Temporal and spatial distribution of the ichthyofauna in two streams of the upper Rio Parana basin

The temporal and spatial distribution of the ichthyofauna was assessed in two streams, Caracu and Sao Pedro, affluents of the Rio Parana, from March 1991 through February 1992. Samples were taken along the streams, using sieves (three sites on the Caracu and two on the Sao Pedro), and gill nets (two sites on the Sao Pedro). A total of 6,664 specimens belonging to 71 species were captured. CPE was calculated for each fishing gear. The data for cumulative frequency indicated that only the mouths of streams did not reach an asymptote. Constancy analysis showed that occasional and accessory species predominated. The spectrum of spatial diversity indicated that diversity increased toward the mouth of streams and temporal diversity increased in the high water season. The results of correspondence analysis for sieved fishes and Sorensen similarity for netted ones showed that the sites located at the same position on the streams were more similar than between adjacent sites in the same stream.