Abstract
The objective of this study was to develop a rapid multimetric index using benthic macrofauna as bioindicators of ecological conditions for the upper reaches of the Piabanha-Paquequer-Preto Basin located in the state of Rio de Janeiro, Brazil. A total of 33698 macroinvertebrates were collected in 27 sites. Benthic macroinvertebrates were sampled using the multi-habitat method that consists in sampling 20 m2 of substrate collected in approximate proportion to the representation of all major habitat types in the reach. A subsampling procedure was used. The main steps followed to develop and test the index were: exclusion of unsuitable metrics using box-whisker plots, considering the degree of overlapping among interquartile limits (1o-3o) and confirmed by Mann-Whitney U test (p < 0.05) using six reference rivers and six impaired rivers. From all the candidate potential metrics, 36 were considered suitable. After identifying redundant metrics, through Spearman correlation analysis, and considering practical application criteria, six core metrics were selected to compose the Piabanha-Paquequer-Preto Multimetric Index (PPPMI) using the continuous method: Family richness, Shannon-Wiener family diversity, EPT family richness, %Diptera, %MOLD (Mollusca + Diptera) and %Collectors. The sensitivity of the index was tested in 15 rivers using a Principal Components Analysis (PCA) of the six environmental variables. The first axis of the PCA was highly correlated to the PPPMI scores (r = 0.703, p < 0.001). The PPPMI responded to a set of environmental variables associated to a gradient of human disturbance affecting the ecological condition of the waterbodies. This indicates that the PPPMI is an effective tool for biological monitoring and decision making in the hydrographic region of the Piabanha-Paquequer-Preto rivers.
Highlights
Beginning in the 1970’s, several countries around the world began to defend a policy which stated that the primary objective of surface water assessments should be to understand their ecological condition
The review of the first national assessment of stream ecosystems in the USA presented by PAULSEN et al (2008) indicates that it is feasable to use multimetric indexes in large scale monitoring programs in order to assess the ecological condition of rivers
Its headwaters are located in the Serra dos Órgãos region, within the central portion of the Serra do Mar in the state of Rio de Janeiro
Summary
Beginning in the 1970’s, several countries around the world began to defend a policy which stated that the primary objective of surface water assessments should be to understand their ecological condition. KARR & DUDLEY (1981) argue that biotic integrity represents “The ability to support and maintain a balanced, integrated adaptive assemblage of organisms having species composition, diversity, and functional organization comparable of that of natural habitat of the region” Several developed countries, such as United States of America, Canada, Australia and New Zealand have invested on the development of models and biological indicators (PLAFKIN et al 1989, WRIGHT 1995, REYNOLDSON et al 1995, BARBOUR et al 1996, 1999, BONADA et al 2006). The review of the first national assessment of stream ecosystems in the USA presented by PAULSEN et al (2008) indicates that it is feasable to use multimetric indexes in large scale monitoring programs in order to assess the ecological condition of rivers
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