozooplankton in this part of the Beagle Channel. Due to their dominance in the mesozooplankton community, we compared our Copepoda data with those reported by other authors from Antarctic coastal environments. By applying cluster analysis, we found two station groups in both bays: one in slightly polluted zones and the other in undisturbed external zones. Four assemblages in Bahi'a Ushuaia and two in Bahi'a Golondrina were determined by using non-metric multidimensional scaling (MDS) and cluster analysis. Mesozooplanktonic assemblages showed a certain resemblance in zones with and without anthropogenic influence. Most of the copepod species in our samples are typical of the sub-Antarctic region. Oithona similis (=0. helgolandica sensu Ramirez, 1966), Oncaea curvata, and Ctenocahmus citer show either similar or higher abundances at Antarctic coastal sites, including the upper layer in oceanic areas, in comparison with sub-Antarctic coastal localities. This suggests that, in agreement with other findings, the Polar Front is probably not a major geographic boundary for the distribution of these species.

本论文阐述了乌斯怀亚湾（Bahía Ushuaia）与戈隆德里纳湾（Bahía Golondrina）的中型浮游动物（mesozooplankton）群落组成及丰度特征。这两处小型海湾坐落于比格尔海峡北部。采样工作于2001年1月20日至23日开展，在9个站位的表层水体采集了样本。本研究是针对比格尔海峡该区域中型浮游动物的首次系统性调查。鉴于桡足类（Copepoda）在中型浮游动物群落中占据优势类群地位，本研究将获取的桡足类数据与其他学者报道的南极沿海生境相关数据进行了对比。通过聚类分析，我们在两处海湾中均识别出两个站位集群：一类位于轻度受污染区域，另一类位于未受干扰的外湾区域。结合非度量多维标度法（non-metric multidimensional scaling, MDS）与聚类分析，本研究在乌斯怀亚湾划分出4个群落单元，在戈隆德里纳湾划分出2个群落单元。中型浮游动物群落在受人为干扰与未受干扰的区域中呈现出一定的群落相似性。本研究采集样本中的多数桡足类物种均为亚南极区域的典型物种。相似镖剑水蚤（Oithona similis，即Ramirez于1966年报道的O. helgolandica sensu Ramirez, 1966）、弯曲独眼剑水蚤（Oncaea curvata）与Ctenocahmus citer在南极沿海生境（包括大洋表层水体）中的丰度，与亚南极沿海区域相比要么相似，要么更高。这一结果与其他研究结论一致，表明极锋（Polar Front）可能并非制约这些物种分布的主要地理屏障。