Canonical Correspondence Analysis (CCA): biplot of the environmental matrix showing environmental variables (grey arrows) and of the fish matrix with densities and standing crop of the brown trout, and densities, standing crop, Kn of the bullhead (black triangles). The first two ordination axes explained 93.30% of the total variance. Eigenvalues of axis 1 and 2 were 0.082 and 0.027, respectively. The length of each arrow is proportional to the rate of change and indicates the strength of the correlation with the axes.