Climate change creates multiple stressors for organisms in Arctic ecosystems, such as key zooplankton species of the genus Calanus. Here, we quantified the mortality and fecal pellet production rate of Calanus finmarchicus and C. glacialis from Disko Bay, West Greenland, with respect to temperature and salinity. The 2 species were exposed to temperatures of 0, 5 and 10°C and a salinity range from 5 to 60. C. glacialis had a significantly lower mean lethal concentration (LC50) of 9 with a standard error of 1.98 at the lowest temperature, at salinities below in situ salinities, compared to C. finmarchicus (14 ± 0.35). At high temperatures, C. glacialis LC50 was significantly lower
than that at 0°C. At high salinities, the 2 species did not have significantly different LC50 values. The fecal pellet production rates were quantified at saturated food concentration (>400 μg C l–1). No impact of salinity was observed between salinities of 25 and 40. Increases in fecal pellet production rates were observed at the limits of this range, indicating a physiological stress response.
Within the 25–40 salinity range, fecal pellet production rates increased exponentially with temperature for C. finmarchicus (average Q10 = 1.9 ± 0.18) in the temperature range of 0–10°C, while for C. glacialis, they peaked at 5°C (average Q10 between 0 and 5°C was 2.19 ± 0.15). Our results demonstrate a high physiological plasticity of both Calanus species with respect to salinity. C. glacialis will be more tolerant in a future surface freshening scenario, although this advantage seems to be impaired at temperatures above 5°C.