Spìvak et al. 1 Running title: Population structure and reproduction of Xantho poressa Population structure and reproductive biology of the stone crab Xantho poressa (Crustacea: Decapoda: Xanthidae) in the “Corrales de Rota” (SW Spain), a human-modified intertidal fishing area

The present study describes the reproductive biology, population structure and life history traits of the abundant intertidal crab Xantho poressa. Between March 2007 and April 2008, a total of 1918 individuals were collected in Corrales de Rota (SW Spain), a human-modified intertidal habitat characterized by an artificial high complexity. Suitable refuges for crabs (cobbles and boulders) are very abundant in this area and density (maximum of 50 ind*m -2 ) was directly related with the area covered by these stones. In spring and summer, size frequency distributions showed a polymodal pattern with seasonal variations related to the incorporation of juveniles to the adult population. Newly settled juveniles were not found in the corrales suggesting an