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The evaluation of environmental and spatial influence in freshwater systems is crucial for the conservation of aquatic diversity. So, we evaluated communities of Odonata in streams inside and outside sustainable use areas in the Brazilian western Amazon. We predicted that these streams would differ regarding habitat integrity and species α and ß diversity. We also predict that environmental and spatial variables will be important for both suborders, but with more substantial effects on Zygoptera species, considering their nature of forest-specialist. The study was conducted in 35 streams, 19 inside and 16 outside sustainable use areas. The streams outside presented high species richness, abundance, and number of exclusive forest-specialist species from Zygoptera and higher scores of habitat integrity. In contrast, one sustainable use area presented the lowest values of these metrics. Besides, we found that environmental and spatial variables were significantly associated to Zygoptera species composition, but not with Anisoptera, which can be explained by their cosmopolitan nature. Our results indicated that an interplay between environmental and spatial processes determines the structure of the metacommunities of Zygoptera. The less effective dispersal rates and narrow ecological tolerance of Zygoptera species make them more influenced by local conditions and dispersal limitation, and more sensible to habitat modifications. We highlight the importance of improving the local management of the sustainable use areas by environmental agencies, mainly on areas that are losing their capacity to maintain the aquatic fauna, and implementation of social policies toward traditional people.

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In running waters, the concentration of components that define water quality can be subjected to ample fluctuations quantitatively linked to flow rate. If not properly considered, such variability may hinder assessment of the evolution of water quality, of the effects of management actions, and ultimately the understanding of processes driving water quality. The functional response to flow rate was characterized for multiple biogeochemical variables in a pristine, low order stream. Variability of responses spanned between a factor of 2 and > 34, and in all cases were associated to flow rate according to one of three patterns: positive asymptotic (for variables: seston, suspended particles, total nutrients, dissolved and particulated organic matter, dissolved inorganic nitrogen), negative asymptotic (conductivity and dissolved reactive silicon), and humped (dissolved inorganic phosphorous). Building on those results, a rationale is presented for an unambiguous, cost-effective approach to water quality evaluation in running systems with predominantly diffuse sources.

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While land use intensification is a major driver of biodiversity change in streams, the nature of such changes, and at which scales they occur, have not been synthesized. To synthesize how land use change has altered multiple components of stream biodiversity across scales, we compiled data from 37 studies where comparative data were available for species' total and relative abundances from multiple locations including reference (less impacted) streams to those surrounded by different land use types (urban, forestry, and agriculture). We found that each type of land use reduced multiple components of within-stream biodiversity across scales, but that urbanization consistently had the strongest effects. However, we found that ß-diversity among streams in modified landscapes did not differ from ß-diversity observed among reference streams, suggesting little evidence for biotic homogenization. Nevertheless, assemblage composition did experience considerable species turnover between reference and modified streams. Our results emphasize that to understand how anthropogenic factors such as land use alter biodiversity, multiple components of biodiversity within and among sites must be simultaneously considered at multiple scales.

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A new species of Phenacorhamdia is described from Paranapanema River, Upper Paraná River basin, southeastern Brazil. The new species is distinguished from congeners by the combination of following characters 45-46 vertebrae; an entirely dark-brown body; nine pleural ribs; eight branched rays in upper lobe of caudal fin; seven branched rays in pectoral fin; 13 anal-fin rays with 9-10 branched; first basal radial inserted at the 13th vertebrae and eight branchiostegal rays.

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A new species of Hemigrammus is described from the upper Rio Negro, Amazon basin, Brazil. The new species is distinguished from all congeners by its unique color pattern consisting of a single humeral blotch clearly spaced from a conspicuous midlateral dark stripe, which extends from fifth or sixth anteriormost vertical scale row to the basis of the middle caudal-fin rays. Comments on its putative relationships are provided.

