INFLUENCE OF FLOODS ON FISH COMMUNITY IN TWO LOTIC HABITATS (CIRCULAR MEANDER POOL AND CONFLUENCE SCOUR HOLE) IN THE MIDDLE PARANÁ RIVER FLOODPLAIN.

RABUFFETTI ANA PIA; ELIE ABRIAL; ALDO RAUL PAIRA; ESPÍNOLA LUIS ALBERTO; AMSLER MARIO LUIS

Santa Fe

Congreso; 5º. CONGRESO ARGENTINO DE LIMNOLOGÍA (CAL5); 2012

Instituto Nacional de Limnología (INALI ? CONICET ? UNL) Facultad de Humanidades y Ciencias. Universidad Nacional del Litoral (UNL)

Spatial and temporal variations in species richness and abundance indicated by the capture per effort unit (CPUE) of fish into a circular meander pool and a confluence scour hole located in the floodplain of the Middle Paraná River were analyzed from 2009 to 2012 during floods and dry periods. Annual variations of the water level were known on the base of hydrometric levels recorded at the Santa Fe city gauge (data supplied by the Dirección Nacional de Vías Navegables, Argentina). Canonical analysis on the principal coordinates based on any symmetric distance matrix was applied to determine eventual significant differences on spatial and temporal distribution of fish community in both habitat. Analyses of variance enabled to study relationships of three groups of species (sedentary, short and long-distance migratory fish) with the hydrologic regime. No significant difference were found between the fish community in the circular meander pool and the confluence scour hole but significant variations occur at different stages of the hydrologic regime. Species richness and abundance of long-distance migrants are closely related to the duration, intensity and timing of the flood phases whereas short-distance migratory fish show a lower dependence on the flood conditions and seems to have different responses according to the kind of species. Sedentary fishes are equally influenced by floods but are more regular in species occurrence and abundance than migratory fishes at the end of the flood phase in the floodplain.