Predicting downstream transport distance of fish eDNA in lotic environments.

Environmental DNA (eDNA) is an effective tool for describing fish biodiversity in lotic environments, but the downstream transport of eDNA released by organisms makes it difficult to interpret species detection at the local scale. In addition to biophysical degradation and exchanges at the water-sediment interface, hydrological conditions control the transport distance. A new eDNA transport model described in this paper considers downstream retention and degradation processes in combination with hydraulic conditions and assumes that the sedimentation rate of very fine particles is a correct estimate of the eDNA deposition rate. Based on meta-analyses of available studies, the particle size distribution of fish eDNA (PSD), the relationship between the sedimentation rate and the size of very fine particles in suspension, and the influence of temperature on the degradation rate of fish eDNA were successively modelled. After combining the results in a mechanistic-based model, the eDNA uptake distances (distance required to retain 63.21% of the eDNA particles in the riverbed) observed in a compilation of previous experimental studies were correctly simulated. eDNA degradation is negligible at low flow and temperature but has a comparable influence to background transfer when hydraulic conditions allow a long uptake distance. The wide prediction intervals associated with the simulations reflect the complexity of the processes acting on eDNA after shedding. This model can be useful for estimating eDNA detection distance downstream from a source point and discussing the possibility of false positive detection in eDNA samples, as shown in an example.

Taxonomic Contributions on Macrogynoplax Enderlein and Enderleina Jewett (Plecoptera: Perlidae) from Brazil, Including a New Species Supported by Molecular and Morphological Data.

Stoneflies (Plecoptera) are aquatic insects widely used in ecological and monitoring studies as indicators of environmental quality due to their high sensitivity to pollution. Among Brazilian Plecoptera, Perlidae is the most diverse family, with four genera (Anacroneuria Klapálek 1909, Enderleina Jewett 1960, Kempnyia Klapálek 1914, and Macrogynoplax Enderlein 1909) and about 150 species. Herein, based on data from the barcode region of the mitochondrial cytochrome c oxidase subunit I (COI) gene and morphological characters, we studied specimens of Enderleina and Macrogynoplax, mainly from the Brazilian Savanna. Our alignment with a total length of 608 base pairs included 23 COI sequences, of which 10 are new and 13 were obtained from GenBank. The sequences and congruence of the obtained species clusters were analyzed using neighbor joining. As a result, we describe a new species of Enderleina, the first of this genus in the Brazilian Savanna, and update the geographic distribution of some Macrogynoplax species. A new record was included for Macrogynoplax veneranda Froehlich 1984 in São Paulo state and the first record of M. yupanqui Stark 1996 in Brazil was also included. First records were made for Macrogynoplax matogrossensis Bispo and Neves 2005 and a Macrogynoplax specimen in Goiás and Bahia states, respectively. Consequently, we expanded the distribution of the genus in the Brazilian Savanna and Atlantic Forest. In addition, we provide observations on the morphological differences found among these species, discuss about the distribution of the genera, present molecular data discussing their contributions to the knowledge of the genus, and comment on the recommendations for future research considering a scenario of integrative approaches. Lastly, we present a key to identify the adult males of Enderleina.

Spatial Variation of Cladophora Epiphytes in the Nan River, Thailand.

Cladophora is an algal genus known to be ecologically important. It provides habitats for microorganisms known to provide ecological services such as biosynthesis of cobalamin (vitamin B12) and nutrient cycling. Most knowledge of microbiomes was obtained from studies of lacustrine Cladophora species. However, whether lotic freshwater Cladophora microbiomes are as complex as the lentic ones or provide similar ecological services is not known. To illuminate these issues, we used amplicons of 16S rDNA, 18S rDNA, and ITS to investigate the taxonomy and diversity of the microorganisms associated with replicate Cladophora samples from three sites along the Nan River, Thailand. Results showed that the diversity of prokaryotic and eukaryotic members of Cladophora microbiomes collected from different sampling sites was statistically different. Fifty percent of the identifiable taxa were shared across sampling sites: these included organisms belonging to different trophic levels, decomposers, and heterotrophic bacteria. These heterogeneous assemblages of bacteria, by functional inference, have the potential to perform various ecological functions, i.e., cellulose degradation, cobalamin biosynthesis, fermentative hydrogen production, ammonium oxidation, amino acid fermentation, dissimilatory reduction of nitrate to ammonium, nitrite reduction, nitrate reduction, sulfur reduction, polyphosphate accumulation, denitrifying phosphorus-accumulation, and degradation of aromatic compounds. Results suggested that river populations of Cladophora provide ecologically important habitat for microorganisms that are key to nutrient cycling in lotic ecosystems.

