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Marine Ecology Progress Series

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MEPS 735:43-61 (2024)  -  DOI:

Trophic stability and change across a sea ice cover gradient on the western Antarctic Peninsula

A. W. E. Galloway1,*, J. B. Schram2, A. T. Lowe3, R. Whippo1,4, S. Heiser5, K. Iken6, J. B. McClintock7, A. G. Klein8, M. O. Amsler7, C. D. Amsler7

1Oregon Institute of Marine Biology, University of Oregon, Charleston, OR 97420, USA
2Department of Natural Science, University of Alaska Southeast, Juneau, AK 99801, USA
3Tennenbaum Marine Observatories Network, Smithsonian Institution, Edgewater, MD 21037, USA
4NOAA National Ocean Service, National Centers for Coastal Ocean Science, Kasitsna Bay Laboratory, Homer, AK 99603, USA
5Marine Science Institute, University of Texas at Austin, Port Aransas, TX 78373, USA
6College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
7Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35205, USA
8Department of Geography, Texas A&M University, College Station, TX 77843, USA
*Corresponding author:

ABSTRACT: The western Antarctic Peninsula (AP) is experiencing significant changes to sea ice cover, altering the macroalgal cover and potentially affecting the foundation of benthic food webs. We used fatty acid signatures as dietary and physiological trophic biomarkers to test the hypothesis that a gradient of 36-88% mean annual ice cover would affect the trophic ecology of fleshy macroalgae and diverse benthic invertebrate consumers along the western AP. We used SCUBA to collect organisms from benthic rocky nearshore habitats, 5-35 m depth, at 15 study sites during April-May of 2019. There were no consistent ecosystem-scale differences in the nutritionally important polyunsaturated fatty acids or other univariate fatty acid summary categories in either the seaweeds or invertebrates across the ice gradient, but we did find site-level differences in the multivariate fatty acid signatures of all seaweeds and invertebrates. Ice cover was a significant driver of the fatty acid signatures of 5 invertebrates, including 3 sessile (an anemone, a sponge, and a tunicate) and 2 mobile consumers (a sea star and a sea urchin). The multivariate fatty acid signatures of 2 other sea stars and a limpet were not affected by the ice gradient. These results indicate that the trophic ecology and resource assimilation of sessile consumers that are more connected to the macroalgal-derived food web will be more sensitive than mobile consumers to impending changes to annual ice and macroalgal cover along the western AP.

KEY WORDS: Sea ice cover · Western Antarctic Peninsula · Antarctic ecology · Fatty acid signatures · Trophic ecology · Climate change · Benthic ecosystem

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Cite this article as: Galloway AWE, Schram JB, Lowe AT, Whippo R and others (2024) Trophic stability and change across a sea ice cover gradient on the western Antarctic Peninsula. Mar Ecol Prog Ser 735:43-61.

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