A New Hydrostatic Pressure Apparatus for the Study of Zooplankton throughout Its Life History

Abstract

A hydrostatic pressure apparatus for the study of zooplankton throughout its life history from egg to adult was developed. The feature of this apparatus is as follows. (1) Pressure increases gradually. (2) A maximum of nine zooplanktons or their eggs can be observed independently at once. (3) This apparatus is small and easy to carry. The influence of pressure on the egg-hatching of Calanus sinicus was investigated using this system. The egg-hatching success decreased significantly with increasing pressure. Eggs would not survive if they did not hatch with the depth of water of 100 m or less.