Benthic food-web structure of an Arctic fjord (Kongsfjorden, Svalbard)

Abstract

Describing trophic relationships is fundamental for understanding ecosystem function and evaluating how these functions may vary under natural and human-induced changes in system drivers. The food-web structure (food-chain length, primary carbon sources, trophic positions of dominant functional groups) of an Arctic benthic community was investigated using stable isotopes of carbon and nitrogen. Suspended organic matter, benthic fauna, and benthic-feeding fishes and seabirds were collected from two locations during three seasons in and just outside of Kongsfjorden, Svalbard. Stable isotope ratios suggested relatively little variability in food-web structure over the temporal and spatial scales studied. A single food source (pelagic phytoplankton) appeared to predominate throughout the year regardless of location. Further, our results confirmed findings from other areas indicating that Arctic food chains are long, consisting of between 4 and 5 trophic levels. The prevalence of deposit-feeding taxa may buffer seasonal signals, and the highly advective nature of Kongsfjorden, and perhaps many open (non-silled) fjords, is likely responsible for similar food-web structure, despite spatial variability in benthic community composition.

Keywords:

• Functional group
• seasonality
• spatial variability
• stable isotopes
• trophic structure

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We would like to express our gratitude for all the assistance of scientists involved in the COPOL project, and especially K. Borgå, G. W. Gabrielsen, and H. Hop. COPOL is a Norwegian International Polar Year project funded by the Norwegian Research Council (project no. 176073/S30). This work could not have been performed without excellent work by the officers and crews of the research vessels Jan Mayen, Lance, and Teisten. E. Oug assisted with assignment of trophic groups. We also acknowledge support from Akvaplan-niva and Kings Bay AS.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark