Abstract
Grazing rates of copepodite stage V Calanus finmarchicus and copepodite stage V and adult females C. hyperboreus fed diatoms, colonies and solitary cells of Phaeocystis pouchetii were estimated during May using both a continuous open flow system and measurement of plant pigments in gut contents. Both Calanus species fed actively on colonies and solitary cells of P. pouchetii. The results suggest that solitary cells of P. pouchetii may be at least as suitable as the diatom Chaetoceros furcellatus as a food source for Calanus species from fjord areas in northern Norway. Colonies of P. pouchetii may also be an important food source for these copepods. Estimated daily rations varied from 0.4 to 14.6 % of body carbon in food concentrations from 77 to 1810 μg C per litre.
