Macroinvertebrates are important for processing leaf detritus in temperate streams, but studies about their role in tropical streams often present conflicting results. Via digestive tract analyses, we assessed the diets of Phylloicus sp. larvae (Trichoptera: Calamoceratidae), collected from streams of two southeastern Brazil river basins (Araguari, Sa˜o Francisco). We classified gut contents as coarse particulate organic matter (CPOM), fine particulate organic matter (FPOM), algae, animal tissue, vascular plant tissue and mineral material. We hypothesized that the diets of Phylloicus larvae would be related to the physical habitat of the streams (e.g., riparian vegetation, organic matter availability and morphological characteristics), larval size and river basin. Although FPOM content predominated in both basins, we found greater CPOM content in Phylloicus larvae of Upper Sa˜o Francisco sites, and this food item was related to greater riparian vegetation canopy density. The FPOM content was greater in larvae of Upper Araguari sites, and this food item was correlated with greater instream brush cover. Algae, animal tissue, vascular plant tissue and mineral material were very rare in the digestive tracts, and therefore could not be explained. These results indicate the importance of riparian vegetation structure in modulating feeding habitats of macroinvertebrates. We conclude that the Phylloicus larvae had more flexibility in what they eat than we might expect based on their traditional classification as shredders. Therefore, trusting in published classifications, ignoring regional or local differences, may be inaccurate. Instead, regional studies of feeding habits are needed for accurate classifications of invertebrate taxa into trophic guilds.

Most studies dealing with the use of ecological indicators and other applied ecological research rely on some definition or concept of what constitutes least-, intermediate-and most-disturbed condition. Currently, most rigorous methodologies designed to define those conditions are suited to large spatial extents (nations, ecoregions) and many sites (hundreds to thousands). The objective of this study was to describe a methodology to quantitatively define a disturbance gradient for 40 sites in each of two small southeastern Brazil river basins. The assessment of anthropogenic disturbance experienced by each site was based solely on measurements strictly related to the intensity and extent of anthropogenic pressures. We calculated two indices: one concerned site-scale pressures and the other catchment-scale pressures. We combined those two indices into a single integrated disturbance index (IDI) because disturbances operating at both scales affect stream biota. The local-and catchment-scale disturbance indices were weakly correlated in the two basins (r = 0.21 and 0.35) and both significantly (p < 0.05) reduced site EPT (insect orders Ephemeroptera, Plecoptera, Trichoptera) richness. The IDI also performed well in explaining EPT richness in the basin that presented the stronger disturbance gradient (R 2 = 0.39, p < 0.001). Natural habitat variability was assessed as a second source of variation in EPT richness. Stream size and microhabitats were the key habitat characteristics not related to disturbances that enhanced the explanation of EPT richness over that attributed to the IDI. In both basins the IDI plus habitat metrics together explained around 50% of EPT richness variation. In the basin with the weaker disturbance gradient, natural habitat explained more variation in EPT richness than did the IDI, a result that has implications for biomonitoring studies. We conclude that quantitatively defined disturbance gradients offer a reliable and comprehensive characterization of anthropogenic pressure that integrates data from different spatial scales.

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The use of predictive models in Neotropical basins is relatively new, and applying these models in large basins is hindered by the lack of ecological, geographical, and social-environmental knowledge. Despite these difficulties, we used data from the das Velhas River basin to apply the BEAST (Benthic Assessment of SedimenT) methodology to evaluate and classify the level of environmental degradation. Our two main objectives were to modify and implement the BEAST methodology for use in biomonitoring programs of Brazilian basins, and to test the hypothesis that a gradient of environmental degradation determines a gradient in the structure and composition of benthic macroinvertebrate assemblages. We evaluated 37 sites: 8 in the main river, 15 in the main tributaries with different impact levels, and 14 in tributaries with minimally disturbed conditions (MDC). The BEAST model allowed us to classify 16 test sites: two as natural, four as altered, three as highly altered, and seven as degraded. Our results indicated degradation of the das Velhas River basin near its urban areas. The BEAST model indicated that the pollution gradient found among the sites generated a gradient of the macroinvertebrate assemblages, corroborating the hypothesis.

