Behavioural similarities in different species of sandhoppers inhabiting transient environments

Abstract On sandy shores, physical constraints are expected to be the main driving force in defining both presence and behaviour of different inhabiting species. We tested the orientation of sandhoppers found on Atlantic shores in Morocco, on two banks of an ephemeral river mouth, presenting different ecological characteristics. Replicates were carried out before and after summer, when a seasonal changing of both natural and human-driven environmental features is expected, due to increasing temperatures, dryness and tourist frequentation. These features were differently affecting the two wadi banks, supplying a natural set of environmental conditions to be tested. Three species were found at the site, with different distribution on the two banks: Talorchestia spinifera was found on both banks; Talorchestia brito on the left bank only and Talitrus saltator on the right bank only. Although samples decreased in abundance after summer, the multiple regression models developed from the orientation datasets and selected with the Akaike Information Criterion retained the same variables to explain the orientation of the individuals tested: an environmental (the river bank), an intrinsic (the sex) and an immediate (the time of the day) one. This highlighted a role of the environment, including human pressures, in shaping a) sandhopper’ species occurrence and b) a common behavioural strategy to cope with environmental changes, disregarding the species. Occurrence and behaviour of talitrids resulted thus partly independent one from another. These experiments also provided the first behavioural data for the species T. spinifera and its comparison with other supralittoral amphipod species.