RESPIRATION OF A VERTICALLY MIGRATING MARINE CRUSTACEAN <i>EUPHAUSIA PACIFICA</i> HANSEN1

Abstract

Results from acclimation experiments and experiments performed on freshly caught specimens indicated that Euphausia pacifica is adapted to temperatures between 5–10C off Oregon, but not to 15C. The temperature range common to Oregon waters through all seasons is about 5–10C, while 15C water is found only at the surface in summer. Animals migrating to 600 m (around 5C) apparently exhibit slightly lower respiratory rates at all temperatures encountered than animals migrating to 250 m or less (around 10C). Deep‐migrating animals may compensate for temperatures around 15C. Euphausiids descending to 250 m or less make up the bulk of the population and apparently compensate very little for temperatures around 15C. A temporal and spatial picture of euphausiid respiration off Oregon is presented that may be applicable in energy transfer studies.