科研之友
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摘要
Carbon and nitrogen stable isotope analyses were performed on modern and Holocene Adelie penguin guano samples collected from ornithogenic soils along the Scott Coast (Southern Victoria Land, Antarctica), from Cape Irizar to Dunlop Island, and at Cape Bird (Ross Island). Guano samples also were sieved and sorted under stereomicroscope in order to select penguin dietary remains, such as fish bones and otoliths. Carbon and nitrogen stable isotope composition, coupled with the taxonomic identification of fish otoliths from Scott Coast Holocene samples, indicated a mainly fish-based diet for this area, with Pleuragramma antarcticum as the most eaten prey throughout the investigated period (from 390 cal BP to ca 7300 cal BP). The isotopic values of Ross Island samples (from modern to 3850 cal BP) showed a krill consumption increase in the samples younger than 2000 cal BP, with the maximum in modern samples. Scott Coast and Ross Island Holocene samples showed delta C-13 and delta N-15 trends similar to those previously published from Terra Nova Bay (northern Victoria Land), whereas modem samples from Ross Island have similar delta N-15 composition but different delta C-13 values. This delta C-13 divergence started at ca 2000 BP and follows the abandonment of the Scott Coast colonies. The delta C-13 trend observed in Ross Island and Terra Nova Bay samples and the abandonment of the Scott Coast colonies could suggest the stability and the persistence of the previous oceanographic conditions (i.e. polynya) for the Terra Nova Bay area and the establishment of new conditions for water circulation in the Southern Ross Sea since similar to 2000 BP when persistent sea-ice sealed the Scott Coast.
- 出版日期2014-2-1
