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Excessive fine sediment (particles <2 mm) deposition in freshwater systems is a pervasive stressor worldwide. However, understanding of ecological response to excess fine sediment in river systems at the global scale is limited. Here, we aim to address whether there is a consistent response to increasing levels of deposited fine sediment by freshwater invertebrates across multiple geographic regions (Australia, Brazil, New Zealand and the UK). Results indicate ecological responses are not globally consistent and are instead dependent on both the region and the facet of invertebrate diversity considered, that is, taxonomic or functional trait structure. Invertebrate communities of Australia were most sensitive to deposited fine sediment, with the greatest rate of change in communities occurring when fine sediment cover was low (below 25% of the reach). Communities in the UK displayed a greater tolerance with most compositional change occurring between 30% and 60% cover. In both New Zealand and Brazil, which included the most heavily sedimented sampled streams, the communities were more tolerant or demonstrated ambiguous responses, likely due to historic environmental filtering of invertebrate communities. We conclude that ecological responses to fine sediment are not generalisable globally and are dependent on landscape filters with regional context and historic land management playing important roles. [ABSTRACT FROM AUTHOR]

Despite long-standing interest, the mechanisms driving aquatic macroinvertebrate drift in tropical streams remain poorly understood. Therefore, the objective of this study was to evaluate which environmental metrics drive macroinvertebrate drift in neotropical sky island streams. We evaluated whether altitude, the abundance of food resources, and variations in water quality influenced macroinvertebrate drift density, diversity, richness, and functional feeding groups. An hypothesis was developed to test whether increased altitude, lower food availability (particulate organic matter), and discharge would increase the density, taxonomic richness, and diversity of drifting invertebrates. Nine headwater stream sites were sampled in the rainy and dry seasons in the Espinhaço Meridional Mountain Range (EMMR) of southeast Brazil. Samples were collected using drift nets deployed from 5:00 p.m. to 8:00 p.m. The abundance of food resources was assessed through estimates of coarse (CPOM) and fine (FPOM) particulate organic matter, and primary producers. CPOM availability was an important explanatory variable for Gathering-Collectors and Scrapers, Altitude was important for Shredders and Predators, and Filtering-Collectors were linked to water discharge, suggesting that functional group drift masses were linked to different ecosystem components. Water temperature, conductivity, dissolved oxygen, current velocity, FPOM biomass and microbasin elevation range exerted little influence on macroinvertebrate drift. Regarding taxa composition, this study also found that Baetidae and Leptohyphidae (Ephemeroptera) and Chironomidae and Simuliidae (Diptera) were the most abundant groups drifting. [ABSTRACT FROM AUTHOR]

Hydropower dams are touted as one of the cleanest forms of energy production, yet they are associated with severe environmental impacts on both the physical structure and functioning of river ecosystems. The threat is particularly acute in the Brazilian Cerrado—a biodiverse savanna region, spanning over 2 million km2, that concentrates the headwaters of several critical South American watersheds. Our study analyzed the current distribution of large and small hydroelectric plants in the Cerrado and focused on understanding their effect on land use changes. We also propose a Dam Saturation Index (DSI) to help spur more integrated planning for this region. Results indicate that the Cerrado river basins contains 116 (30%) of Brazil's large hydroelectric plants and 352 (36%) of its small hydroelectric plants. Moreover, these plants spurred significant land use changes within a 5-km buffer of the dams, with over 2255 km2 of native vegetation cleared by 2000 and an additional 379 km2 in the ensuing 20 years, could reach ~1000 km2. Based on the historical anthropization process in the Brazilian savannas, we expect new crops, pastures, and urban equipment to be incorporated into this landscape, with different impact loads. [ABSTRACT FROM AUTHOR]

Benthic macroinvertebrate assemblages are used to assess anthropogenic stressors and pressures globally—although considerable spatial and temporal variability in those assemblages occur naturally and in their sampling. We evaluated the effects of an untreated domestic sewage spill on the spatial–temporal occurrence, structure and dynamics of benthic macroinvertebrate assemblages, through use of occupancy probability and time series modelling. Our study produced three key results: (1) Site colonization, extirpation, and occupancy probabilities of resistant and sensitive assemblages were not influenced by the predictor variables measured before and after the spill nor between sites. (2) Over time, site occupancy for the proportion of sensitive taxa increased while the proportion of resistant taxa decreased. (3) Artificial substrates reduced natural variability more than Surber sampling of natural substrates, but macroinvertebrate family richness differed over time regardless of sampling device. We conclude that rigorous monitoring and data analyses of benthic bioindicators can be a cost-effective approach for assessing the biotic effects of sewage discharges on neotropical urban streams. [ABSTRACT FROM AUTHOR]

