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Marine Ecology Progress Series

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MEPS 317:111-126 (2006)  -  doi:10.3354/meps317111

Feeding ecology and metabolism of the Antarctic cydippid ctenophore Callianira antarctica

Kerri M. Scolardi1,3,*, Kendra L. Daly1, Evgeny A. Pakhomov2,4, Joseph J. Torres1

1 College of Marine Science, University of South Florida, 140 Seventh Avenue South, St. Petersburg, Florida 33701, USA
2 Department of Zoology, Faculty of Science and Technology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
3 Present address: Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, Florida 34237, USA
4 Present address: Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, British Columbia V6T 1Z4, Canada

ABSTRACT: The chemical composition, metabolism, and feeding ecology of the cydippid ctenophore Callianira antarctica (Chun 1897) were investigated during autumn and winter 2001 and 2002 in the vicinity of Marguerite Bay, an embayment on the western Antarctic Peninsula shelf. C. antarctica had relatively high carbon (C) and nitrogen (N) values (average: 8.4% C and 1.8 % N [% dry weight, DW]), further suggesting that polar ctenophores are more C-rich than tropical species. Winter oxygen consumption and ammonium excretion rates ranged from 0.059 to 0.411 µl O2 mg–1 DW h–1 and 0.043 to 2.22 nmol N mg–1 DW h–1, respectively, at 0°C. Calanoid copepods, larval and juvenile Antarctic krill Euphausia superba, and a mixture of prey were offered to ctenophores during feeding incubations. Ingestion rates based on preliminary feeding experiments were linearly related to prey densities, with rates ranging from 9 to 39 prey ind.–1 d–1 and from 3.5 to 4.0 prey ind.–1 d–1 for 1 larger and 1 smaller C. antarctica, respectively. Daily rations varied between 22 and 136% of body C for the larger ctenophore and 6 to 22% of body C for the smaller individual. Digestion time (median: 11.5 h) was dependent on prey elemental content and prey number, and independent of ctenophore size. Gut content analyses indicated that C. antarctica preyed predominantly on larval euphausiids and copepods. Diver observations, net collections, and diet analyses suggest that this species is an opportunistic predator that feeds both during the day and night, and appears to be well adapted to the prey patchiness found in Antarctic waters.

KEY WORDS: Antarctic zooplankton · Ctenophore · Krill · Copepod · Digestion time · Daily ration · Gut contents · Overwintering

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