A laboratory investigation into the effects of hydrostatic pressure on the vertical migration of planktonic Crustacea

A laboratory-scale vertical migration, using adult Daphnia magna, was observed within an observational pressure vessel. The animals exhibit a clearly defined movement along the water column in response to an overhead light regime. The hydrostatic pressure was increased to 41.5 bar (600 psi) during the course of a migration. a short lived increase in swimming rate was observed, but the pattern of the migration was quickly restored; the migration continued at the high ambient pressure. The response of D. magna to light does not appear to be affected by high pressure.