Tuesday, May 27, 2008 - 9:15 AM
126

Use of the "BEAST" model for biomonitoring water quality in a neotropical watershed

Pablo Moreno and Marcos Callisto. Biologia Geral, Universidade Federal de Minas Gerais, Av Antonio Carlos, 6627, Pampulha, CP. 31.270-901, Belo Horizonte, Brazil

Bioassessment tools that relate macroinvertebrate assemblage characteristics to the resource quality of freshwaters and other systems usually use the "reference condition approach" (RCA) that compares stressed sites with a group of minimally disturbed reference sites. The BEAST predictive model (BEnthic Assessment of SedimenT) was used to test whether a new site falls within the given confidence limits of a specified MDS-ordination space, defined based on the probability of site membership within the reference-site group. Our hypothesis was that a gradient of environmental degradation determines the composition and structure of benthic assemblages in the Rio das Velhas watershed of southeastern Brazil. In total, 362,904 invertebrates were collected from 37 river sites during rainy and dry seasons from August/04 to May/06, including 14 sites in minimally disturbed condition. The BEAST results classified 16 unknown ecological condition sites as (i) natural (2 sites, 7 typical benthic families), (ii) altered (4 sites, 12 typical tolerant benthic families), (iii) impacted (3 sites, 2 resistant families), and (iv) degraded (7 sites, 5 resistant families). The predictive model approach associated with biological indices offered many advantages for assessing water quality in the das Velhas watershed, supporting their use by environmental managers.


Web Page: environmental impact, benthic macroinvertebrates, reference condition, Brazilian watershed

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