Use of Benthic macroinvertebrate to assess the biological status of pampean streams in Argentina.

RODRIGUES CAPÍTULO A; TANGORRA, M,; OCON C

AQUATIC ECOLOGY

SPRINGER

Lugar: Netherlands; Año: 2001 vol. 35 p. 109 - 119

1386-2588

Abstract Macro-invertebrate communities and environmental variables were assessed seasonally for two years in seven streams in  North- Eastern of Buenos Aires province (Argentina) in order  to analyse changes in their  structure and composition in relation with the quality  of the water. The study includes pristine streams and others affected  by urban and industrial effluents with high conductivity, nitrates, nitrites, phosphates  and low oxygen content. Organisms with well-known pollution tolerance were identified to assess biological water quality, using a new Biotic Index (IBPAMP: Biotic Index for Pampean rivers and streams) in comparison with other existing biotic indices. The usefulness of principal component analysis (PCA) and correlation matrices were examined to evaluate the efficiency of the method to assess disturbances. In general IBPAMP did well correlate with several classical measures of biological water quality (taxon richness, diversity and several biotic indices).  The El Gato stream was the most disturbed ecosystem among all studied sites. It was characterised  by low dissolved oxygen levels, high turbidity in the middle course,  high BOD5 (>30 mg l-1) and COD (> 40 mg l-1)  values. The Buñirigo stream has a bad quality in the industrial area, but varying according to the dry and wet periods. In general, in the mountainous areas the water quality of streams was good with the exception of the stations located downstream of cities like Ayacucho on the Tandileofú stream.