(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（R/V Akademik Mstislav Keldysh）第50次科考航次期间，研究团队于失落城（Atlantis underwater massif）与断脊热液田上方开展3次和平号载人潜水器（Mir manned submersibles）下潜作业，同步完成浮游生物计数，并使用BR网（BR net）实施2次垂直浮游生物拖网采样。 在亚特兰蒂斯海山（Atlantis seamount）上方，未观测到浮游生物浓度出现显著升高。 在失落城热液田上方，研究证实近底层水体与上覆水层内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（euphausiids）与端足类（amphipods）近底层集群现象，似乎是受潜水器探照灯吸引所致，而非自然形成的种群聚集。