Omnivory by Euphausia pacifica: the role of copepod prey

Abstract

Adult E. pacifica obtain a maximum C-specific ration of 8.8% d-1 [day-1] from the centric diatom Thalassiosira angstii and 0.45 % d-1 from the copepod Pseudocalanus sp. E. pacifica exhibits a sigmoidal or stabilizing functional response to diatoms but not to copepods. Adult copepods may be attacked and injured by E. pacifica but they are suboptimal prey item for this omnivore.