Feeding habits of the invasive Atlantic blue crab Callinectes sapidus (Decapoda, Brachyura, Portunidae) in a temperate European estuary

Abstract

The Atlantic blue crab, native from the east coast of the American continent, is a portunid, estuarine crab that has been recently considered invasive in many areas of the European and African continents, being cited in the Guadalquivir estuary in 2017 for the first time. The feeding habits of the Atlantic blue crab were studied as predictor of food web interactions and potential impacts in the study area. Depending on the availability of food, C. sapidus can adapt to a diverse resource utilization in the Guadalquivir estuary. The main consumed preys were fish, molluscs, and crabs, but they also consumed sediments and vegetation, although in smaller quantities and with a lower frequency. Diet composition was very generalist, and no seasonal or sexual effects were detected. However, diet seems to be more diverse in summer, while in winter blue crabs seem to switch trophic strategies to cannibalism or scavenging on fishing discarded nets. In addition, sexual dimorphism of chela and different spatial distribution seem to diverge the diet composition between males and females during the different sampled seasons. This requires the establishment of many diverse trophic interactions between the Atlantic blue crab and the native food web, which could lead to future impacts on the native community. Consequently, we believe that prey monitoring and control over this non-native species should be considered a priority for the management and conservation of the Guadalquivir estuary. Other methodological approaches as laboratory experiments and feeding habits predictors should be considered as future studies to better describe the trophic behaviour in the whole C. sapidus species.