Distribution Pattern of Macrophytic Community and Water Quality Indicators in Walloon Rivers

The objectives of this study were to describe the distribution of macrophyte assemblages in relation to
physico‐chemical parameters of their environment and to assess the variability in ecological metrics
throughout the Walloon river network. Two-way clustering allowed us to simultaneously assign sample
units and species to groups by performing two separate cluster analyses. Indicator species analysis
allowed us to assess the degree to which a species indicated a group, based on its constancy and
distribution of abundance. Hygroamblystegium fluviatile, Chiloscyphus polyanthos and Lemanea
fluviatilis were found to characterize acidic and low impacted streams and rivers (G1), while
Ranunculus fluitans was found in all low impacted large streams (G2). Potamogeton pectinatus,
proved to be more common in eutrophicated waters in the calcareous areas particularly in the ʺLoess
low plateauxʺ region (G6). Cinclidotus riparius, Fissidens crassipes and Pellia endiviifolia, appeared in
rivers situated in the Condroz region (G4), which was characterized by a high concentration of
nitrogen.