Conditions in freshwater ecosystems are responsible for maintaining biodiversity and other ecosystem services. Identifying and understanding how anthropogenic disturbances affect biotic conditions are important steps in rehabilitating and protecting environmental quality. The relative risk, relative extent, and attributable risk approaches are used to determine ecosystem conditions in ecological monitoring programs conducted across large spatial extents. Our study was conducted in the Pandeiros River basin, which is a protected area in Minas Gerais, Brazil, that contains 233 km of mapped streams that were perennial and accessible. Field sampling was conducted in the dry period (April and June 2016) at 40 randomly selected sites. Ten multimetric indices (MMIs), previously determined to be sensitive in this river basin, were calculated. All the physical habitat disturbance metrics were significantly correlated with the MMIs. The risk of finding poor MMI scores was 1.6–1.7 times higher at sites with a high integrated disturbance index (IDI) or local disturbance index (LDI) score. Pasture was the most extensive disturbance, affecting 40.8% of the stream length, followed by 40.1% for low bed stability, 29% for fine substrates (<16 mm), 24.4% for high IDI scores, and 21.7% for high LDI scores. This is useful to know for five reasons: (1) standardized MMIs can assess environmental quality. (2) MMIs clarify that both catchment and local disturbances may represent serious risks to aquatic assemblages. (3) MMIs indicate which disturbances represent the most risk by comparing MMI scores against disturbance scores. (4) MMI risk assessments facilitate choosing the most appropriate mitigation actions. (5) Our results suggest environmental conservation actions for similar river basins. [ABSTRACT FROM AUTHOR]

Over 70% of the total channel length in all river basins is formed by low order streams, many of which originate on mountaintops. Headwater streams play fundamental roles in processing and transporting terrestrial and aquatic organic matter, often harboring high biodiversity in bottom leaf patches deposited from riparian vegetation. The objective of this study was to assess the variation in taxonomic composition (measured by beta diversity of aquatic macroinvertebrates) among stream sites located in the Espinhaço Meridional Mountain Range, part of a UNESCO Biosphere Reserve in eastern Brazil. We tested two hypotheses. (a) Taxa turnover is the main reason for differences in aquatic insect assemblages within stream sites; we predicted that turnover would be higher than nestedness in all stream sites. (b) Stream site altitude and catchment elevation range are the main explanatory variables for the differences in beta diversity; we predicted that local stream site variables would account for only minor amounts of variation. In both dry and wet seasons, we sampled twice in two habitat types (five leaf patches in pools and five in riffles) in each of nine stream sites distributed in three different river basins. We computed average pairwise beta diversity among sampling stations and seasons in each stream site by using Jaccard and Bray–Curtis indices, and calculated the percentages of diversity resulting from turnover and nestedness. Finally, we tested the degree that local‐ or catchment‐level predictor variables explained beta diversity. We found that turnover was the main component of beta diversity and that both dissolved oxygen and elevation range best explained Bray–Curtis beta diversity. These results reinforce the importance of leaf patches in montane (sky islands) Neotropical savanna streams as biodiversity hotbeds for macroinvertebrates, and that both local and landscape variables explained beta diversity. [ABSTRACT FROM AUTHOR]

Hydropower dams substantially modify lotic ecosystems. Most studies regarding their ecological impacts are based on large dams and provide little information about the far more abundant effects of small hydropower dams. Our aim was to characterize the ecological effects of a small hydropower dam and run‐of‐the‐river reservoir on the structure of benthic macroinvertebrate assemblages in the Pandeiros River located in the neotropical savanna of Brazil. We tested the hypothesis that benthic macroinvertebrate assemblages in sites directly affected by the dam and reservoir would show a different taxonomic structure compared with those in free‐flowing sites. We expected to find sensitive native species associated with the free‐flowing sites, whereas resistant and non‐native invasive taxa were expected in impounded sites. We also explored associations between the presence of native and non‐native invasive taxa to each habitat type. We found that the structure of benthic macroinvertebrate assemblages was significantly different between free‐flowing and impounded sites. Also, we found that the dam and reservoir facilitated colonization of non‐native invasive species (Corbicula fluminea and Melanoides tuberculata) because only in those sites they were found in high abundance, in contrast to the free‐flowing sites. Although the environmental conditions imposed by the impoundment altered the structure of benthic macroinvertebrate assemblages, the effects were limited to sites closest to the dam. Our results highlight the necessity of understanding physical habitat changes caused by the presence and management of run‐of‐the‐river dams and reservoirs. [ABSTRACT FROM AUTHOR]

