Temperature dependence of respiration rates in active and diapausing Arctic copepods: new empirical data and ecological aspects

ABSTRACT Respiration, as one of the most important processes sustaining life of all organisms, has been the subject to extensive study. Measurements of respiration rates of Arctic copepods at their habitat temperatures are scarce. The present study filled this gap with measurements of respiration at −1.5 to 6°C in onboard experiments (428 measurements) in the Siberian Arctic seas. For the first time thermal dependence of respiration of Calanus glacialis and Calanus hyperboreus was obtained during the state of diapause, which makes up an important part of their life cycle. Activation energy in Calanus spp. was higher (0.85–0.87 eV) than usually assumed (0.6–0.7 eV). Higher thermal sensitivity is suggested to be related to a stenothermic life history mode. Carbon-specific respiration rate in diapausing Calanus spp. was 3.6–3.7 times lower than in active copepods, while thermal sensitivity (activation energy and Q10) was similar. Potential duration of diapause of the older stages of the Arctic Calanus spp. is more than a year at −1.5°C and decreasing with increasing temperature.