Summer and winter diet of four carnivorous copepod species around South Georgia
The natural diets of adult female Euchaeta antarctica, E. farrani, E. rasa and E. biloba, as well as male and female copepod stage V E. antarctica, were compared through gut content analyses. Copepods of variable size dominated the diet of all predators during both seasons (46 to 99 % of all food items). Mean number of prey per predator (0.9 to 8.6), as well as the distribution of predators with different numbers of prey in the gut, indicated no general decrease in feeding by Euchaeta spp. during the Antarctic winter. Diet of adults was broad and overlapping in both seasons. During summer, copepod nauplii and the small copepods Drepanopus forcipatus and Oithona spp. dominated the diet of CV E antarctica in the upper 200 m. Nauplii were hardly taken at all by adult E. antarctica in that depth interval. During winter D. forcipatus dominated the diets of both CV and adult E antarctica, and of E. biloba. Among CV female E. antarctica 13 % of individuals took 44 % of all food items during winter. This emphasises the patchy nature of feeding in the sea and indicates the importance of adequate sampling scales and sample size in feeding studies.