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Fish Assemblages in Pampean Streams (Buenos Aires, Argentina): Relationship to Abiotic and Anthropic Variables


The present study reported the effect of natural and anthropic environmentalvariables on the fi sh assemblages in the pampean streams, in the coastal strip along the Río de la Plata, Buenos Aires province, Argentina. Five streams were sampled at 12sites surrounded by land devoted to different uses. A correspondence analysis sorted the streams into two groups: a less impacted group formed by sites surrounded bylivestock- raising pastures and a more impacted one passing through urban sites and including a stream adjacent to a modest rural urbanization with a dairy in the stream’sbasin. The nutrient concentrations were signifi cantly higher in the more impacted group; with species richness, diversity, abundance, and biomass being signifi cantlylower. A canonical-correspondence analysis related the more impacted sites to high concentrations of soluble reactive phosphorus and impoverished fi sh assemblages,composed of species tolerant to environmental pollution. On the other hand, sites with higher oxygen concentrations and pH were related to richer assemblages pointing togood environmental conditions at the sites surrounded by livestock-raising pastures. The downstream sites on the less impacted streams contained fi sh assemblages inwhich the juvenile stages of species corresponding to the Río de la Plata were dominant.

Palabras clave
environmental variables
freshwater fish
land use
nutrient concentrations

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