Diel variation of aquatic insect drift in streams of Southern Brazil

Some organisms, such as aquatic insects, are transported from the upstream to downstream region of streams through a process called drift. This process occurs in passive and active ways and can be variable throughout the day, mainly between the nocturnal and diurnal periods. Here, we evaluate the periodicity of the drift of aquatic insects in two streams of the Middle Iguaçu basin, southern region of Brazil. We predicted that the drift of aquatic insects brings the highest richness, diversity and abundance during the nocturnal period, compared to the diurnal period. In addition, we expected that the composition of species is different between these periods. In each stream, aquatic insect sampling was carried out 10 times, for 24 hours, using drift nets. A total of 2,114 aquatic insect specimens were recorded, distributed in 26 families. Of these families, 20 were recorded during the diurnal period and 24 during the nocturnal period. Our results showed an increase in the diversity and abundance of aquatic insect drift in the nocturnal period. However, only abundance was significantly different between the periods. We attribute the higher abundance in nocturnal drift possibly to biological interactions. Thus, nocturnal drift can be a strategy of some aquatic insects to avoid visual predation by other invertebrates and/or vertebrates, in Neotropical streams. We highlight the importance of our study, because it can be used for comparison in surveys of lotic environments that have been impacted by human activity (e.g. by dam construction), which can alter the water flow, and consequently the pattern of insect drift.

Small is better: comparing the efficiency of two Surber samplers' sizes for biomonitoring programs in tropical headwater streams in the Amazon region.

This study aimed to compare the efficiency of two different sizes of the Surber sampler to assess benthic macroinvertebrates in headwater streams in two Amazonian regions. Two Surber samplers of different sizes were used, one measuring 20 × 20 cm and the other 30 × 30 cm, both with a 0.25-mm net. The number of replicates taken was 6 for the smaller sampler and 3 for the bigger one, maintaining approximately the same total sampled area. The study was carried out in 12 headwater streams with different environmental conditions. Biological metrics were calculated for each size at each site and compared within each stream health category. A two-way analysis of similarities test was performed to compare the community structure assessed by each method at each stream. A normalized sampling effort was used to quantify the number of samples required to correctly sample each site. The data did not show a significant difference between the two sizes regarding the taxonomic recruitment and the community structure sampled at each stream, but differences were found between the two sizes in dominance values and in Shannon index scores for the natural sites. Furthermore, the smaller Surber was able to assess 70% of the estimated richness in all sites, which suggests that it is better to assess benthic macroinvertebrates than the larger Surber. Moreover, the smaller Surber is easier to transport in the field, reducing the effort of the technician, and takes less time to sort the material collected with it, which can reduce the sample processing effort, therefore reducing the cost of the project.

Condition Index, Reproduction and Feeding of Three Non-Obligatory Riverine Mekong Cyprinids in Different Environments.

Condition index, reproduction and feeding of three non-obligatory riverine Mekong cyprinids namely Hampala dispar, Hampala macrolepidota and Osteochilus vittatus were examined. The samples were from the Nam Ngiep (NN) River and Bueng Khong Long (BKL) Swamp, which are the representative of the lotic- and lentic-environments, respectively. These two habitats lay in the same geographical area but on the opposite banks of the Mekong mainstream. The samplings were conducted between May 2017 and April 2018. There were 365 H. dispar, 259 H. macrolepidota and 298 O. vittatus samples in this study. The condition index of all three species were beyond 90% implying they can live well in both lotic and lentic environments. Reproductions of all three species were taken place in both environments with two peaks at the onset and end of rainy season. The samples from BKL showed early maturation than NN samples in all three (3) species. Feeding plasticity, though dominant by insects, was observed in Hampala spp., while O. vittatus can utilise any available detritus in both environments. Results clearly show that all the three selected non-obligatory riverine fish species can live very well in either lotic or lentic environments and imply that they can adjust themselves to reservoir environment.

