Fish otoliths from ornithogenic soils for investigating Holocene Adélie Penguin diet variation in Victoria Land, Antarctica.

• Main Authors: LORENZINI S., OLMASTRONI S., SALVATORE, MARIA CRISTINA, BARONI, CARLO
• Other Authors: -, Woehler EJ, Lorenzini, S., Olmastroni, S., Salvatore, MARIA CRISTINA, Baroni, Carlo
• Format: Conference Object
• Language: English
• Published: 6th International Penguin Conference Committee 2007
• Subjects: Adelie penguin; fish otolith; ornitogenic soil; diet; Holocene; Victoria Land; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/11568/112322

Paleodiet studies on ornithogenic soils are valuable for investigating the relationship between ecoenvironmental trend of Adélie penguins and global environmental changes. Ornithogenic soils consist of accumulation of droppings, feathers, egg fragments and bird remains. Their thickness depends on the age of establishment: the thicker the soil, the older the colony. Organic soils occur in active Adélie penguin colonies and at their margins, thus testifying to the presence of abandoned nesting sites. Abandoned (relict) Adélie penguin colonies have been discovered in Victoria Land (Antarctica) in areas where penguins do not breed at present. Soils retained in relict colonies have been radiocarbon dated and supplied relevant data on the Holocene environmental history of Victoria Land. Being resistant to digestion and erosion, hard parts of penguin prey such as fish bones, otoliths and squid beaks are preserved in ornithogenic soils. Otoliths allow the identification and size-estimation of prey eaten. More than 1000 otoliths (about 500 individuals) have been identified as Pleuragramma antarcticum (85%), Pagothenia sp. (2.2%) Trematomus bernacchii (1.7%), Trematomus scotti (0.2%); about 10% of the otoliths remained unidentified. Frequency distribution of P. antarcticum sizes shows that 73.6% was 40-80 mm. Their age ranges from about 8000 yrs BP to the present.