The blue Atlantic crab, Callinectes sapidus is a decapod crustacean native to a vast stretch of the western Atlantic seaboard, from Maine to the Río de la Plata. In the Mediterranean the species was accidentally introduced in Greece in 1948 and since then its abundance has been gradually increased posing a threat to native fisheries, and the overall diversity.

This study conducted food-preference experiments to assess the effect of predator and prey sizes and prey type in predation patterns and its possible causes. Species tested as prey were: the commercial ones, Mediterranean mussel (Mytillus galloprovincialis) and Pacific oyster (Cressotrea gigas), and the invasive ones, apple snail (Pomacea maculata) and Asian clam (Corbicula fluminea).

The results show that, except for the Pacific oyster, which attains protection at sizes of 50-70 mm and was little consumed, the other preys are readily predated, at variable rates, depending on predator and prey sizes.

The authors stress the need of fishing blue crab in marine areas to prevent losses in mussel production and highlight the potential control exerted by the blue crab over undesired invasive mollusc species.

https://www.sciencedirect.com/science/article/abs/pii/S0272771420307289

Prado et al. (2020) Prey size species preferences in the invasive blue crab, Callinectes sapidus: Potential effects in marine and freshwater ecosystems. Estuarine, Coastal and Shelf Science 245:106997.