JPR Advance Access originally published online on June 5, 2007
Journal of Plankton Research 2007 29(8):727-737; doi:10.1093/plankt/fbm052
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Variability in the trophic position of larval fish in a coastal pelagic ecosystem based on stable isotope analysis
1 Northwest Atlantic Fisheries Centre, Fisheries And Oceans Canada, PO BOX 5667, St John'S, Newfoundland and Labrador, Canada A1C 5X1 2 Department Of Biology And School Of Earth And Ocean Sciences, University Of Victoria, Po Box 3020, Station CSC, Victoria, British Columbia, Canada V8W 3N5
* Corresponding Author: pepinp{at}dfo-mpo.gc.ca
Received on December 15, 2006; accepted on May 30, 2007
K.J. Flynn
| Abstract |
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We used stable isotopes of carbon (C) and nitrogen (N) to investigate the trophic position of six species of larval fish in the pelagic ecosystem of coastal Newfoundland. Isotope profiles from phytoplankton, net plankton and macrozooplankton were consistent with previous studies. All species of larval fish showed a length-dependent shift in
13C that indicates a move to a pelagic diet from the combined pelagic and demersal eating habits of the adult spawners. The trophic position of four larval fish species (American plaice, yellowtail flounder, cunner, radiated shanny) was consistent with them feeding primarily on copepods, as expected from stomach content analysis. The
15N-based trophic position of larval witch flounder and capelin indicates that they feed significantly on phytoplankton and heterotrophic protists from the microbial loop, respectively; this evidence contrasts with stomach content analysis. Although links between larval fish and the microbial loop are not considered as common as is the link with crustacean zooplankton, this and other studies challenge the long-held belief that marine fish larvae feed effectively exclusively on copepods.
Communicating editor: K.J. Flynn