| Summary: | Dissertação de mestrado em Ecologia, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra. Antarctic and Southern Ocean marine ecosystems have been changing for the past 30 years, along with the global climate change. The most evident changes are on the Western Antarctic Peninsula, which is warming four times faster than the average rate of Earth‘s overall warming. Within the Antarctic Peninsula region, one of the penguin species used to monitor Southern Ocean food web changes is the chinstrap penguin (Pygoscelis antarctica). The main objective of this study is to assess the feeding ecology of chinstrap penguins in Livingston Island. This is done by comparing the diets from adult chinstrap penguins (through fecal samples; scats) and chicks (through stomach contents from naturally died chicks). To complement these analyses, different tissues (i.e. feathers, blood, flesh and nails) were collected from adult penguins and dead chicks and used for stable isotope analyses of 15N and 13C. Also a snapshot of the marine food web around Livingston Island is provided, in order to assess chinstrap penguin trophic level in comparison with other organisms through the stable isotopic analyses of typical, key organisms found in Livingston Island (i.e. algae, krill, seabirds, seals). Crustaceans, specifically Antarctic krill comprised the diet 100% by frequency of occurrence, by mass and by number of both adults and chicks chinstrap penguins. This confirmed that Antarctic krill dominates the diet of chinstrap penguins at least during the breeding period. The mean size of collected Antarctic krill was 38.66 ± 2.56 mm for adults and 39.87 ± 2.69 mm for chicks. Different tissues reflect different time scales of stable isotope incorporation. For adults, feathers were more enriched in stable isotope ratios of nitrogen and carbon than blood, and reflect the diet form the previous year after the breeding season, while blood reflects the most recent diet. High significant ...
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