Gomphonema Ehrenberg (Bacillariophyceae, Gomphonemataceae) of the São Francisco Falso River, Paraná, Brazil / Gomphonema Ehrenberg (Bacillariophyceae, Gomphonemataceae) do rio São Francisco Falso, Paraná, Brasil

Abstract: Gomphonema Ehrenberg is a genus well represented in periphytic algal flora of epicontinental environments. The substrate colonization is facilitated by the secretion of mucilage by the pore field, allowing cell adhesion. Samples were scraped off and analyzed from vegetative portions of the macrophyte Eichhornia azurea Kunth, collected in São Francisco Falso River, located in Santa Helena City, Paraná State. The sampling occurred in four different sites, in four different periods, totaling 16 samples. The quantitative material analysis resulted in 28 identified taxa, in which Gomphonema brasiliense ssp. pacificum, Gomphonema neoapiculatum Lange-Bertalot, Reichardt & Metzeltin Gomphonema pantropicum Reichardt and Gomphonema perapicatum Metzeltin & Lange-Bertalot represented pioneer citations for Paraná diatomflorula. The ultrastructure observations of some species were crucial to distinguish a few taxa, as Gomphonema brasiliense and Gomphonema brasiliensoide D. Metzeltin, Lange-Bertalot & F. García-Rodríguez. We suggest future studies in this environment, once it has propitious characteristics to the development of epilithic diatoms. Moreover, phylogenetic studies are also recommended for a better distinction of taxa with a wide morphologic variation.

Resumo: Gomphonema Ehrenberg é um gênero bem representado na flora algal perifítica de ambientes epicontinentais. A colonização de substratos é facilitada pela secreção de mucilagem pelo campo de poros permitindo a adesão das células. As amostras analisadas foram removidas das porções vegetativas da macrófita Eichhornia azurea Kunth, coletadas no rio São Francisco Falso, localizado no município de Santa Helena, Paraná. As coletas ocorreram em quatro estações de amostragem, em quatro períodos diferentes, totalizando 16 amostras. A análise qualitativa do material resultou na identificação de 28 táxons, sendo que Gomphonema brasiliense ssp. pacificum, Gomphonema neoapiculatum Lange-Bertalot, Reichardt & Metzeltin Gomphonema pantropicum Reichardt e Gomphonema perapicatum Metzeltin & Lange-Bertalot constituíram citações pioneiras para a diatomoflórula do Paraná. As observações da ultra-estrutura de algumas espécies foram decisivas para distinção entre alguns táxons, como por exemplo, Gomphonema brasiliense Grunow e Gomphonema brasiliensoide D. Metzeltin, Lange-Bertalot & F. García-Rodríguez. Sugerem-se futuros estudos desse ambiente, uma vez que o mesmo possui características propícias ao desenvolvimento de diatomáceas epilíticas, além de estudos filogenéticos para melhor distinção dos táxons com ampla variação morfológica.

Avaliação da qualidade da água do Rio Tibagi antes da formação do reservatório da UHE Mauá, por meio de análise fatorial / Water quality evaluation of Tibagi river before the filling of Mauá HPP reservoir, using factor analysis

RESUMO Ecossistemas afetados pela formação de reservatórios passam por monitoramentos compulsórios antes, durante e após a construção do empreendimento. Esses programas de monitoramento geram extensas matrizes de dados, que visam atender às condicionantes de licenciamento ambiental bem como à gestão dos recursos hídricos. No intuito de gerar informações que propiciem o gerenciamento de recursos hídricos, o presente trabalho visou avaliar a qualidade de água do Rio Tibagi, localizado no estado do Paraná, antes da construção da usina hidrelétrica de Mauá. Foram utilizados dados de quatro das oito estações do Programa de Monitoramento das Condições Limnológicas do Rio Tibagi, descrito no Plano Básico Ambiental da referida usina. Os dados selecionados compreenderam o período entre dezembro de 2009 e abril de 2012. Após o tratamento dos dados, por meio de análise fatorial, foram avaliados os fatores descritores da qualidade de água, visando à caracterização das águas na região do futuro empreendimento. De forma geral, os fatores retidos demonstraram a influência antrópica no recurso hídrico. Mesmo apresentando pequena variação na composição do fator 1, entre as estações de monitoramento, esse fator foi caracterizado especialmente pelas variáveis fósforo total, sólidos totais e coliformes termotolerantes. A presença da variável coliformes termotolerantes na composição do fator é um indicativo comum de poluição a partir de esgotos domésticos não tratados, sendo o mesmo aplicável ao fósforo, que assim como os sólidos totais, também pode ser advindo do uso inadequado do solo no entorno.

