Reconstructing the Paleo‐Ecological Diet of Snow Petrels (Pagodroma nivea) From Modern Samples and Fossil Deposits: Implications for Southern Ocean Paleoenvironmental Reconstructions

• Published in: Journal of geophysical research. Biogeosciences 2023-04, Vol.128 (4), p.n/a
• Main Authors: Berg, S., Emmerson, L., Heim, C., Buchta, E., Fromm, T., Glaser, B., Hermichen, W.‐D., Rethemeyer, J., Southwell, C., Wand, U., Zech, M., Melles, M.
• Format: Article
• Language: English
• Subjects: Antarctic zone; Antarctica; Aquatic birds; Archives & records; Biological activity; Carboxylic acids; Chemical composition; Composition; Concretions; Deposits; Diet; Environmental changes; Environmental conditions; fatty acids; Feces; Fish; Food; Foods; Foraging; Foraging behavior; Fossils; Ice environments; Isotopes; Krill; Lipids; Marine crustaceans; Marine ecosystems; Marine environment; Nesting; Nests; Oil; Oil exploration; Organic matter; Pagodroma nivea; paleoclimate; Polynyas; Primary production; Sea ice; Seabirds; Snow; Spatial variations; stable isotopes; Stomach; stomach oil deposits; Temporal variations; Variability
• ISSN: 2169-8953; 2169-8961
• DOI: 10.1029/2023JG007454

Snow petrels (Pagodroma nivea), which are endemic to the Antarctic region, produce proventricular stomach oil from ingested food for feeding purposes but also spit the oil in the immediate surrounds of the nests, where it forms encrustations over time (Antarctic mumiyo). These deposits provide a unique opportunity to understand the paleo‐ecological diet of snow petrels and because the seabirds forage in the ocean, they potentially provide an archive of past marine environmental conditions in the Southern Ocean. For validating methods for reconstructions we use compositional data obtained on modern stomach oils and DNA data from fecal samples of snow petrels. We find that the distribution of carboxylic acid compounds in modern stomach oils and in the fossil deposits are consistent with variable contributions of fish and krill, which are the main constituents of modern snow petrel diet, and allows inference of past changes in snow petrel diet from the fossil record. Analyses of mumiyo deposits from six regions in East Antarctica reveal systematic differences in the isotopic composition of organic matter (δ13C and δ15N) and carboxylic acid patterns. This may suggest regional and/or temporal variability in the composition of snow petrels diet, likely differing in response to the prevailing environmental conditions in the foraging range of the birds, such as sea‐ice variability, polynya activity and primary productivity. Our study provides confidence for using these approaches for broader scale paleo‐studies in the future and for an assessment of the temporal changes and regional variability in snow petrel diet. Plain Language Summary To better understand interactions of biological and physical processes in Antarctic marine ecosystems, we investigate fossil deposits of stomach oil of snow petrels for their use as a geological archive for past environmental changes. The deposits form over time in the surroundings of the nesting cavities of snow petrels, which produce stomach oil from ingested food but also spit it at nest robbers. In fresh oil the lipid and isotopic composition can be traced back to the composition of snow petrel food, such as variable proportions of fish and krill. From comparing the lipid and δ13C‐isotopic composition of modern oil to fossil deposits we suggest it is possible to identify changes in the diet of snow petrels in the fossil record. Since the composition of the diet is closely linked to the prevailing environmental conditions in th