| Summary: | Topmouth gudgeon, Pseudorasbora parva is the most common invasive fish
in Europe, which can compete with the juveniles of valuable commercial fishes. The goal of
this work is to study the diet of topmouth gudgeon and trophic relationships with some
native fishes inhabiting the littoral zone of the Dniprodzerzhynsk reservoir. The obtained
relatively low values of diet overlaps between topmouth gudgeon and other co-occurring
cyprinids such as juvenile roach, Rutilus rutilus; silver bream,
Blicca bjoerkna; rudd, Scardinius erythrophthalmus;
Prussian carp, Carassius gibelio and bleak, Abramis
brama, indicate that it is not a serious food competitor for them, especially
commercially valuable ones. On the contrary, high diet overlaps were observed among some
native cyprinids such as juvenile roach, silver bream, rudd, and bleak. The major prey
items of topmouth gudgeon were Chydorus sphaericus and chironomids,
whereas other cyprinids selected Bosmina spp. This peculiarity may be due
to different vertical distributions of these fish in the littoral zone of the reservoir,
where topmouth gudgeon inhabit near-bottom water layers, where they preyed on near-bottom
and benthic zooplankters and chironomids, while juvenile roach, silver bream, rudd, and
juvenile and adult bleak live in higher water layers, where they preyed on pelagic
zooplankton.
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