Relationship between Respiration Rate and Body Weight in Arctic Copepods at Subzero Temperature

Abstract

The dependence of the respiration rate (R) on an animal’s weight (W) is described by the equation R = aW ^b, where the exponential coefficient b is usually taken equal to 3/4. However, several authors have indicated that the value of coefficient b may vary with temperature changes, as well as during ontogeny. In Arctic seas, copepods spend most of their lives at temperatures below or close to zero. Meanwhile, there are very few respiration rate measurements at temperature ≤ 0°C, which does not allow us to estimate the value of coefficient b at subzero temperature. The study was carried out on three cruises of the R/V Akademik Mstislav Keldysh in the Siberian Arctic seas in 2018–2020. Copepods caught from the sea were adapted to the experimental temperature and placed in tightly capped vials filled with filtered seawater for 24 h. The oxygen concentration was measured with a fiber-optic oxygen probe. The results of 120 respiration rate measurements and 111 body carbon measurements in five species of copepods at a temperature of –1.5°C are presented. The obtained relationship between body carbon content (W) and prosome length (L) is described by the equation W = 6.982L^3.221, and the dependence of respiration on body weight is described by the equation R = 0.077W ^0.753. No effect of subzero temperature on coefficient b was revealed. The parameters of regression R(W) did not change with the ontogenetic development of Calanus glacialis.