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, São 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 São 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. [ABSTRACT FROM AUTHOR]

An understanding of the interactions among local environmental factors (e.g., physical habitat and water quality) and aquatic assemblages is essential to conserve biodiversity in tropical and subtropical headwater streams. We evaluated the relative importance of multiple physical and chemical habitat variables that influence the richness of Ephemeroptera, Plecoptera, and Trichoptera (EPT) assemblages in wadeable Brazilian Cerrado (savanna) streams. We sampled macroinvertebrate assemblages and quantified physical and chemical habitat in 79 randomly selected sites in 2 Cerrado basins in southeastern Brazil. The environmental variables selected by multiple regression models (MLRs) via corrected Akaike Information Criteria (AICc) contributed significantly to variation in EPT taxon richness. The variance explained by physical-habitat variables was slightly greater in the Upper São Francisco Basin (adjusted R² = 0.53) than in the Upper Araguari Basin (adjusted R² = 0.46), and both were greater than the variance explained by a combined basin model (adjusted R² = 0.39). Physical-habitat variables were more important than water-quality variables in structuring EPT genera in streams with catchments dominated by agriculture or pasture land uses. Regional models can be improved by incorporating basin-specific information to refine biological assessments and to provide better understanding of the interactions that maintain biodiversity in stream networks. [ABSTRACT FROM AUTHOR]