ABSTRACT Ecosystems affected by the formation of reservoirs are subjected to compulsory monitoring before, during and after the construction of the power plant. These monitoring programs generate large database that aim to satisfy environmental licensing conditions, as well as the management of water resources. In order to generate information that would facilitate the management of water resources, this study aimed to evaluate the quality of Tibagi river water located in Paraná State, Brazil, before the construction of the Mauá hydroelectric power plant (HPP). Data from four of the eight stations described in the Limnological Conditions Monitoring Program of the Tibagi river described in the HPP's Basic Environmental Plan were analyzed. The selected data comprises the period between December 2009 and April 2012, before the HPP installation. In general, the retained factors demonstrated the anthropogenic influence on the water resources. Even with a small variation in the composition of the factor 1 in the monitored stations, this factor was especially characterized by the variables: total phosphorus, total solids, and fecal coliforms. The presence of fecal coliforms in the factor's composition is a common indicator of pollution from untreated domestic sewage. The same applies to total phosphorus, which, as well as the total solids, can also be related to the inappropriate land use in the vicinity.

Immature Odonata-Anisoptera in the Iguatemi river basin, upper Paraná River, Mato Grosso do Sul State, Brazil / Imaturos de Odonata-Anisoptera da bacia do rio Iguatemi, alto rio Paraná, Mato Grosso do Sul, Brasil

This study present an inventory of the genera of Odonata-Anisoptera in lotic environments of the Iguatemi River basin, upper Paraná River, Mato Grosso do Sul State, Brazil. Samplings were performed from December 2006 to February 2009 in the Iguatemi River and eight streams of the basin. We collected 739 immature Odonata, distributed in 25 genera and three families; of which one genus represent a new record for the Mato Grosso do Sul State. Progomphus, Tramea, Elasmotemis, Macrothemis, Aphyla and Phylocycla were the most representative genera in the Iguatemi River basin. The genus accumulation curve predicts an increase of new genera for the Iguatemi River basin.

Este trabalho apresenta um inventário de gêneros de Odonata-Anisoptera em ambientes lóticos da bacia do rio Iguatemi, alto rio Paraná, Mato Grosso do Sul, Brasil. As amostragens ocorreram no período de dezembro de 2006 a fevereiro de 2009 no rio Iguatemi e em oito riachos distribuídos na bacia. Foram coletados 739 imaturos de Odonatas, distribuídos em 25 gêneros e três famílias, do qual um gênero representa um novo registro para o Estado de Mato Grosso dos Sul. Progomphus, Tramea, Elasmotemis, Macrothemis, Aphyla e Phylocycla foram os gêneros mais representativos na bacia do rio Iguatemi. A curva de acumulação de gênero sugere a expectativa de incremento de novos gêneros para a bacia do rio Iguatemi.

Characterization of the microbial community in a lotic environment to assess the effect of pollution on nitrifying and potentially pathogenic bacteria / Caracterização da comunidade microbiana em um ambiente lótico para acessar o efeito da poluição em bactérias nitrificantes e potencialmente patogênicas

This study aimed to investigate microbes involved in the nitrogen cycle and potentially pathogenic bacteria from urban and rural sites of the São Pedro stream. Water samples were collected from two sites. A seasonal survey of bacterial abundance was conducted. The dissolved nutrient content was analysed. PCR and FISH analysis were performed to identify and quantify microbes involved in the nitrogen cycle and potentially pathogenic bacteria. The seasonal survey revealed that the bacterial abundance was similar along the year on the rural area but varied on the urban site. Higher concentration of dissolved nutrients in the urban area indicated a eutrophic system. Considering the nitrifying microbes, the genus Nitrobacter was found, especially in the urban area, and may act as the principal bacteria in converting nitrite into nitrate at this site. The molecular markers napA, amoA, and nfrA were more accumulated at the urban site, justifying the higher content of nutrients metabolised by these enzymes. Finally, high intensity of amplicons from Enterococcus, Streptococcus, Bacteroides/Prevotella/Porphyromonas, Salmonella, S. aureus, P. aeruginosa and the diarrheagenic lineages of E. coli were observed at the urban site. These results indicate a change in the structure of the microbial community imposed by anthrophic actions. The incidence of pathogenic bacteria in aquatic environments is of particular importance to public health, emphasising the need for sewage treatment to minimise the environmental impacts associated with urbanisation.

