| 24 Species of Gastropoda, representing 3357 specimens, have been sampled in 57 varied ponds of Brittany (France). The most frequent species (at least in 10% of the samples) are considered according to their average abundance and dominance. The average specific richness of the ponds where the species have been collected is studied. In a second stage, the Gastropoda are analysed by means of a principal component analysis. The 1-2 plane correspond to 87% of the whole variance. This analysis associated with a cluster analysis led to the partition of 5 groups of species. |