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As a part of an assessment of loricariid catfishes inhabiting the Andes of Colombia, specimens belonging to an interesting new species were identified. The new species is described herein, and it is tentatively included in the genus Cordylancistrus. The new species can be easily distinguished among its congeners by the presence of a unique diagnostic character: a fleshy keel or excrescence, black or dark brown, over the posterior tip of supraoccipital. Specimens of the new species were captured in rivers of the Sierra Nevada de Santa Marta and the Sierra de Perijá that drain to the Magdalena River Basin and Caribbean Sea. The occurrence of one species of Cordylancistrus in the Sierra Nevada de Santa Marta could have interesting biogeographic implications for hypotheses related to the geological history of northwestern corner of South America or to the dispersal or vicariance models used to explain biogeographical patterns of related species in Colombia.

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Cyanobacterial blooms are expected to become more frequent in freshwaters globally due to eutrophication and climate change effects. However, our knowledge about cyanobacterial biogeography in the subtropics, particularly in lotic ecosystems, is still very limited and the relationship of blooms to temperature and precipitation remains unclear. We took advantage of a comprehensive database of field data compiled over several years (1997 to 2015) to compare cyanobacteria biomass and distribution between lentic and lotic subtropical freshwaters (36 ecosystems, 30°-35°S) and to investigate the role of water temperature and precipitation as significant predictors in eutrophic ecosystems. A filamentous Nostocales, Dolichospermum (Anabaena), was the most widely distributed and frequent genus in the region of the study, followed by the colonial Microcystis, supporting observations of a global latitudinal pattern. Similar total cyanobacteria biovolumes (TCB) were found in lentic and lotic ecosystems, but the proportion of Dolichospermum was higher in lotic ecosystems. Using generalized linear models (GLMs), we found that temperature and rainfall explained 27% of the variation in TCB in lotic ecosystems, while temperature explained 19 and 28% of Dolichospermum and Microcystis biovolume, respectively. In lentic ecosystems, accumulated rainfall explained 34% of the variation of Microcystis biovolume while temperature explained 64%. Our results imply that the increase in extreme meteorological events and temperature predicted by climate models will promote increasingly severe cyanobacterial blooms in eutrophic subtropical freshwaters. Our analysis provides new information about the occurrence of bloom-forming cyanobacteria for southeastern South America and thus fills an important knowledge gap for subtropical freshwaters.

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Following study of the external morphology and its unmatched variability throughout ontogeny and a re-examination of selected morphological characters based on many specimens of diplomystids from Central and South Chile, we revised and emended previous specific diagnoses and consider Diplomystes chilensis, D. nahuelbutaensis, D. camposensis, and Olivaichthys viedmensis (Baker River) to be valid species. Another group, previously identified as Diplomystes sp., D. spec., D. aff. chilensis, and D. cf. chilensis inhabiting rivers between Rapel and Itata Basins is given a new specific name (Diplomystes incognitus) and is diagnosed. An identification key to the Chilean species, including the new species, is presented. All specific diagnoses are based on external morphological characters, such as aspects of the skin, neuromast lines, and main lateral line, and position of the anus and urogenital pore, as well as certain osteological characters to facilitate the identification of these species that previously was based on many internal characters. Diplomystids below 150 mm standard length (SL) share a similar external morphology and body proportions that make identification difficult; however, specimens over 150 mm SL can be diagnosed by the position of the urogenital pore and anus, and a combination of external and internal morphological characters. According to current knowledge, diplomystid species have an allopatric distribution with each species apparently endemic to particular basins in continental Chile and one species (O. viedmensis) known only from one river in the Chilean Patagonia, but distributed extensively in southern Argentina.

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Helicobacter presence and viability in waters is not well characterized. The identification of natural reservoirs and infection sources may provide novel insights into its waterborne transmission. The goal of this study was to investigated the occurrence of Helicobacter spp. in natural freshwaters from Roraima Tepui, a little studied and unique ecosystem of the Guayana Shield. Freshwaters collected from two localities at Roraima Tepui were cultured in HP selective broth and agar for Helicobacter pylori and analysed by fluorescent in situ hybridization (FISH), specific PCR assays, 16S rRNA gene sequencing and phylogenetic analysis. The presence of other bacteria in freshwater enrichments was determined using clone library sequencing of the 16S rRNA gene and phylogenetic inferences. Helicobacter spp. were detected by semi-nested PCR and FISH in freshwater enrichments from both sites. Coccoid viable but nonculturable (VBNC) cells were evidenced using 16S rRNA gene Helicobacter species and H. pylori-specific probes. Partial 16S rRNA gene sequences of two HP enrichments showed high similarity to H. pylori and Helicobacter nemestrinae (99-100 %). Other bacteria such as Serratia, Aquitalea, Chromobacterium, Mycobacterium, Acinetobacter, Curvibacter and Dysgonomonas were also detected using complete 16S rRNA gene sequences, with Serratia, Aquitalea and Chromobacterium the most common genera (40.9, 18.2 and 15.2 %, respectively). This is the first time that Helicobacter spp. have been reported in freshwaters of a tepui ecosystem. Our results contribute to the current knowledge of these bacteria in the aquatic environment and expand their known/potential sites outside the human host.

