Vol. 84:255-264,1992
MARINE ECOLOGY PROGRESS SERIES
Published August 13

Seasonal differences in the content of Oikopleura
vanhoeffeni and Calanus finmarchicus faecal
pellets: illustrations of zooplankton food web
shifts in coastal Newfoundland waters

Juanita L. Urban 1 & 2, Cynthia H. McKenzie 1, Don Deibel 1 & 2

1 Ocean Sciences Centre,

2 Department of Biology, Memorial University of Newfoundland, St. John's,

Newfoundland, Canada A1C 5S7

ABSTRACT: Faecal pellet contents from Oikopleura vanhoeffeni and Calanus finmarchicus were examined in the spring, summer, fall and winter. Contents varied seasonally, resembling available particles in the water column. This indicated a temporal succession from a diatom-based food chain in the winter and spring to one based on the microbial loop in the summer and fall. Bacteria, cyanobacteria, Anabaena sp., choanoflagellates, ciliates, and heterotrophic dinoflagellates were found in the faeces, suggesting a direct link between the microbial loop and both crustaceans and pelagic tunicates.