Statistical analyses
Data analyses were conducted in R version 4.1.0 (R Core Team 2021) and R
Studio 1.4.1717. For the analyses of fish community composition, we
removed all fish species with an abundance ≤ 0.1% and we focused on the
remaining 15 species. We used the vegan package and conducted Analysis
of similarities (ANOSIM) on the Bray-Curtis dissimilarly measure (9999
permutations) to determine the significance of differences among
communities of benthic invertebrates and fish upstream and downstream of
the dam. We further used non-parametric Mann-Whitney U Tests to compare
the total abundance of benthic invertebrates, CPUE and BPUE of fish, and
condition factor of pike upstream and downstream of the dam. We used
Mann-Whitney U Tests to compare the number of terrestrial insects in the
gut, as well as the terrestrial index for the three most abundant fish
species (i.e. roach, bleak, perch) upstream and downstream of the dam.