MEPS 482:17-28 (2013)  -  DOI:

Food web structure of a coastal Arctic marine ecosystem and implications for stability

Bailey C. McMeans1,*, Neil Rooney2, Michael T. Arts3, Aaron T. Fisk

1Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Ave., Windsor, Ontario N9B 3P4, Canada
2Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
3National Water Research Institute, Environment Canada, 867 Lakeshore Road, PO Box 5050, Burlington, Ontario L7R 4A6, Canada

ABSTRACT: There is little doubt that Arctic ecosystems will continue to face unprecedented change in the coming decades. The identification of food web structures that confer stability to these systems is, therefore, a priority. Here, we use stable isotopes and fatty acids to resolve the food web structure of a seasonally ice-covered fjord (Cumberland Sound, Baffin Island, Canada) sampled in late summer. We show that the food web is structured such that upper trophic levels couple separate energy channels (based on phytoplankton or macroalgae), a previously documented food web structure that has been linked with stability in temperate ecosystems, but never established in a seasonally dynamic, ice-covered ecosystem. Herbivorous zooplankton (e.g. Calanus hyperboreus) relied exclusively on phytoplankton, whereas herbivorous benthos used either phytodetritus (e.g. Hiatella arctica) or macroalgae (e.g. Tectura testudinalis), supporting the existence of separate energy channels. Upper trophic level fishes and marine mammals relied more heavily on phytoplankton- than macroalgal-derived carbon (58 to 100% reliance on phytoplankton), but 6 out of 8 species sampled derived energy from both carbon sources. Since benthic invertebrate predators used both phytodetrital- and macrolgal-based resources, the coupling of separate energy channels was also iterated within the benthos. The temporally pulsed nature of phytoplankton production, characteristic of Arctic seas, indicates that Arctic consumers also act as couplers of resources in time because phytoplankton- and detrital-based carbon would likely reach upper trophic levels earlier and later in the season, respectively. Potential changes in the relative production of macroalgae and phytoplankton under climate change scenarios could impact the stability-promoting food web structure reported here.

KEY WORDS: Resource coupling · Ecological patterns · Arctic marine ecology · Food web · Stable isotopes · Fatty acids · Macroalgae · Climate warming

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Cite this article as: McMeans BC, Rooney N, Arts MT, Fisk AT (2013) Food web structure of a coastal Arctic marine ecosystem and implications for stability. Mar Ecol Prog Ser 482:17-28.

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