Indice multimétrico de integridad biótica béntica para la cuenca del Río Chipiriri, Cochabamba - Bolivia

Abstract

MULTIMETRIC INDEX OF BIOTIC INTEGRITY BASED ON MACROINVERTEBRATES TO ASSESS BIOTIC CONDITION OF STREAMS IN THE CHIPIRIRI BASIN, COCHABAMBA - BOLIVIA Con el proposito de desarrollar un indice multimetrico para evaluar la calidad biologica de los rios de la Cuenca Chipiriri (Bolivia), tomamos muestras de macroinvertebrados bentonicos y medidas ambientales en dos grupos de sitios distribuidos uniformemente en toda la cuenca, 38 sitios con minima perturbacion antropogenica y 29 sitios perturbados. Usando los datos del primer grupo de sitios, desarrollamos modelos estadisticos sencillos de modo que expliquen adecuadamente los patrones observados de 12 diferentes variables biologicas tomadas en cuenta; posteriormente, seleccionamos las variables biologicas mas efectivas que respondieron de forma significativa a efectos de perturbacion. Finalmente, sumando los valores de las variables biologicas seleccionadas obtuvimos el indice final que distinguio claramente la variacion de la calidad biologica de las condiciones naturales y perturbadas. Los metodos y consideraciones descritas en este trabajo, podrian emplearse para desarrollar un indice de integridad ecologica en otras regiones, incluyendo nuevos parametros a esta escala. Palabras claves: Evaluacion biologica, macroinvertebrados, rios tropicales, perturbacion antropogenica, Chapare, Bolivia. ABSTRACT In order to develop a multimetric biotic integrity index, we collected data on the macroinvertebrate communities and local environmental habitat descriptors in 38 reference and 29 disturbed sites, uniformly distribute within the Chipiriri watershed (Bolivia). Using the reference data set, stepwise multiple linear regression procedures were first applied to develop the simplest possible response model that adequately explained the observed patterns of 12 different biological variables, reflecting macroinvertebrate community structure. In a second step, we selected the most effective variables that discriminate between reference and disturbed sites. Finally, adding the values of the biological variables selected, we obtained a final index score that described biotic integrity of the reference and disturbed sites as excellent, good, fair, poor, or very poor. Our final index achieved good distinction between natural and human-induced variation in biological condition. Including additional parameters, this approach could be used in the near future to develop a nation biotic integrity index. Key words: Bioassessment, macroinvertebrates, tropical streams, anthropogenic disturbance, Chapare, Bolivia.