Importance of ciliates as prey of the euphausiidEuphausia pacificain the NW North Pacific

We investigated the feeding ofEuphausia pacificaon ciliates, especially naked ciliates, in laboratory and field experiments in which culturedStrombidium conicum, or natural food assemblages, or both were given, and estimated the importance of ciliates as prey.E. pacificaingested culturedS. conicumat rates of 0.04 to 0.07 μg C krill–1h–1at low ciliate concentration and 1.01 to 3.24 μgC krill–1h–1at high ciliate concentration, whenS. conicumwas given as the sole prey. The daily ration on naked ciliates ranged from 0.02 to 1.8% of body carbon when natural food assemblages enriched withS. conicumwere given, and from 0.05 to 2.3% of body carbon whenS. conicumwas given as the sole prey. Our results provide indirect evidence thatE. pacificaingests naked ciliates and plays a role in linking microbial food webs to the classical grazing food chains.