Walkways as an environmental enrichment tool on sandy beaches? A case study with ghost crabs (Crustacea, Ocypodidae)

Confined to a few favorable patches of habitat within a mosaic of physical drivers, many species disappear from human-disturbed beaches. However, mobile species may change their distribution and select more appropriate habitats as a response to disturbance. Ghost crabs are one of the few beach resident animals capable of moving over considerable distances, but usual habitat homogeneity of urban beaches theoretically prevents them from finding refuge. Here, I tested whether access walkways provide a habitat for ghost crabs on four beaches in southeastern Brazil. I counted and measured burrow opening diameter under walkways and in surrounding transects located at various distances from these structures between June 2020 and May 2021. Mean burrow density was three times higher in transects out of walkways than under the walkways. However, burrows were larger and positioned farther from the waterline under walkways. Walkways thus possibly provide protection for ghost crabs from trampling and vehicle traffic in urban beaches and could therefore be applied as an environmental enrichment tool in the management and conservation of sandy beach biodiversity.