MEPS 306:31-40 (2006)  -  doi:10.3354/meps306031

Holocene variation in the Antarctic coastal food web: linking δD and δ13C in snow petrel diet and marine sediments

D. G. Ainley1,*, K. A. Hobson2, X. Crosta3, G. H. Rau4, L. I. Wassenaar5, P. C. Augustinus6

1H. T. Harvey & Associates, 3150 Almaden Expressway, Suite 145, San Jose, California 95118, USA
2Environment Canada, Canadian Wildlife Service, 115 Perimeter Road, Saskatoon, Saskatchewan S7N 0X4, Canada
3UMR-CNRS 5808 EPOC, Avenue des Facultés, Université de Bordeaux, 33405 Talence Cedex, France
4Institute of Marine Sciences, University of California, Santa Cruz, California 95064, USA
5Environment Canada, National Water Research Institute, 11 Innovation Place, Saskatoon, Saskatchewan S7N 3H5, Canada
6Departments of Geography and Geology, University of Auckland, Auckland 1030, New Zealand

ABSTRACT: Here we present first time evidence for concordant variation in the isotopic signature at both the base and the upper levels of the Antarctic coastal food web during the Holocene. Laminae in sub-fossil deposits of snow petrel Pagodroma nivea stomach oil, known as mumiyo, were collected from nest-sites in the Bunger Hills, East Antarctica. Mumiyo layers were sub-sampled, radiocarbon-dated, and analyzed for δ13C and δD. The obtained values were compared to isotopic variability among layers of an ocean sediment core collected, and similarly dated, in nearby Dumont D’Urville Trough. Overlapping records extended from about 10160 to 526 calendar years before present (cal yr BP). Mumiyo δD values remained relatively constant throughout the sampled period, in accordance with data from nearby ice cores. For 13C, both mumiyo and sediment were enriched during the warmer mid-Holocene (ca. 7500 to 5500 cal yr BP). Isotopic concordance between the core and the mumiyo, and a significant correlation between mumiyo δD and δ13C, suggest that past δ13C variation in plankton was transferred through diet to higher trophic levels and ultimately recorded in stomach oil of snow petrels. Divergence in signals during cold periods may indicate a shift in foraging by the petrels from 13C-enriched neritic prey to normally 13C-depleted pelagic prey, except for those pelagic prey encountered at the productive pack-ice edge during cooler periods, a shift forced by presumed greater sea-ice concentration during those times. Other air-breathing predators would likely respond in the same way.

KEY WORDS: Antarctica · Holocene climate change · Food webs · Isotopic analysis · Mumiyo · Pagodroma nivea · Sediment cores · Snow petrel

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