Distribution patterns of the ghost crab Ocypode cursor on sandy beaches of a tropical island in the Cabo Verde archipelago, Eastern Central Atlantic

Abstract

The spatial distribution of the ghost crab Ocypode cursor was determined for beaches on eastern Boa Vista Island, Cabo Verde Archipelago. The main objectives were to analyse the across-shore distribution by means of burrow counts and to identify preferential zones and spatial segregation. Six beaches were investigated using 20 acrossshore beach transects. It was demonstrated that ghost crabs occur throughout the entire intertidal zone, with higher densities in a 9–13 m band above the waterline. There was an exponential relationship between the carapace length of captured crabs and the diameter of their burrows. Mean burrow diameter was correlated with burrow density and increased linearly with distance from the waterline, although small burrows, representing individuals smaller than the median size, occurred across the beach. Burrow diameter and depth were positively correlated, with larger holes indicating larger crabs and deeper burrows. Deeper burrows were more common in the upper intertidal zone. These results are similar to those described for ghost crab populations elsewhere and contribute to an understanding of the ecology of the species in the local context.

Keywords: burrows, crustacean, density, intertidal distribution, population structure