MEPS 615:31-49 (2019)  -  DOI: https://doi.org/10.3354/meps12923

ABSTRACT: Arctic kelp belts, made of large perennial macroalgae of the order Laminariales, are expanding because of rising temperatures and reduced sea ice cover of coastal waters. In summer 2013, the trophic relationships within a kelp belt food web in Kongsfjorden (Spitsbergen) were determined using fatty acid and stable isotope analyses. Low relative proportions of Phaeophyta fatty acid trophic markers (i.e. 20:4(n-6), 18:3(n-3) and 18:2(n-6)) in consumers (3.3-8.9%), as well as low 20:4(n-6)/20:5(n-3) ratios (<0.1-0.6), indicated that Phaeophyta were poorly used by macrozoobenthos as a food source, either fresh or as detritus. Relatively high δ¹³C values measured in macrozoobenthos (-22.5 to -16.1‰) ruled out an important role of erect Rhodophyta, which were much more ¹³C depleted (-37.1 to -35.8‰). Instead, δ¹³C values and relatively high abundances of typical diatom (14:0, 16:1(n-7), 20:5(n-3)) and flagellate (18:4(n-3), 22:6(n-3)) fatty acid trophic markers in consumers pointed out an important use of microalgae, likely of pelagic and benthic origin (i.e. senescent phytoplankton bloom, eroded epiphytes and suspended epilithic material). The use of these food resources may be fostered by their trapping under the kelp canopy.

KEY WORDS: Food web · Polar coastal ecosystem · Trophic markers · Macrofauna · Macroalgae · Detritus

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Cite this article as: Paar M, Lebreton B, Graeve M, Greenacre M, Asmus R, Asmus H (2019) Food sources of macrozoobenthos in an Arctic kelp belt: trophic relationships revealed by stable isotope and fatty acid analyses. Mar Ecol Prog Ser 615:31-49. https://doi.org/10.3354/meps12923 Export citation Share:    Facebook - - linkedIn