Numéro du document:
WG-EMM-2025/50
Soumis par:
Louise Emmerson (Australia)
Approuvé par:
Philippe Ziegler (Australia)
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Point(s) de l'ordre du jour
Résumé
- Monitoring predator diets provides insight into the relative availability of prey species and an indication of food web structure. The CCAMLR Ecosystem Monitoring Program (CEMP) monitors key predators, including several penguin species. Stomach lavage is the CEMP standard method for penguin diet monitoring, but some members have ceased using this approach.
- DNA metabarcoding of prey DNA from penguin faeces is a less invasive approach that could provide an alternative or additional method for diet sampling. Improved knowledge of the relative capacity of stomach lavage and DNA metabarcoding methods to detect temporal changes and trends in diet is needed, to understand the comparability of the two methods for long term diet monitoring.
- Here, we directly compare stomach lavage and DNA diet methods. We use both methods to characterise the diet of Adélie penguins Pygoscelis adeliae at Signy Island (South Orkney Islands) during crèche, over eight consecutive seasons (2014-2021).
- The same broad trends in diet were observed using both methods: Antarctic krill Euphausia superba were the main food source in most years, while fish played an important but variable role in the diet. In 2016, both methods detected a particularly high fish component to the diet.
- We recommend developing a standard faecal DNA metabarcoding method for diet analysis, as an additional CEMP standard method to complement Standard Method A8. This should include use of multiple genetic markers to provide both a broad overview of diet and to provide genus- or species-level resolution of key prey groups. This method could be updated in future to incorporate additional genetic markers as needed, and to update taxonomic identifications as new reference DNA sequences become available.
- Our results highlight the capacity from using DNA metabarcoding to obtain dietary data over a broader spatial extent given the relative ease of collecting samples in the field, that could complement long term monitoring using stomach lavage and/or other dietary methods. For example, stomach lavage yielded information on meal mass and prey size, whereas DNA methods identified a greater diversity of prey taxa and provided greater taxonomic resolution.