Monitoring variability in predator diets can highlight key parameters for understanding and managing marine ecosystems. Penguin diets provide useful indicators of ecosystem variability and several species, including Adélie penguins (Pygoscelis adeliae), are included in the CCAMLR Ecosystem Monitoring Programme, which aims to detect and record significant changes in critical marine ecosystem components.
Current standard methods include using stomach lavage to identify prey composition and mass. However, there is increasing interest in less invasive methods. Analysis of prey DNA in faeces is one potential approach to complement existing diet monitoring. Improving knowledge of the differences between stomach lavage and molecular methods, in terms of resolution, biases, and the types of biodiversity observations possible, will be important as molecular methods become more widely used. Comparative datasets will facilitate recommendations for development and adoption of standardised DNA diet monitoring protocols.
To directly compare molecular and lavage methods, we examined diets of Adélie penguins during crèche at Signy Island, South Orkney Islands, over eight seasons (2014-2021). We show that faecal DNA analysis provides an opportunity to establish a complementary alternative method for long-term diet monitoring. This could substantially enhance the inclusion of dietary observations in ecosystem monitoring, contributing to Antarctic marine biodiversity conservation.