Zooplankton distribution above the Lost City (Atlantis massif) and broken spur hydrothermal fields in the North Atlantic according to the data of visual observations

Three dives of 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 the plankton concentration was found. Above the Lost City field, the horizontal heterogeneity of the plankton distribution in the near-bottom layer and in the overlying water layers was shown. The near-bottom aggregations of euphausiids and amphipods previously reported by other scientists seem to be related to the attraction of the animals by the submersible’s headlights rather than represent a natural phenomenon.