(Table 2) Abundance of the main groups of planktonic animals in the 250-900 m water layer at the Broken Spur and Lost City sites according to visual counts from the Mir manned submersibles in 2002 and 2005

Three dives of the Mir manned submersibles with plankton counts and two vertical plankton hauls with a BR net were carried out above the Lost City (Atlantis underwater massif) and the Broken Spur hydrothermal fields during cruise 50 of R/V Akademik Mstislav Keldysh. Above the Atlantis seamount no significant increase in plankton concentration was found. Above the Lost City field horizontal heterogeneity of plankton distribution in the near-bottom layer and in overlying water layers was shown. Near-bottom aggregations of euphausiids and amphipods previously reported by other scientists seem to be related to attraction of these animals by the submersible's headlights rather than represent a natural phenomenon.

在“姆斯季斯拉夫·凯尔迪什院士”号研究船第50航次期间，研究团队于失落城（亚特兰蒂斯水下海山）与断脊热液田上方，开展3次和平号（Mir）载人潜水器下潜以同步获取浮游生物计数数据，并使用BR拖网完成2次垂直浮游生物拖网采样。在亚特兰蒂斯海山上方，未观测到浮游生物浓度出现显著升高现象。在失落城热液田上方，研究证实近底层水体及上覆水层中的浮游生物分布存在水平异质性。此前其他学者报道的磷虾类与端足类近底层集群现象，似乎是潜水器前大灯吸引这些生物所致，而非自然形成的生物集群现象。