Influence of temperature, habitat and body mass on routine metabolic rates of Subantarctic teleosts

Abstract

Subantarctic notothenioids are exposed to wider variations in temperature than those encountered in the Antarctic Ocean, the ancestral environment of the group. In this study the influence of temperature on the routine metabolic rate of Subantarctic teleosts was described and the results were compared with routine metabolic rates of species with different geographical distributions, exploring the concept of Metabolic Cold Adaptation (MCA). Oxygen consumption (VO_2R) was determined as an estimate of the routine metabolic rate for the following Subantarctic notothenioids: Paranotothenia magellanica, Patagonotothen sima, Eleginops maclovinus, Harpagifer bispinis and the eelpout Austrolycus depressiceps. In all studied species and tested temperatures, body mass and VO_2R showed a positive correlation. A drop in the temperature from 10 to 2°C produced a significant reduction of VO_2R values with a Q_{10 (10-2)} varying between 4.69 and 9.54. VO2R values were related to species habitat: pelagic species reached the highest values of VO_2R, while sluggish species had the lowest ones. We can conclude that the metabolic rates of these species of Subantarctic fish do not show MCA at the investigated temperatures.