Preliminary analysis of abandoned Holocene penguin rookeries at South Shetland Islands, Antarctica

ACIOSTA HOSPITALECHE, CAROLINA; GELFO J. N.; REGUERO, M.

Hobart OSC

Congreso; SCAR Open Science Conferences; 2020

Scientific Committee on Antarctic Research

Penguins are climatic sensitive seabirds that establish colonies along the marine coasts of Antarctica since the Paleocene (60 million of years ago) to which they return every year during the breeding season. Accumulations of bones, pebbles, and guano constitute rookeries, that condense and transform into ornithogenic soils preserving evidence of nesting constitution, penguins diet, and biological interactions in the past. We prospected the 25 de Mayo/King George Island (South Shetland Islands) looking for the reported rookeries in the Potter Peninsula (Pingüi could not be re-located following the published coordinates). Pingfo II corresponds to raised marine deposits with bones dated in 7780 ± 60 yr BP and 7600 ± 80 yr BP without modern colonies at the top. Ornithogenic soils were not detected, and the disarticulation and weathering of bones indicate transport and accumulation in a high energy beach. Pingfo I is a more elevated recolonized area within ZAEP 132 with hundreds of Pygoscelis adeliae at the top since 2012 (monitoring program Instituto Antártico Argentino). Seven levels yield bones dated in 5750 ± 40 yr BP and 5840 ± 40 yr BP. The abundance of bones of different ontogenetic stages, the presence of eggshells, seaweeds, and pebbles, and the lack of evidence of transportation suggest that the breeding colony was settled in this area. We continue with the sieved sediment and consolidated blocks rich in organic material processing in the lab, in the search for traces of penguins diet, and small organisms that could offer paleoclimatic, paleoecological, and pedological information.