Observations on the alien crab Percnon gibbesi (Decapoda, Brachyura, Grapsidae) from the Maltese Islands

Abstract

A preliminary account on habitat preferences, bathymetric distribution, population density, and aspects of the reproductive biology of the alien grapsid Percnon gibbesi in the Maltese Islands is given. This alien was first recorded from Malta in 2001 and has since established breeding populations in suitable habitats throughout the Maltese islands where of its preferred habitat types, upper infralittoral boulder fields or rock faces with a sparse algal cover, are available. The crab breeds in summer and recruits in winter. Female crabs may produce up to 30,000 eggs per spawning. Interactions with the native grapsid Pachygrapsus marmoratus were observed.