Impact of anthropogenic disturbances on beetle communities of French Mediterranean coastal dunes

In coastal dunes, influenced by anthropogenic activities such as tourism, it is important to determine the relative influence of environmental factors at different spatial scales to evaluate the sensitivity of local communities to disturbances. We analyzed beetle communities of 14 dunes of the French Mediterranean coast: four in the relatively preserved Camargue area, and ten in the Var department, where tourism is intensive. Beetle communities were studied three times in early spring using sand sampling. Species-environment relationships were evaluated at the regional, landscape and local scale using redundancy analysis (RDA) and variability partitioning. About 28 species were identified, of which 15 were sand-specialist species, which accounted for more than 93% of total abundance. The beetle communities of Camargue were significantly different from those of the Var department owing to the pullulation of a Tenebrionid species (Trachyscelis aphodioides Latr.) in the Var, except for one restored dune where the community was very similar to those of Camargue. Our results showed no longitudinal gradient between the two regions. Local factors (dune height, preservation and disturbance index) significantly explained most of the variation in the dominance of T. aphodioides, while some other local factors were important for other psammophilous species. This study also suggests that dune beetle communities are strongly affected on beaches intensively managed for tourism, but beetles are still abundant in much disturbed sites.