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In an attempt to unravel the possible relationships among coastal stability, genetic variability and orientation behaviour in the sandhopper Talitrus saltator, we have screened four subpopulations of this species. Sandhoppers along 3 km of a dynamic sand beach were studied for orientation performance (i.e. adherence to the seaward theoretical escape direction (TED)) and sequence variation for a fragment of the mitochondrial (mt) gene encoding for the cytochrome oxidase subunit I (COI). The sampling sites differed in the stability of the shoreline (from severely eroded to accreting). Analysis of molecular variance (AMOVA) revealed significant subdivisions among the four locations. The subpopulation sampled at the most eroded point showed no haplotype diversity and had the highest scatter in orientation. Genetic diversity increased with decreasing erosion. Orientation performances were best where the beach is in dynamic equilibrium, and were progressively more scattered at the accreting points. Multiple linear regression analyses demonstrated that the variables and factors that affected orientation significantly were daytime, global solar radiation, sex of individuals and haplotype diversity. Environmental factors are likely to influence sandhopper behaviour on a short and medium time scale (i.e. from single individual life span to a few generations). The data also suggest that temporal stability of the shoreline has a positive effect on the genetic variability of the resident sandhopper populations. [ABSTRACT FROM AUTHOR]

Sandhoppers orient towards the shoreline using a sun compass when they are subject to dry conditions. In this study we analysed the orientation of populations from two sandy beaches with wide tidal excursions (Brittany, France): at Damgan (sea to the South) and at Le Verger (sea to the North). At Le Verger beach Talitrus saltator was found together with Deshayesorchestia deshayesii (former Talorchestia deshayesii). The results of the experiments on sun and landscape orientation showed that the Damgan T. saltator oriented better with ebbing tides than with rising tides, while the Le Verger T. saltator showed the opposite trend as a response to tides. This is probably related to the differing risk of being swept away by tides at the two localities. D. deshayesii was found to be more scattered in orientation than T. saltator, probably because it is a recent colonizer of that beach. [ABSTRACT FROM AUTHOR]

Examines the timing, orientation and motivating and directing factors of the spontaneous movements of the sandhopper Talitrus saltator on a Mediterranean beach in Tuscany, Italy. Landward migration after sunset for juveniles; Effect of temperature on spontaneous movements; Description of the habitat of the sandhopper, Talitrus saltator.