Feeding patterns of dominant Antarctic copepods: an interplay of diapause, selectivity, and availability of food

Gut contents and feeding activity of five dominant Antarctic copepods (Calanus propinquus, Calanoides acutus, Rhincalanus gigas, Metridia gerlachei and Microcalanus pygmaeus) were studied from samples collected during several cruises of the RV Polarstern to the eastern Weddell Sea. In summer, feeding activity, estimated as percentage of copepods with food in the guts, was high in all the species, and diatoms dominated all gut contents. In winter, C. acutus was trophically inactive, and C. propinquus and R. gigas considerably decreased their feeding activity, while a decrease in feeding of M. gerlachei and M. pygmaeus was less pronounced. Unidentified mass dominated gut contents in winter, supplemented by phytoplankton and protozoans. Prior to the spring bloom, feeding activity of C. acutus was low, with unidentified food predominating, while carnivory was important in actively feeding C. propinquus. Rhincalanus gigas tended to be more carnivorous than C. acutus, however with less feeding activity than C. propinquus. Seasonal changes in feeding patterns are discussed.