Vertical distribution of Zooplankton over the region of hydrothermal activity at 9°50′ N (the East Pacific Rise)

The plankton distribution in the entire water column and in the near-bottom layers above the deep-water vent field at 9 degrees 50' N on the East Pacific Rise was studied with use of Mir deep-sea manned submersibles and BR plankton nets. No near-bottom peak of the abundance of planktonic animals was revealed there; meanwhile, an increase in the number of larvacean shelters was found near the boundaries of the hydrothermal plume. The importance is noted of the significance of the plume's hydrological structure for the fine distribution of larvaceans. It is shown that one of the expected mechanisms of the influence of hydrothermal plumes on oceanic plankton (the redistribution of the animals already existing in the water column) really operates in nature.