Metabolic activity of zooplankton from the Antarctic Ocean

Abstract

Eight species of live zooplankton were transported from the Antarctic Ocean to a tropical laboratory in Queensland, Australia. Their respiration and ammonia excretion rates measured at - 0.5º C were in the order of 0.15-0.55 µl O₂/mg dry wt. h and 0.002-0.06µg N mg dry wt. h, respectively. As an indirect estimate enzyme activity of the respiratory electron transport system (ETS) was determined on frozen specimens of 15 zooplankton species brought back from the Antarctic Ocean. The ratio of ETS activity to respiration rate measured in this study was 1.863 ± 0.738 (n = 12). The respiration rates thus directly and indirectly obtained were in agreement with results of previous workers.

Effect of temperature on respiration and ammonia excretion rates were examined on two selected animal groups of zooplankton- copepods belonging to the family Calanidae and euphausiids of the genus Euphausia- and the results were compared with those for species from other seas where the temperature varies from 5.0 to 27.6ºC. From this comparison, acceleration of the rate (standardized to 1 mg dry wt of body) by the increase of temperature (expressed as a Q₁₀ value) was 2.18 for respiration rate and 2.58 for ammonia excretion rate.