Metabolism and chemical composition of zooplankton from 500 to 5,000 m depth of the western subarctic Pacific Ocean

Abstract

Respiration (=oxygen consumption) rates of 28 zooplankton species belonging to 10 taxa from 500 to 5,000 m depth of the western subarctic Pacific Ocean were determined as 0.027–0.44 μLO2 mg dry mass−1 h−1 at in situ temperatures (1.5–3 °C), which are 80 % lower than the rates of the epipelagic Antarctic zooplankton with similar body mass and at a comparable temperature. In terms of adjusted metabolic rate to 1 mg body N (AMR; μLO2 mg N−0.8 h−1) at 1 °C, the present results (mean 1.66) fall well within the range (0.84–3.32) reported for copepods, chaetognaths, and mixed crustaceans from 500 to 7,000 m in the subarctic Pacific Ocean and Antarctic waters. Judging from their body C:N elemental ratios and ash-free dry mass (=organic matter) data, the major component of organic matter is deduced to be protein (C:N = 3.4–8.1, by mass) for 19 out of 28 species and lipids (C:N = 8.6–13.0) for the remaining 9 species.