Abstract
Brazil faces a challenge to develop biomonitoring tools to be used in water quality assessment programs, but few multimetric indices were developed so far. This study is part of an effort to test and implement programs using benthic macroinvertebrates as bioindicators in Rio de Janeiro State. Our aim was first to test the Multimetric Index for Serra dos Órgãos (SOMI) for a different area--Serra da Bocaina (SB)--in the same ecoregion. We sampled 27 streams of different sizes and altitudes in the SB region. Despite the environmental similarities, results indicated biological differences between reference sites of the two regions. Considering these differences, we decided to develop an index specific for the SB region, the Serra da Bocaina Multimetric Index (MISB). We tested twenty-two metrics for sensitivity to impairment and redundancy, and six metrics were considered valid to integrate the MISB: Family Richness, Trichoptera Richness, % Coleoptera, % Diptera, IBE-IOC index, EPT / Chironomidae ratio. A test of the MISB in eleven sites indicated it was more related to land-use and water physico-chemical parameters than with altitude or stream width, being a useful tool for the monitoring and assessment of streams in the bioregion.
Highlights
The integrity of aquatic ecosystems can not be analyzed solely based on physical and chemical parameters of the water; it must consider the physical habitat structure, flow and channel modifications, biological alterations, and land-use in the watershed (Karr and Dudley, 1981)
Results showed sites of the two regions distinct biologically (Figure 2). This pattern may be a result of the higher richness of almost all macroinvertebrate orders found in Serra da Bocaina (SB) reference sites, totaling a mean of 74 taxa per site, while Serra dos Órgãos (SO) sites had a mean of 45 taxa per reference site (39-57 taxa)
If we only consider total richness of Ephemeroptera + Plecoptera + Trichoptera (EPT) genera found in the two bioregions (65; with 33 Trichoptera, 25 Ephemeroptera and 7 Plecoptera), SB had 64 genera occurring in this region, while only 42 genera were found in SO sampling sites
Summary
The integrity of aquatic ecosystems can not be analyzed solely based on physical and chemical parameters of the water; it must consider the physical habitat structure, flow and channel modifications, biological alterations, and land-use in the watershed (Karr and Dudley, 1981). In the 1980s, the multimetric system (Karr et al, 1986; Karr 1991) became popular, especially in the United States (Plafkin et al, 1989; Barbour et al, 1996; Barbour et al, 1999; Gibson et al, 1996; Blocksom, 2003). This bioassessment framework is based on the establishment of reference areas which are compared to impaired sites. Countries of the European Union, following the propositions defined by the European Community Water Framework Directive (EC 2000), adopted multimetric indices based on macroinvertebrates (Böhmer et al, 2004; Buffagni et al, 2004; Hering et al, 2004; Pinto et al, 2004; Vlek et al, 2004) as a primary tool to assess the ecological quality of waters
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