Distribution and habitat structure of Ocypode gaudichaudii H. Milne Edwards & Lucas, 1843, in sandy beaches of northern Chile

Ten sandy beaches along the coast of northern Chile (20-23 degreesS) were s tudied in December 1998, to examine the distribution, abundance, and habita t characteristics of the crab Ocypode gaudichaudii. Beach width. slope, and intertidal fringes were identified, and Dean's parameter, describing beach morphodynamic status, was calculated. Crabs were collected and burrows and physical characteristics of the burrow zones analysed. The burrow zone ext ended primarily across the dry and retention zones. Physical properties acr oss the burrow areas did not influence burrow characteristics. Significant differences in burrow density were detected both within and among the 10 sa ndy beaches. These differences were not related to morphodynamic beach type s, but could be explained by related aspects, such as the height of the dri ft line, and the width and slope of dry and retention zones. We linked thes e results to behavioural and not just to physical causes.