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More than 50% of the world's population lives in urban centers. As collection basins for landscape activity, urban waters are an interface between human activity and the natural environment. The microbiome of urban waters could provide insight into the impacts of pollution, the presence of human health risks, or the potential for long-term consequences for these ecosystems and the people who depend upon them. An integral part of the urban water cycle is sewer infrastructure. Thousands of miles of pipes line cities as part of wastewater and stormwater systems. As stormwater and sewage are released into natural waterways, traces of human and animal microbiomes reflect the sources and magnitude of fecal pollution and indicate the presence of pollutants, such as nutrients, pathogens, and chemicals. Non-fecal organisms are also released as part of these systems. Runoff from impervious surfaces delivers microbes from soils, plants and the built environment to stormwater systems. Further, urban sewer infrastructure contains its own unique microbial community seemingly adapted to this relatively new artificial habitat. High microbial densities are conveyed via pipes to waterways, and these organisms can be found as an urban microbial signature imprinted on the natural community of rivers and urban coastal waters. The potential consequences of mass releases of non-indigenous microorganisms into natural waters include creation of reservoirs for emerging human pathogens, altered nutrient flows into aquatic food webs, and increased genetic exchange between two distinct gene pools. This review highlights the recent characterization of the microbiome of urban sewer and stormwater infrastructure and its connection to and potential impact upon freshwater systems.

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En cursos de agua del partido de Tres Arroyos (provincia de Buenos Aires, Argentina) se encontraron sustancias tóxicas (metales pesados, nitratos, nitritos, fluoruros, sustancias fenólicas y pesticidas organoclorados). El objetivo del trabajo fue estimar el riesgo sanitario para el baño recreativo en esas aguas. El análisis se basó en el modelo USEPA probabilístico para riesgo agregado y acumulativo, tanto para efectos no carcinogenéticos (ENC) como carcinogenéticos (EC), considerando la ingesta accidental de agua y el contacto dérmico. Se planteó un escenario de exposición basado en datos propios y de la literatura para un niño de 10 años como representativo de la población expuesta. Los resultados indican que no existiría riesgo relevante para la actividad recreativa para las concentraciones consideradas. De todos los cuerpos de agua el de mayor riesgo es el Arroyo Claromecó, pero sólo alcanza al 20% del valor limitante. Los metales contribuyen con un 82 y 99% del riesgo total acumulado por ENC y EC, respectivamente, seguidos por las sustancias inorgánicas. Y de los metales, el mayor contribuyente al riesgo es el arsénico, quien aporta el 78 y 99% del riesgo agregado y acumulado por todas las sustancias para ENC y EC, respectivamente.

Toxic substances (heavy metals, nitrate, nitrite, fluoride, phenolic substances and organochlorine pesticides) were detected in Tres Arroyos county freshwaters (Buenos Aires province, Argentina). The aim of this study was estimate the human health risk (HR) associated with these substances during recreational bathing. The probabilistic HR assessment was based on aggregated and cumulative USEPA models. Cancer (CE) and non-cancer (NCE) risk were estimated for accidental drinking and dermal contact during the recreational activity. The exposure scenario considered was based on own and literature data, and a ten year-old child was selected as representative of the exposed population. The results indicated that surveyed substances do not generate any health risk for recreational bathing with direct contact at the specified concentrations and exposure conditions. Claromecó creek station was the riskiest point of whole water bodies, but it reaches only 20% of the limitating value. Metals were the major contributors to overall aggregated and cumulative risk (82% for NCE and 99% for CE), followed by inorganic substances. Arsenic was the most dangerous metal, responsible for the 78 and 99% of the aggregate and cumulative risks for all substances for NCE and CE, respectively.

