Benthic macroinvertebrates and heavy metals in the Pilcomayo River Tarija, Bolivia Macroinvertebrados bentonicos y metales pesados en el Rio Pilcomayo Tarija, Bolivia
Oller, C.; Goitia, E.
Revista Boliviana de Ecologia y Conservacion Ambiental 18: 17-32
2005
Document Number: 383955
Heavy metal impact on macroinvertebrate community structure was studied in the Pilcomayo River. Samples were obtained in six stations and three periods in the lower and medium part of the river (300 - 600 m). Physical and chemical parameters were determined as well as heavy metal concentration, DQO, oils, and fats. Data were analyzed by ANOVA and principal components analysis. Significant spatial and temporal differences in the biotic, physical, and chemical components were detected. During the dry season, Pb, Cu, Zn, and As concentrations exceed legal limits, but decreased significantly thereafter. Macroinvertebrates densities were high during the dry season and low during the rainy season. Macroinvetebrate richness was low. Highest richness was recorded for Ephemeroptera and Trichoptera. Differences in the macroinvertebrate community structure were mostly attributable to physical and chemical variables (mainly DO and substrate) rather than to heavy metal concentration.