This study describes the application of a protocol for biological assessment of water quality at first to third order streams at Serra dos Ó rgã os, an area covered by Atlantic Forest in Rio de Janeiro State, Brazil. Major impacts in the region are domestic effluents and deforestation. Our main objective is to establish biocriteria for the establishment of the Serra dos Ó rgã os Multimetric Index (SOMI) based on benthic macroinvertebrates. We used data from previous studies, sampled by experienced biologists, from 1999 through 2002. The benthic macroinvertebrate community was sampled in 12 reference sites and seven impaired sites in three river basins: Guapimirim, Macaé and Grande, all from the same bioregion. From the 22 tested metrics, 6 were included in the SOMI (% Diptera, % Coleoptera, Family Taxa, EPT Taxa, BMWP-CETEC and % Shredders). Scores (5, 3 or 1) were developed for these metrics to allow for aggregation into the index. Seven intermediately impaired sites were used for evaluating the applicability of the multimetric index. We concluded that the SOMI is a robust easy-to-apply tool for biomonitoring programs in the Serra dos Ó rgã os region, south-east Brazil.

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Biomonitoring is defined as the systematic use of biological responses to assess environmental changes, usually anthropogenic impacts. In this article we present the conceptual basis and a brief history of biomonitoring as an assessment tool for environmental health. Considering the drawbacks of physical and chemical parameters to assess environmental quality, we pinpoint the need to integrate these analyses with information provided by biological monitoring. The application of biomonitoring in Brazil would help watershed managers and policy-makers to reduce costs, increase the efficiency of analyses, and simplify the results, allowing community participation through volunteer monitoring programs.

Diversity and habitat preference of macroinvertebrates were studied in Macaé River basin, Rio de Janeiro State, Brazil, along its longitudinal gradient. We selected stream reaches corresponding to 1 st , 2 nd , 4 th , 5 th and 6 th orders. A Surber sampler was used to collect four macroinvertebrates samples of each substrate (sand, litter in pool areas, stones, and litter in riffle areas) during the three sampling periods, defined based on the rain regime: April (end of the rainy season), July (dry season), and October (beginning of the rainy season). We identified 46,431 specimens corresponding to 117 taxa. Analysis of diversity numbers (both for family or genus level) indicated that all insect taxonomic orders had higher numbers on 2 nd order stream reach, except for Ephemeroptera, on 4 th order. However when considering morphspecies taxonomic level, the higher diversity number occurred on 4 th order stream. The highest richness and diversity numbers were found at the dry season. Considering habitat preference, both litter in pool areas and litter in riffle areas had the highest faunal richness.Key words: diversity, aquatic insects, longitudinal gradient, tropical river, Brazil. RESUMO

The objective of this article is to present an analysis of the main bioindicators that are currently used to assess the environmental impact of pollution in water resources. The simple quantification of chemicals in the environment is not enough to reveal the real effects of contamination on ecosystems, making necessary the assessment of the biological effects that pollution causes at different hierarchical levels. The bioindicators used in this article on two case studies comprehend different hierarchical levels: in case study 1, three organization levels were utilized: individual, cellular and molecular, to detect the early effects of exposition to environmental pollutants in three hydrographic basins. By observing the inhibition of AChE activity in fish it was possible to assess the effects of organophosphorate and carbamate pesticides, showing the effects of agricultural activities. In case study 2, we present an assessment at the macroinvertebrate community level using the Extended Biotic Index. We discuss the advantages and limitations in the production of reliable data that could be used in the implementation of adequate actions to protect and/or recover ecosystems.

