Ballast Blog – Invader of the Week – Percnon Gibbesi Crab

Malin Group Ballast Blog

An astounding number of invasive species have established populations in the Mediterranean region, with an estimated introduction of one new species every four weeks for the past five years. This weeks article looks at the species regarded as being the most invasive decapod to enter the Mediterranean – the percnon gibbesi crab.

Native to the west and east coast of America and the east coast of the Atlantic, the species is a relatively new arrival to the Mediterranean, having first been found in Sicily in 1999. It has subsequently spread to Greece and Turkey. Transportation via ballast water is a possible vector responsible for the introduction.

This crab competes directly with the Mediterranean’s native grapsid crab – the pachygrapsus marmoratus – which is likely to damage the biodiversity in the region.

(Photograph courtesy of