Biomonitoring of benthic macroinvertebrates in the middle Doce River watershed.
MORETTI1,2, M. S. & CALLISTO1, M.
1 UFMG / Instituto de Ciências Biológicas, Depto. Biologia Geral, Lab. Ecologia de Bentos
Av. Antônio Carlos 6627, C.P. 486, CEP 30.161-970, Belo Horizonte, MG, Brasil. callisto@icb.ufmg.br
2 Programa de Pós-graduação em Ecologia, Conservação e Manejo da Vida Silvestre,UFMG.
ABSTRACT: The aim of this study was to assess the benthic macroinvertebrate communities in seven lotic and four lentic ecosystems in the middle Doce River watershed (MG, Brazil) during the rainy and dry periods of 2000-2001. A total of 110 sediment samples were collected in the lakes, and 153 in the rivers. Sediment organic matter contents and granulometric composition analysis were also done. Shannon-Wiener diversity and Pielou evenness indices were calculated and the U-test of Mann-Whitney was used to evaluate whether there were differences on density (ind.m-2) and taxonomic richness values between the studied periods. In the rivers, sediment granulometric composition presented a mixture of particles and fractions. Lake sediments were organic and showed high percentages of silt and clay. A total of 49 taxa was found in lotic ecosystems and the highest density was found in 2001 (> 30,000 ind.m-2). The lowest values of taxa richness were found in Piracicaba and Ipanema Rivers (6 and 2 taxa, respectively). Total density of macroinvertebrates was different between rainy and dry seasons in 2001 (p < 0.005). Evenness index values were high and diversity values were low (H’ < 0.7). In the lakes, 31 invertebrate taxa were found and the highest density was found in the dry period of 2001 (2,500 ind.m-2). Carioca Lake showed high density and taxa richness in all sampling periods (> 750 ind.m-2 and > 6 taxa). Significant differences were found on densities and on taxa richness between rainy and dry seasons in 2000 and 2001 (p < 0.005). Thus, benthic macroinvertebrate communities can be used as a tool in the assessment of water quality and freshwater ecosystem health.
Key-words: benthic macroinvertebrates, water quality bioindicators, family-level identification, Doce River watershed.