Landscape and site-scale data analyses aid the interpretation of biological data and thereby help us develop more cost-effective natural resource management strategies. Our study focused on environmental influences on stream assemblages and we evaluated how three classes of environmental variables (geophysical landscape, land use and cover, and site habitat), influence fish and macroinvertebrate assemblage richness in the Brazilian Cerrado biome. We analyzed our data through use of multiple linear regression (MLR) models using the three classes of predictor variables alone and in combination. The four MLR models explained dissimilar amounts of benthic macroinvertebrate taxa richness (geophysical landscape R ≈ 35 %, land use and cover R ≈ 28 %, site habitat R ≈ 36 %, and combined R ≈ 51 %). For fish assemblages, geophysical landscape, land use and cover, site habitat, and combined models explained R ≈ 28 %, R ≈ 10 %, R ≈ 31 %, and R ≈ 47 % of the variability in fish species richness, respectively. We conclude that (1) environmental variables differed in the degree to which they explain assemblage richness, (2) the amounts of variance in assemblage richness explained by geophysical landscape and site habitat were similar, (3) the variables explained more variability in macroinvertebrate taxa richness than in fish species richness, and (4) all three classes of environmental variables studied were useful for explaining assemblage richness in Cerrado headwater streams. These results help us to understand the drivers of assemblage patterns at regional scales in tropical areas. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sampling benthic macroinvertebrates in large rivers has several limitations, arising not only from the selectivity of traditional sampling gears but also from difficulty in capturing organisms that inhabit the deeper zones and high current velocities. Considering the importance of benthic macroinvertebrates as a food resource for fishes, the sampling restrictions in sediment collection done by dredges, and the importance of surveying benthos biodiversity, the objective of this study was to evaluate the stomach contents of five commonly-occurring invertivorous fish species as a means of complementing a benthic macroinvertebrate inventory. Three sampling campaigns (fish and benthic macroinvertebrate) were conducted in a reach of the Araguari River (Minas Gerais, Brazil), approximately 9 km long and 90 m wide. Astyanax altiparanae Garutti & Britski 2000, Leporinus friderici (Bloch 1794), Leporinus amblyrhynchus Garavello & Britski 1987, Iheringichthys labrosus (Lütken 1874) and Pimelodus maculatus Lacepède 1803 were the fish species collected and studied. To determine benthic macroinvertebrate taxonomic richness, a total of 54 Van Veen sediment samples were obtained. We compared lists of the benthic taxa found in fish stomachs with those from the sediment samples. The differences in the taxonomic composition of the benthic macroinvertebrate communities between the sediment samples and each fish species stomachs contents were assessed through NMDS and ANOSIM analyses, using a Sorensen similarity index with the presence/absence of taxa data. Independent of sampling period, additional benthic macroinvertebrate families or classes were provided by identifying fish stomach contents. We found a total of 30 taxa in this study, including 5 unique taxa (or 17% of the total) in the sediment samples, 9 unique taxa (30%) in the stomach samples, and 16 taxa (53%) common to both. The NMDS and ANOSIM analyses showed a significant separation between Van Veen sediment samples and two fish species stomach contents- L. amblyrhynchus and P. maculatus. These results indicate that fish can be used as additional samplers and are an efficient method to complement the benthic taxonomic inventory obtained through traditional sediment sampling techniques in large areas, as river segments and catchments. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this study was to evaluate the influences of detritus from the leaves of different species, and of exposure time on invertebrate colonization of leaves in a shaded Cerrado stream. We hypothesized that the exposure time is the main factor that influences the colonization of leaves by invertebrates. We used leaves of five tree species native to the Brazilian Cerrado: Protium heptaphyllum and Protium brasiliense (Burseraceae), Ocotea sp. (Lauraceae), Myrcia guyanensis (Myrtaceae), and Miconia chartacea (Melastomataceae), which are characterized by their toughness and low-nutritional quality. Litter bags, each containing leaves from one species, were placed in a headwater stream and removed after 7, 15, 30, 60, 90, and 120 days. The dominant taxon was Chironomidae, which comprised ca. 52% of all organisms and ca. 20% of the total biomass. The taxonomic richness of colonizing organisms did not vary among the leaf species. However, the density and biomass of the associated organisms varied differently among the kinds of detritus during the course of the incubation. The collector-gatherers and shredders reached higher densities in the detritus that decomposed more rapidly ( Ocotea sp. and M. guyanensis), principally in the more advanced stages of colonization. The collector-filterers reached higher densities in the detritus that decomposed more slowly ( P. heptaphyllum, P. brasiliense, and M. chartacea), principally in the initial stages of incubation. A cluster analysis divided the detritus samples of different leaf species according to the exposure time (initial phase: up to 7 days; intermediate phase: 7–30 days; advanced phase: 30–120 days), suggesting some succession in invertebrate colonization, with differences in taxon composition (indicator taxa analysis). These results suggest that regardless of the leaf-detritus species, exposure time was the main factor that influenced the colonization process of aquatic invertebrates. [ABSTRACT FROM AUTHOR]

Copyright of Neotropical Biology & Conservation is the property of Pensoft Publishers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

1. Lotic ecosystems can be studied on several spatial scales, and usually show high heterogeneity at all of them in terms of biological and environmental characteristics. Understanding and predicting the taxonomic composition of biological communities is challenging and compounded by the problem of scale. Additive diversity partitioning is a tool that can show the diversity that occurs at different scales. 2. We evaluated the spatial distribution of benthic macroinvertebrates in a tropical headwater catchment (S.E. Brazil) during the dry season and compared alpha and beta diversities at the scales of stream segments, reaches, riffles and microhabitats (substratum types: gravels, stones and leaf litter). We used family richness as our estimate of diversity. Sampling was hierarchical, and included three stream segments, two stream reaches per segment, three riffles per reach, three microhabitats per riffle and three Surber sample units per microhabitat. 3. Classification analysis of the 53 families found revealed groups formed in terms of stream segment and microhabitat, but not in terms of stream reaches and riffles. Separate partition analyses for each microhabitat showed that litter supported lower alpha diversity (28%) than did stones (36%) or gravel (42%). In all cases, alpha diversity at the microhabitat scale was lower than expected under a null model that assumed no aggregation of the fauna. 4. Beta diversity among patches of the microhabitats in riffles depended on substratum type. It was lower than expected in litter, similar in stone and higher in gravel. Beta diversities among riffles and among reaches were as expected under the null model. On the other hand, beta diversity observed was higher than expected at the scale of stream segments for all microhabitat types. 5. We conclude that efficient diversity inventories should concentrate sampling in different microhabitats and stream sites. In the present study, sampling restricted to stream segments and substratum types (i.e. excluding riffles and stream reaches) would produce around 75% of all observed families using 17% of the sampling effort employed. This finding indicates that intensive sampling (many riffles and reaches) in few stream segments does not result in efficient assessment of diversity in a region. [ABSTRACT FROM AUTHOR]