Em cursos d´água da localidade de Tres Arroyos (Província de Buenos Aires, Argentina) foram encontradas substâncias tóxicas (metais pesados, nitratos, nitritos, fluoretos, substâncias fenólicas e pesticidas organoclorados). O objetivo do trabalho foi calcular o risco sanitário para o banho com fins recreativos nessas águas. A análise foi realizada com base no modelo USEPA probabilístico para risco agregado e acumulativo, tanto para efeitos não carcinogênicos (ENC) como carcinogênicos (EC), considerando a ingestão acidental de água e o contato dérmico. Foi apresentado um cenário de exposição com base em dados próprios e da literatura para um menino de dez anos como representativo da população exposta. Os resultados indicam que não existiria risco relevante para a atividade recreativa para as concentrações consideradas. De todos os corpos de água aquele de maior risco é o Arroyo Claromecó mas só atinge 20% do valor limitante. Os metais contribuem com 82 e 99% do risco total acumulado por ENC e EC, respectivamente, seguidos pelas substâncias inorgânicas. E dos metais, o maior contribuinte ao risco é o arsênico, que oferece 78 e 99% do risco agregado e acumulado por todas as substâncias para ENC e EC, respectivamente.

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El dientudo Oligosarcus jenynsii (Günther, 1864) es una de las especies más comunes que habita en la Laguna de Los Padres. Se ha realizado el análisis histológico del hígado del dientudo, un órgano destacable por su sensibilidad a una variedad de factores del medio ambiente. El hígado está compuesto por un parénquima con hepatocitos dispuestos en cordones alrededor de un sinusoide central. El parénquima se halla dividido en lóbulos irregulares por el páncreas exócrino o hepatopáncreas, que posee una disposición acinar y cuyas células se organizan alrededor de una rama de la vena porta. La histomorfología del hígado y la organización del tejido pancreático exócrino de Oligosarcus jenynsii es similar a la de muchos peces teleósteos, tanto marinos como de agua dulce.

The liver is an organ notable for its sensitivity to a great variety of environmental factors. It is composed of a parenchyma divided into irregular lobules by the exocrine pancreas or hepatopancreas; the pancreatic cells are arranged around a branch of the portal vein. The hepatocytes are radially arranged in cords around a central sinusoid. The liver histomorphology and the organization of exocrine pancreatic tissue of O. jenynsii (Günther, 1864) is similar to the acinar morphology of many teleosts, including freshwater and marine species. The aim of the present work was to carry out the histological analysis of the liver of Oligosarcus jenynsii, one of the most common species inhabiting Los Padres Lake (Buenos Aires Province, Argentina).

RESUMO

El dientudo Oligosarcus jenynsii (Günther, 1864) es una de las especies más comunes que habita en la Laguna de Los Padres. Se ha realizado el análisis histológico del hígado del dientudo, un órgano destacable por su sensibilidad a una variedad de factores del medio ambiente. El hígado está compuesto por un parénquima con hepatocitos dispuestos en cordones alrededor de un sinusoide central. El parénquima se halla dividido en lóbulos irregulares por el páncreas exócrino o hepatopáncreas, que posee una disposición acinar y cuyas células se organizan alrededor de una rama de la vena porta. La histomorfología del hígado y la organización del tejido pancreático exócrino de Oligosarcus jenynsii es similar a la de muchos peces teleósteos, tanto marinos como de agua dulce.

The liver is an organ notable for its sensitivity to a great variety of environmental factors. It is composed of a parenchyma divided into irregular lobules by the exocrine pancreas or hepatopancreas; the pancreatic cells are arranged around a branch of the portal vein. The hepatocytes are radially arranged in cords around a central sinusoid. The liver histomorphology and the organization of exocrine pancreatic tissue of O. jenynsii (Günther, 1864) is similar to the acinar morphology of many teleosts, including freshwater and marine species. The aim of the present work was to carry out the histological analysis of the liver of Oligosarcus jenynsii, one of the most common species inhabiting Los Padres Lake (Buenos Aires Province, Argentina).