Seasonal trophic ecology of the invasive crab Percnon gibbesi (Brachyura, Plagusiidae) in the southwestern Mediterranean: Insights from stomach contents and stable isotope analyses

The invasive sally lightfoot crab Percnon gibbesi (H. Milne Edwards, 1853) has spread among the coasts of the Mediterranean Sea, including the coasts of Annaba Gulf (Algeria). Investigating the trophic position of the species and looking for the seasonal variations in the diet of this alien decapod was the aim of this study. To do this, samples of P. gibbesi were collected along Annaba coasts within a year. The traditional stomach content analysis (SCA) was integrated to the stable isotope analysis (SIA) of nitrogen and carbon to provide a comprehensive evaluation of the feeding ecology of P. gibbesi, and its within-year variability. Results highlighted, for the first time, significant seasonal variation in P. gibbesi diet, improving our understanding of its trophic plasticity and potential dietary overlaps with other herbivore species. Its feeding plasticity is an asset in the successful expansion of its distribution. Relating its diet composition through the different seasons with the interactions with native herbivores will be essential to fully appreciate the impact of the spread of P. gibbesi in the Mediterranean Sea.