Distribution of epigean Gammaridae (Crustacea, Amphipoda) in the Loire river and in the streams of the Region Centre (France)

This work shows the distribution of five Gammaridae species ( Echinogammarus berilloni, E. spinulicornis, Gammarus fossarum, G. p. pulex, G. roeseli) in the Region du Centre, an area including the Middle Loire Basin and the south of the Middle Seine Basin. About three hundred stations were sampled from 1980 to 1990. G. fossarum occurs only in the Allier river, G. p. pulex is the most common species, most often sympatric with E. berilloni, E. spinulicornis and G. roeseli are two species which have been spreading recently in this region. E. spinulicornis occurs mainly in the western part and only in the Loire basin, whereas G. roeseli occurs mainly in the eastern part both in the Seine and in the Loire basins.