The aims of this study were to determine which linear body dimensions are best suitable and which mathematical functions can be used to describe length-dry mass relationships for a population of Phylloicus sp. (Trichoptera: Calamoceratidae) larvae. We measured three linear body dimensions (body length, head capsule width and interocular distance) of 54 larvae to use as dry mass predictors. For the description of length-dry mass relationships we used linear, exponential and power function models. Body length provided the best fitted equations to estimate biomass, followed by head capsule width and interocular distance. The highest coefficients of determination were found in power function and exponential models. These relationships can be useful to determine the growth rate and/or secondary production of Phylloicus larvae in future laboratory experiments, as well as to understand the importance of these shredders in the energy flux of shaded tropical streams. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: We assessed leaf breakdown of five native riparian species from Brazilian Cerrado (Myrcia guyanensis, Ocotea sp., Miconia chartacea, Protium brasiliense, and Protium heptaphyllum), incubated in single and mixed species packs in two headwater streams with different physico-chemical properties in the Espinhaço Mountain range (Southeastern Brazil). Leaves were placed in plastic litter bags (15cm×20cm, 10mm mesh size) and the experiments were carried out during the dry seasons of 2003 and 2004. Leaf nitrogen and phosphorus contents were similar in all species, but polyphenolic contents were different (P<0.001). M. guyanensis showed higher polyphenolics content (8.48%g−1 dry mass) and leaf toughness. Individually, higher breakdown rates were found in M. guyanensis at Indaiá stream (k=0.0063±0.0005d−1) and in Ocotea sp. at Garcia stream (k=0.0088±0.0006d−1). However, P. brasiliense and P. heptaphyllum showed lower breakdown rates at Indaiá and Garcia streams (Indaiá: k=0.0020±0.0002 and 0.0019±0.0001d−1; Garcia: k=0.0042±0.0001 and 0.0040±0.0002d−1). Single and mixed breakdown processes of each species were not statistically different on both streams. However, all species showed higher breakdown rates at Garcia stream (P<0.01). These results suggest that leaf breakdown is not altered when litter benthic patches are composed by a mixture of species in the same proportions that they occur on riparian leaf falls. [Copyright &y& Elsevier]

The Ibirité watershed is subject to several forms of environmental degradation such as the presence of a petroleum refinery industry, urbanization of its surrounding landscape, and non treated domestic sewage from over 135,000 inhabitants. Benthic macroinvertebrates represent a useful tool in the evaluation of environmental quality through studies of the structure of communities and their relationship to anthropic activities within the watersheds. The objective of this study was to evaluate the environmental impact to the Ibirité reservoir caused by the petroleum refinery industry, urbanization, and sulphatation. Degradation of the watershed was measured by using the richness, diversity, evenness, and density of benthic macroinvertebrates. Twelve sampling stations were established as follows: five stations on Pintados and Ibirité streams (upstream from the reservoir), six in the reservoir and one station downstream from the reservoir. From 2002 to 2003, during both the dry and rainy seasons (in the tributaries) and the stratified and non-stratified periods (in the reservoir) were evaluated. A total of 289,777 organisms were collected and the most abundant organisms found in the streams were Oligochaeta (60%), Chironomidae ( Chironomus, Goeldichironomus, Dicrotendipes, Cryptochironomus, Polypedilum, Parachironomus, Tanytarsus, Tribelos, Tanypus, Ablabesmyia, Cricotopus, Oliveriella) (38%) and Gastropoda ( Biomphalaria straminea, Physa sp., Melanoides tuberculatus, Pomacea haustrum) (2%). In the reservoir, the most abundant specimens were Chaoboridae (46%) and Chironomidae larvae ( Chironomus, Goeldichironomus, Tanypus, Coleotanypus, Labrundinia) (17%), in addition to Oligochaeta (24%) and Gastropoda ( Melanoides tuberculatus) (13%). Evaluation of the structure and distribution of benthic communities showed a rapid environmental degradation process within the studied aquatic systems, in which low values of richness and diversity and high densities of tolerant organisms were observed. This environmental degradation is a result of the intense discharge of domestic sewage into the streams, reducing water quality and contributing to rapid artificial eutrophication. [ABSTRACT FROM AUTHOR]