Here, we set target values to measure the ecological improvement of streams, based on invertebrate communities, riparian vegetation, instream habitat conditions and water chemistry. The study area is a large tropical catchment (Rio das Velhas, Minas Gerais, Brazil) affected by pastures, mining areas and a large urbanized area but also includes natural protected areas. Two stream types were found in the catchment, based on stream size, elevation, climate and geology with significantly different macroinvertebrate communities. In spite of a marked wet/dry seasons' climatic pattern, that does not result in the segregation of communities. Four classes of global degradation (IV-bad to I-good condition) were defined based on the available abiotic information, corresponding to a gradient in structure and biotic metrics of macroinvertebrate communities, matching the current knowledge on taxa sensitivity to pollution and general disturbance. Class I corresponds to target conditions to be achieved under restoration programmes. Using this approach, we were able to detect an improvement of abiotic conditions in four urban streams that benefited from enhancement measures in 2007-2008. However, invertebrate communities improved clearly in only one site (biotic metrics and community structure). Our study highlighted that good water quality alone is not enough and that only the combined effect of water quality, riparian vegetation and instream habitat condition enhancement resulted in the improvement of invertebrate communities. An important limiting factor for macroinvertebrate communities' recovery may be the distance to source populations. We concluded that the combined use of biological and abiotic target values for measuring the recovery of streams is needed to fully achieve an ecological restoration. This approach can also be valuable in the regular monitoring of streams to assess stream degradation. Target values based on other biological elements, such as fishes and algae, and functional processes could also contribute to define more global and realistic goals.

Biotic indices are important tools for evaluating water quality in Biomonitoring Programmes of river basins. The objective of this study was to develop a Benthic Multimetric Index (BMI) to evaluate the water quality in a neotropical catchment in southeastern Brazil. Thirty metrics were evaluated and six were selected to calculate the BMI: family richness, % Oligochaeta, % Chironomidae + Oligochaeta (% CHOL), % EPT (Ephemeroptera, Plecoptera and Trichoptera), % Collector-gatherers, and BMWP-CETEC biotic index. Sampling was carried in triplicate at 21 sampling sites (8 in the river channel and 13 in the tributaries) during 4 annual collecting trips from June 2004 to November 2007, making a total of 945 samples. Scores (5, 3 or 1) were attributed to each chosen metric and were added up to establish the water quality criteria (a score of 6-12 - poor; 13-18 - intermediate; 19-24 - good; and 25-30 - very good water quality). Our results indicated that 48% of the sampling sites analysed in...

Assessing the ecological impacts of anthropogenic pressures is a key task in environmental management. Multimetric indices (MMIs), based on aquatic assemblage responses to anthropogenic pressures, have been used increasingly throughout the world. The MMI approach is a low-cost, rapid field method that produces an aquatic condition index that responds precisely to anthropogenic pressures, making it useful for conservation and environmental management. We developed four candidate MMIs based on benthic macroinvertebrate assemblages sampled at 40 randomly selected sites to assess the environmental condition of streams upstream of a hydroelectric power plant in the Brazilian Neotropical Savanna biome. Those MMIs were built from landscape-adjusted and unadjusted biological metrics as well as two alternative ways of choosing metrics. The alternative MMIs performances were tested by comparing their precision to distinguish least-disturbed areas, responsiveness to discriminate least-and most-disturbed areas, and sensitivity to anthropogenic pressures at catchment and local scales. The best performing MMI had landscape-adjusted metrics and was produced through use of principal component analysis for metric selection. It included 4 metrics: Ephemeroptera richness, average tolerance score per taxon, percentage of predator individuals, and percentage of Odonata individuals adjusted by elevation. This index discriminated well the anthropogenic pressures at local-and catchment-scales, and at both scales simultaneously, as indicated by an integrated disturbance index. Our methodological development included statistical criteria for identifying least-and most-disturbed sites, calibrating for natural landscape variability, and use of non-redundant metrics. Therefore, we expect it will provide a model for environmental assessment of water resources elsewhere in Brazil and in other nations.

