3.1 Habitat conditions
The first and second axes of PCA explained 28.98% and 19.18% of the
habitat variances, respectively.
Impoundments had higher water width, water depth, and lower current
velocity and substrate coarseness than free-flowing segments (Figure 3).
PERMANOVA showed that habitat conditions significantly differed between
the impoundments and free-flowing segments
(R2 =0.13, P <0.001). However,
PERMDISP showed that habitat heterogeneity (i.e., average distance to
median) did not significantly differ between the two habitat types
(ANOVA like permutation F =0.89, P >0.05) and
that of the impoundments (2.31 ± 1.09 [mean ± standard deviation])
was slightly higher than that of the free-flowing segments (2.11 ± 1.08
[mean ± standard deviation]).