The diversity and composition of drift invertebrate assemblages were evaluated along a longitudinal gradient of an altitudinal stream in southeastern Brazil. The main goal of this study was to evaluate the influence of seasonality, stream order, and some abiotic factors on invertebrate drift and the use of drifting invertebrate assemblages to assess aquatic invertebrate diversity. Drift samples were collected over a 24 h period using nets (open area of 0.08 m2; mesh 0.250 mm), partially submerged (60%) in the water column. Taxonomic richness, Pielou evenness (J), Shannon-Wiener diversity (H'), and total density of drift invertebrate assemblages were used in unpairedt-tests, Kruskal-Wallis and stepwise multiple regression analysis. The results showed a high taxonomic richness of aquatic invertebrates, with 91taxafound. Chironomidae and Ephemeroptera represented together c. 80% of the total density of drift organisms. The drift approach allowed the collection of new and raretaxa, besides the knowledge of pupae stage of several chironomid genera. Significant differences in the taxonomic richness and diversity of drift invertebrate assemblages were found between the rainy and dry periods, indicating a significant influence of seasonality. An increase in water flow and electrical conductivity were associated with the increase in the taxonomic richness and diversity in the rainy period. No significant differences were found among the other abiotic variables among the stream orders. [ABSTRACT FROM AUTHOR]

The state of Minas Gerais still has some nearly pristine aquatic ecosystems, thus representing strategic aquatic resources for Brazil. Rivers and creeks of Serra do Cipó (19° -20°S, 43° -44°W) constitute an example of natural ecosystems in preserved conditions where a broad research project was initiated in 1996 aimed at the assessment of aquatic biodiversity and water quality characterisation. This area is the natural water division between the hydrographic basins of Doce and São Francisco rivers, two of the most important watersheds of Minas Gerais. The main goal of this study was to assess the diversity of benthic macroinvertebrate communities and use them as bioindicators of water quality. A secondary goal was to classify the benthic communities into three categories: 1) non-affected communities: those preserving a pristine structure, which are significant for fragile ecosystems, 2) median-affected communities: those receiving some degree of impacts, formed by a mixture of stenotopic and euritopic populations capable of adapting to new conditions thus reflecting the ecosystem's resilience, and 3) heavily-affected communities: those with very poor diversity, generally subject to severe human impact with destructive effects, but that are still important for the functioning of these degraded ecosystems. [ABSTRACT FROM AUTHOR]

• We summarize a long-term ecological research in a megadiverse montane grassland. • We provide data on climate, soil, plant communities, plant mutualists and antagonists. • Our goal is to integrate information into global mountain assessment networks. Campo rupestre is a megadiverse vegetation mosaic dominating one of the world's geologically oldest tropical mountains. The campo rupestre hosts nearly 15% of Brazil's flora, with 40% of endemism in an area smaller than 1% of the national territory. Here, we summarize and explain the rationale underlying the long-term ecological research at Serra do Cipó (LTER-CRSC), in southeastern Brazil. The LTER-CRSC is a multi-taxa monitoring initiative focused on ecological patterns and processes along elevational gradients. We explain the standardized sampling methods of the LTER-CRSC and provide original data on climate, soil, and biodiversity along an elevational gradient. In our view, the LTER-CRSC offers a remarkable opportunity to improve predictions on how global change drivers affect biodiversity and ecosystem functioning in tropical, snow-free mountains. Our ultimate goal is to integrate the data from this study into a growing database from global mountain assessment networks and LTERs. We hope this initiative will stimulate collaboration and lead to further LTER sites being established in tropical mountains. Such efforts are needed as a basis for scientifically-based policy making, especially aimed at mitigating the effects of global change on tropical biodiversity and ecosystem functioning. [ABSTRACT FROM AUTHOR]