Biological diversity can be divided into: alpha (␣, local), beta (␤, difference in assemblage composition among locals), and gamma (␥, total diversity). We assessed the partitioning of taxonomic diversity of Ephemeroptera, Plecoptera and Trichoptera (EPT) and of functional feeding groups (FFG) in neotropical savanna (southeastern Brazilian cerrado) streams. To do so, we considered three diversity components: stream site (␣), among stream sites (␤ 1), and among hydrologic units (␤ 2). We also evaluated the association of EPT genera composition with heterogeneity in land use, instream physical habitat structure, and instream water quality variables. The percentage of EPT taxonomic ␣ diversity (20.7%) was smaller than the ␤ 1 and ␤ 2 diversity percentages (53.1% and 26.2%, respectively). The percentage of EPT FFG collector-gatherer ␣ diversity (26.5%) was smaller than that of ␤ 1 diversity (55.8%) and higher than the ␤ 2 (17.7%) diversity. The collector-gatherer FFG was predominant and had the greatest ␤ diversity percentage among stream sites (␤ 1 , 55.8%). Our findings support the need for implementing regional scale conservation strategies in the cerrado biome, which has been degraded by anthropogenic activities.

Macroinvertebrate identity, not diversity, differed across patches differing in substrate particle size and leaf litter packs in low order, tropical Atlantic forest streams The size of streambed sediment particles is an important determinant of habitat complexity for stream-dwelling invertebrates. In tropical streams we tested if, at the patch scale, sandy substrates were poorer in organisms and taxa when compared with larger grain-size substrates in three experiments: (a) sampling patches with coarse and fine substrates and leaf packs in eight low-order streams, (b) manipulating substrate size at the patch scale in a low-order stream and (c) sampling coarse and fine sediment patches in a larger river. We also investigated the abundance of aquatic hyphomycete conidia in these streams to relate shredder abundance with the presence of fungal decomposers, given that tropical streams are frequently reported as being poor in shredders. In the three experiments, there were consistently no differences in terms of the family richness or total number of invertebrates across the substrate types, but taxa identity differed across substrates. Invertebrate numbers and taxa were positively correlated with current velocity. Macroinvertebrate densities (150-300 individuals/m 2) were lower than those reported in the literature (500->1500 individuals/m 2), but the number of taxa was high (37 families observed, 52 estimated). Shredders comprised 13% of all individuals and 11% of all taxa. The low number of shredders contrasted with the presence of aquatic hyphomycete spores in stream waters and in leaves sampled from the streams. We concluded that the high number of taxa and low number of individuals buffer changes in substrate, allowing the presence of invertebrates even in the less-favorable substrates (sand). Although litter and aquatic hyphomycetes were present in these streams, shredders were poorly represented; this raises the question as to why litter consumers are scarce when resources are abundant in forested tropical streams.

Aims The genus Leiothrix (Eriocaulaceae) is restricted to South America and contains 37 taxa. The genus is most species-rich in the mountains of Minas Gerais, where 25 species occur, 19 of them in the Serra do Cipó. Leiothrix taxa that inhabit different microhabitats exhibit a number of reproductive modes. Rhizomatous taxa produce seeds plentifully; therefore, this group were defined as rhizomatous seed-producing. The pseudoviviparous reproductive mode was divided into canopy-forming and rooted. In the first, ramets remain attached to a parental rosette suspended by scapes, whereas in the second, ramets take root and may or may not remain attached to a parental rosette. In this study, it is proposed that microenvironmental heterogeneity is an important factor generating and maintaining reproductive modes in Leiothrix. † Methods Soil analyses and vegetation cover estimates were performed for five Leiothrix taxa occurring in 19 areas along the Serra do Cipó. In these 19 points of the Serra do Cipó, soil data were collected from 27 populations of each species, and vegetation cover data were collected from 20 populations, due to fire that occurred in the region and destroyed most of the vegetation. For each population, three replicates were made. A discriminant function analysis was performed, in an attempt to test the effect of microhabitat features in the differentiation of the reproductive modes. † Key Results Discriminant function analyses separated the three groups of reproductive modes based mainly on percentage vegetation cover. The pseudoviviparous canopy-forming group occurs under densely crowded conditions, while the pseudoviviparous rooted and rhizomatous seed-producing groups occur in areas with sparse vegetation cover. However, the group pseudoviviparous rooted occurs in soils constituted of exposed sand, while the rhizomatous seed-producing group occurs, frequently, on mat-forming mosses. † Conclusions Microenvironmental heterogeneity, specifically heterogeneity in percentage cover of vegetation, appears to have influenced the generation and maintenance of reproductive modes in Leiothrix. Reproductive variation within Leiothrix taxa occupying different microenvironments results from a response to fine-scale habitat variation. Therefore, it is proposed that ecological speciation is an important process in adaptive radiation in this genus.