Metabarcoding
Unfortunately, some problems during the PCR-procedure in the lab appeared that resulted in less fish individuals with a sequenced gut content. We identified 32 aquatic and 17 terrestrial species in the gut content of the 31 fish individuals analyzed (Appendix 1). Fish individuals feed on 1-8 different species and perch, irrespective of the location, had the most diverse diet (5 ± 3 species), in contrast to roach (3 ± 2 species), and bleak (2 ± 1 species) (Table 2). No terrestrial species were identified in the gut content of fish caught downstream of the dam and no terrestrial species were identified in the gut content of roach upstream of the dam either, thus, not allowing any statistical comparison (Table 2). However, in locations upstream the dam, terrestrial species were ingested by bleak (1 species ± 1) and perch (4 species ± 1) and this result was significant for the latter species (Z = 6.137, P = 0.013, Table 2).