Ichthyofauna of two streams in the high basin of the Samborombón River, Buenos Aires province, Argentina

Abstract

The ichthyofauna of the Manantiales (35°02’34”S; 58°19’37”W) and El Portugues (35°04’16”S; 58°26’09”W) streams, both of them pertaining to the high basin of the Samborombon River, in the Province of Buenos Aires, Argentina, was studied. Abundance, specific richness, diversity and temporary distribution were considered throughout an annual cycle. The specific diversity between both streams was compared and the physical and chemical parameters of the environment analizad. In total 8595 specimens were captured, pertaining to 20 species, 11 families and 5 orders. The order Characiformes was the most widely represented with 10 species and a relative abundance of 50%, followed by the order Siluriformes with 6 species and a relative abundance of 30%. The specific richness in the Manantiales was of 20 species, the annual diversity index was 1.42 and the uniformity index was 0.58. The specific richness in El Portugues was of 17 species, the annual diversity index was 1.51 and the uniformity index was 0.64. Differences in the composition of dominant species were observed. The diversity values are similar to that recorded in Pampasia and southern Brazil streams.