Oxygen consumption during simulated vertical migration in Mysis relicta (Crustacea, Mysidacea)

Abstract

When Mysis relicta was induced to swim at speeds of 1.0 and 1.6 cm/s, which are similar to observed vertical migration rates in Lake Ontario, there was no significant (P <.05) increase in oxygen consumption over the 'routine' rate of 5.28 μg oxygen per animal per hour for a 5-mg animal (dry weight). At higher swimming speeds (2.1 to 3.6 cm/s) an increase in oxygen consumption to 1.2 times the 'routine' rate was demonstrated. Exopodite beat rate increased from 3.7 cycles per second under 'routine' conditions to 5.3 cycles per second al a swimming speed of 3.6 cm/s. Increased external salinity under 'routine' conditions resulted in decreased rates of oxygen consumption from 5.28 μg oxygen per animal per hour at 0‰, to 3.28 μg oxygen per animal per hour at 15‰ for a 5-mg animal. At 25‰ and 30‰, oxygen consumption remained about the same as at 15‰. The results add further support to earlier theories that postulate a negligible "cost" for vertical migration.