Ichthyofauna of the Cuyuni basin in Venezuela

This paper presents preliminary information on the fish of the Cuyuni River basin in Venezuela and on the impacts produced by anthropogenic and mining activities on the fish community of several areas along a transect on the river. Some environmental characteristics indicative of environmental quali ty in areas subjected to various levels of human impact, and the correspond ing number of specimens, species, and indices of diversity and evenness wer e determined. A total of 136 species in 29 families are reported The most d iverse families were Characidae, Loricariidae, Cichlidae and Pimelodidae. O ther families were comprised of 10% or less of the total number of species reported. The environmental attributes of the different areas sampled, conf orm to a pattern where areas of clear water, low suspended sediments and hi gh vegetation coverage, represented by the Kinotovaca Rapids (Station I) an d Station II, at the extremes of the transect, had the most diversify of fi sh species: 87 and 51 species, respectively. Those areas where the water pr esented moderate to high sediment loads, had scarce vegetation cover and re latively high temperatures, presented moderate values of the indices of div ersity and evenness, with species numbers ranging from 42 to 19. Station 12 , at the mouth of Quebrada Amarilla, a creek that drains extensive areas of mining activities, was devoid of fish. Areas upstream of the mouth of this creek on the Cuyuni River had in general more species (21 to 17) than area s downstream (14 to 16), an indication of the negative impact produced by i ts discharge on the Cuyuni River. Samples taken 20 years apart in areas whi ch have been subjected to low environmental impacts were comparable in term s of their diversity of fish species. In those areas, several species of hi gh scenic value and/or economic importance were still common. Areas close t o settlements, villages or sites of mining activities presented low diversi ty indices, indicative of low environmental quality. Given these results, i t is imperative that in as short a period as possible, a plan be conducted to recuperate, conserve, and manage the impacted areas which not only harbo r a high diversity of animal and plant species, but also have a high scenic , cultural and economic value.