Reservoirs are artificial ecosystems with multiple functions having direct and indirect benefits to humans; however, they also cause ecological changes and influence the composition and structure of aquatic biota. Our objectives were to: (1) assess the environmental condition of Nova Ponte Reservoir, Minas Gerais state, southeastern Brazil; and (2) determine how the aquatic biota respond to disturbances. A total of 40 sites in the littoral zone of the reservoir were sampled to characterize physical and chemical habitat, land use, and benthic macroinvertebrate and fish assemblages. The predominant type of land cover near the reservoir was natural vegetation. A total of 29 fish species and 39 macroinvertebrate taxa were collected, including eight alien species. Most sites had intermediate levels of human disturbance, however, high levels of degradation were associated with high proportions of alien species. Disturbances at multiple scales may alter natural patterns and processes, leading to environmental changes and damaging biological communities. Our results reinforce the importance of assessing reservoir ecological conditions at several scales. The study of land use, littoral zone physical habitat characteristics, water quality, and assemblage structure set the ground for proposing actions to rehabilitate and conserve aquatic ecosystems. [ABSTRACT FROM AUTHOR]

• Trait-based approach for assessing Odonata larvae responses to anthropogenic impact. • Odonata larvae have different traits comparing least and highly disturbed streams. • Odonata larvae traits can be a useful tool for assessing anthropogenic impacts. Headwater streams are facing increasing disturbances from human pressures worldwide, thus better knowledge about bioindicators, particularly aquatic insect responses to various pressures and stressors, are urgently needed. Multiple trait-based approaches consider species attributes filtered by the environment, allowing them to persist in ecosystems under environmental pressures. Because this approach has been minimally explored in Odonata larvae, we aimed to understand how anthropogenic stressors structure Odonata larval assemblages in neotropical savanna streams by using multiple trait-based approaches. We hypothesized that a set of stressors--such as reduced substrate heterogeneity, poor water quality, natural land cover converted to pasture and agriculture, and reduced local riparian canopy cover--select Odonata functional traits. We collected 3209 Odonata larvae from 186 neotropical savanna headwater stream sites and used 39 environmental variables and seven traits in 23 categories related to their functional roles in Odonata genera. To assess associations between trait categories and environmental variables, we applied RLQ and fourth-corner statistical analyses. We found strong relationships between environmental variables and sets of Odonata biological traits that were separated into two main groups. Zygoptera genera (Perilestes , Allopodagrion , Heliocharis , Argia , Epipleoneura , Mnesarete/Hetaerina , Psaironeura) have elongated body shapes, caudal lamellae respiration, conforming thermoregulation, and endophytic oviposition. Such traits favor assemblages in conditions similar to reference streams, including denser riparian vegetation, good water quality, and diverse flows and substrate. Therefore, they are more sensitive to changes in those conditions. On the other hand, Anisoptera genera (Gomphoides , Archaeogomphus , Macrothemis, Brechmorhoga , Gynothemis , Phyllocycla) have cylindrical body shapes, internal gill respiration, endothermic thermoregulation, and burrowing behavior. Those traits facilitate their survival in intermediate or disturbed stream sites, characterized by riparian deforestation, increased erosion and siltation, and higher levels of total dissolved solids and conductivity. Therefore, using Odonata larval traits can be a valuable tool for assessing and monitoring anthropogenic impacts on neotropical savanna streams. [ABSTRACT FROM AUTHOR]

• Effectiveness of multimetric indices in environmental quality assessment. • Ten MMIs from multiple continents were effective for evaluating ecological conditions. • Even in protected areas, local disturbances affected biological condition. The quality and availability of water resources in tropical watersheds are threatened by increased multiple use demands by human populations. Therefore, there is a need for cost-effective ecological indicators of water body status and trends. Multimetric indices (MMIs), based on responses of biological assemblages to anthropogenic disturbances, are excellent examples of such indicators and they have been applied globally. However, creating new MMIs for each water body or study area requires considerable analytical effort and hinders our ability to make regional or global comparisons. Therefore, we tested the effectiveness of 17 published benthic macroinvertebrate MMIs for assessing the environmental quality of a tropical anthropogenically least-disturbed river basin in the Neotropical Savanna (Brazilian Cerrado) biome. We tested those MMIs through use of macroinvertebrate data sampled at 40 stream sites in the Pandeiros River basin, Brazil. Disturbances in the basin were related to local factors such as pasture, garbage, and cropland in stream riparian areas. Index performance was tested by comparing precision, bias, responsiveness and sensitivity to anthropogenic pressures and stressors. Ten indices performed satisfactorily in evaluating the environmental condition of the basin. Therefore, we do not recommend developing new benthic MMIs for rapid environmental quality assessments. On the other hand, we do recommend using standard data collection methods for evaluating conditions throughout the biome. [ABSTRACT FROM AUTHOR]