Composition and variation in the diet of the invasive blue crab

Abstract

This study examines the dietary composition and variation in the feeding of the invasive blue crab Callinectes sapidus in Mellah Lagoon, a safeguarded coastal habitat in northern Algeria. During a one-year period (February 2021–March 2022), 287 stomachs from adult crabs were examined quantitatively and qualitatively, considering sex, reproductive condition, and season. Yearly average stomach vacuity rate was 37.6%, with substantial seasonal variations and significant differences between ovigerous and non-ovigerous females. Prey items were classified into nine taxonomic groups, with the majority being Arthropods (37.42%), followed by unidentified organic matter (27.46%), mollusks (15.47%), teleost fish (11.49%), and plant material (7.8%). A significant level of trophic similarity was observed between males and females. In contrast, the correlation between ovigerous and non-ovigerous females was positive but not statistically significant. Seasonal comparisons also showed non-significant correlations between winter and autumn and between winter and spring. The estimated trophic level (3.3) supports the classification of C. sapidus as an opportunistic omnivore.