Importance of lentic waterbodies as fish nurseries in the flood plain of the Dyje River, Czech Republic

The occurence of 0+ juvenile fish was observed using a point abundance sampling strategy in non-flooded borrow pits, flooded borrow pits, oxbows and backwaters in the flood plain of the River Dyje in August 1998 and 1999. The season of 1998 was characterized by a shorttime managed flooding compared to a long-time managed flooding in 1999. Totally we registered the occurrence of 19 species of 0+ juvenile fish. The most abundant species were Scardinius erythrophthalmus, Perca fluviatilis, Rhodeus sericeus, Rutilus rutilus, Blicca bjoerkna and Alburnus alburnus. In the two years the composition and abundance of 0+ fish communities differed, especially in flooded borrow pits. A significantly higher species richness was found in both years in backwaters and flooded borrow pits compared to species richness in borrow pits and oxbows. The highest Catch per unit effort (CPUE) of 0+ fish was in the flooded borrow pits while the lowest CPUE was in non-flooded borrow pits. The duration of borrow pit flooding affected 0+ recruitment. In 1998, after short-time flooding, survival of 0+ fish was affected by predation of P. fluviatilis and high infection of metacercariae of Postodiplostomum cuticola.