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

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