Probabilistic models for studying the potential spatial distribution of three intertidal decapods in the north of Chile (Taltal, 25°S, Antofagasta region)

Abstract The northern Chilean coast is characterized by its high productivity and diversity due to the presence of the cold, nutrient-rich water of the Humboldt Current. The coasts in the area are mainly bordered by rocky shores that provide many microhabitats for invertebrates. The aim of the present study was to analyse the spatial distribution of three sympatric intertidal decapods, Leptograpsus variegatus, Cyclograpsus cinereus and Petrolisthes granulosus, using probabilistic models. The studied locality was situated on the rocky shores of Taltal Bay, in the north of Chile. The counting of individuals could reveal the presence of the reported species, and if they did or did not coexist. The results revealed that L. variegatus and C. cinereus had a uniform pattern with Binomial distribition, whereas P. granulosus showed a random occurrence with Poisson distribution. These results would not coincide with classical observations of intertidal decapods on the rocky shores of continental Chile, as those denoted a gregarious pattern, but the distributions found would rather explain potential territorial behaviour.