Macroinvertebrate and fish community
While Chironomidae were the most abundant taxa in the invertebrates samples of sites located upstream of the dam, Bivalvia and Gastropoda dominated the community composition upstream of the dam (Appendix 1). However, ANOSIM revealed that the composition of community structure of benthic invertebrates upstream and downstream of the dam was not significantly different. Total abundance was significantly higher at locations downstream of the dam (Z = 3.86, P = 0.0495; 5945 individuals m-2 ± 2106, mean ± SD) compared to locations upstream of the dam (982 individuals m-2 ± 1100; Figure 2).
We caught 20 fish species in total (Appendix 2). The three most abundant fish species were roach Rutilus rutilus , bleak, and perch (37.6 %, 17.5 %, and 15.7 % of total abundance, respectively; Appendix 2). ANOSIM indicated that the fish community composition upstream and downstream of the dam was not significantly different, neither when accounting abundances (i.e., CPUE), nor biomass data (i.e., BPUE). However, total CPUE of all fishes was significantly higher in locations downstream of the dam (Z = 3.86, P = 0.0495; 158 individuals 1000 m-1 ± 49) compared to locations upstream of the dam (60 individuals 1000 m-1 ± 35; Figure 3), but BPUE was not significantly higher.