Benthic macroinvertebrate assemblages are structured according to physical and chemical parameters that define microhabitats, including food supply, shelter to escape predators, and other biological parameters that influence reproductive success. the aim of this study is to investigate spatial and temporal distribution of macroinvertebrate assemblages at the macaé river basin, in rio de Janeiro state, Southeastern Brazil. according to the "habitat assessment field data Sheet -high Gradient Streams" (Barbour et al., 1999), the five sampling sites are considered as a reference condition. despite the differences in hydrological parameters (mean width, depth and discharge) among sites, the physicochemical parameters and functional feeding groups´ general structure were similar, except for the less impacted area, which showed more shredders. according to the detrended correspondence analysis based on substrates, there is a clear distinction between pool and riffle assemblages. in fact, the riffle litter substrate had higher taxa in terms of richness and abundance, but the pool litter substrate had the greatest number of exclusive taxa. a cluster analysis based on sampling sites data showed that temporal variation was the main factor in structuring macroinvertebrate assemblages in the studied habitats.Keywords: benthic macroinvertebrates, Southeastern Brazil, substrates, distribution. RESUMODistribuição espaço-temporal de macroinvertebrados bentônicos em um rio do sudeste brasileiro a fauna de macroinvertebrados bentônicos é estruturada por fatores físicos e químicos que determinam os microhábitats, incluindo a disponibilidade de alimento, a existência de refúgios contra predadores e tempestades, o sucesso reprodutivo e outros parâmetros biológicos. o objetivo deste estudo foi investigar a distribuição espaço-temporal da comunidade de macroinvertebrados bentônicos na bacia do rio macaé, estado do rio de Janeiro, Brasil. de acordo com o Habitat Assessment Field Data Sheet -High Gradient Streams (Barbour et al., 1999), os cinco locais coletados são considerados como referência para propósito de biomonitoramento. apesar das diferenças em parâmetros hidrográficos (largura, profundidade e vazão médias), os parâmetros físico-químicos e a composição dos grupos de alimentação funcional foram similares entre os locais, com exceção da área mais preservada, onde a porcentagem de organismos cortadores foi maior. de acordo com a análise de correspondência, há uma clara distinção entre áreas de remanso e de correnteza. de fato, o substrato folhiço de correnteza apresentou a fauna mais rica e abundante, enquanto o substrato folhiço de fundo apresentou o maior número de táxons exclusivos. a análise de agrupamento 624 Silveira, m. p. et al.

The distribution and abundance of aquatic insects were studied in the longitudinal gradient of the watershed of Macaé River, a coastal Atlantic Forest river in South-eastern Brazil. Sampling stations were selected in the first, second, fourth, fifth, and sixth orders and sampled in April, July, and October 1995. This represented the end of the rainy season, the dry season, and the beginning of another rainy season, respectively. In each month four samples were collected using a Surber sampler from each of the following substrates: sand, litter deposited in pool areas, litter in riffle areas, and stones. A total of 46,431 specimens of aquatic insects belonging to ten orders were obtained. The data were analyzed by the multivariate methodologies of Correspondence Analysis (CA) and Cluster Analysis (UPGMA) using the similarity index of Morisita, for all three months. Both showed a significant faunal disrupture in the river, which can be divided in two sections: the upper one, from first to fourth orders, and the lower section, including fifth and sixth orders. The same results were obtained with presence-absence matrices, using Jaccard similarity index, showing that the changes are not only due to quantitative differences. A Mantel test was used to compare the assemblage composition temporally and no difference was detected between the three months. Moreover, a Canonical Correspondence Analysis (CCA) was applied to the data to check which of the 14 physical and chemical variables significantly explained macroinvertebrate community variation. The most significant variables were conductivity, CPOM, and pH for the upper stations (1 st , 2 nd and 4 th orders), and alkalinity, FPOM, and HCO 3 for the lower stations (5 th and 6 th orders).

The River Continuum Concept (RCC) assumes that autochthonous primary production in forest streams is limited by light and is insufficient to sustain secondary production by consumers; they must therefore depend on allochthonous carbon from the surrounding forest. Recent studies have, however, questioned the importance of allochthonous carbon in stream food webs. There is a growing body of evidence using stable‐isotope techniques that demonstrate the importance of algae (autochthonous production) in the food webs of tropical streams. The actual contributions of autochthonous and allochthonous resources are rarely evaluated accurately because few studies consider the diet and the trophic efficiencies of the components of the food web or measure primary and secondary production to estimate the energy flow. We estimated the annual net primary productivity of periphytic microalgae (NPP) and the secondary production of macroinvertebrates (SP) from empirical models and we used stable isotopes of carbon and nitrogen to quantify the flow of material in food webs of five forest streams in the Guapi‐Macacu catchment, Rio de Janeiro, Brazil. NPP ranged from 46 g to 173 g dry mass (DM) m−2, whereas SP ranged from 0.90 g DM m−2 to 2.58 g DM m−2. The contribution of allochthonous carbon to the SP was more important than autochthonous sources and varied from 56% to 74% of all basal energy flow assimilated by primary consumers. The annual ingestion rate of basal sources varied from 8.08 g DM m−2 to 26.57 g DM m−2, with the allochthonous material contributing 76% and 87% of this. The annual ingestion rate of autochthonous material varied from 1.2% to 5.5% of the NPP. The present work suggests that the principal energy source for macroinvertebrates in streams of the Guapi‐Macacu catchment came from the riparian forest, as predicted by the RCC. However, this dependence appeared not to be driven by an absolute lack of autochthonous NPP, which seemed more than sufficient to sustain the entirety of macroinvertebrate SP.