Este estudo objetivou investigar os micro-organismos envolvidos no ciclo do nitrogênio e bactérias potencialmente patogênicas das áreas urbanas e rurais do Córrego São Pedro. Amostras de água foram coletadas dos dois locais. Um levantamento sazonal da densidade bacteriana foi realizado. O teor de nutriente dissolvido foi avaliado. As técnicas de PCR e FISH foram realizadas para identificar e quantificar os micro-organismos envolvidos no ciclo do nitrogênio e bactérias potencialmente patogênicas. O levantamento sazonal revelou que a abundância bacteriana foi semelhante ao longo do ano na área rural, porém variou na região urbana. Altas concentrações de nutrientes dissolvidos na área urbana indicaram este como um sistema eutrófico. Considerando os micro-organismos nitrificantes, o gênero Nitrobacter foi encontrado, especialmente na região urbana, e pode estar atuando como a principal bactéria convertendo nitrito em nitrato nessa área. Os marcadores moleculares napA, amoA, e nfrA foram mais acumulados na área urbana, justificando o alto teor dos nutrientes metabolizados por essas enzimas. Finalmente, alta intensidade de amplicons para Enterococcus, Streptococcus, Bacteroides/Prevotella/Porphyromonas, Salmonella, S. aureus, P. aeruginosa e linhagens diarreagênicas de E. coli foram observados na área urbana. Estes resultados indicaram uma mudança na estrutura da comunidade microbiana imposta pelas ações antropogênicas. A incidência de bactérias patogênicas em ambientes aquáticos é de particular importância para a saúde pública, enfatizando a necessidade de tratamentos de esgoto para minimizar os impactos ambientais associados com a urbanização.

Benthic macroinvertebrate community structure and seasonal variation in a neotropical stream in the State of Alagoas, Brazil / Estrutura da comunidade de macroinvertebrados bentonicos e suas variacoes sazonais em um riacho neotropical no estado de Alagoas, Brasil

This paper presents a study on the macrobenthic community in the Salvia stream, a headwater stream that runs through a conserved Atlantic forest fragment in the state of Alagoas, Brazil, and identifies the environmental factors that most influence the community structure. Ten sampling sites were chosen, conducting each collection during the rainy season of 2010 and the dry season of 2011. At each site the macroinvertebrates were collected using a D net (0.250 mm mesh). Water samples were collected and taken to the laboratory to analyze Dissolved Oxygen, Conductivity, pH and Alkalinity. Water temperature, surface current speed and depth were measured at the site. Canonical Correspondence was used to analyze the effect of environmental factors on the macroinvertebrate community. All the environmental factors measured showed significant variation between seasons, showing the seasonality effects on the stream environment. Eighteen taxa were identified, with predominance of Palaemonidae (Decapoda) and Chironomidae (Diptera), respectively, during the rainy and dry season. The results showed that the macroinvertebrates were more correlated to pH, Alkalinity and Dissolved Oxygen, indicating that this ecosystem variation is mainly based on the organic matter decomposition process.

O objetivo deste estudo foi descrever a comunidade macrobentônica do riacho da Salvia, um riacho de cabeceira que atravessa um fragmento conservado de floresta remanescente de Mata Atlântica, identificando os fatores ambientais que mais influenciam a estrutura da comunidade. Dez estações de coleta foram escolhidas, onde foram realizadas coletas durante a estação chuvosa de 2010 e da estação seca de 2011. Em cada estação os macroinvertebrados foram coletados utilizando uma rede d (malha de 0,250 mm). Amostras de água foram coletadas para analisar Oxigênio Dissolvido, Condutividade, pH e Alcalinidade em laboratório. Temperatura da água, Velocidade de corrente superficial e Profundidade foram medidas em campo. Para analisar a correlação entre os fatores ambientais e a comunidade de macroinvertebrados bentônica foi utilizada a análise de Correspondência Canônica. Todos os fatores ambientais medidos mostraram variação significativa entre a estação chuvosa e seca, mostrando os efeitos da sazonalidade no ambiente do riacho. Dezoito táxons foram identificados, com Palaemonidae (Decapoda) e Chironomidae (Diptera) dominando, respectivamente, durante as estações chuvosa e seca. Os resultados mostraram que os macroinvertebrados foram mais correlacionados ao pH, Alcalinidade e Oxigênio Dissolvido, indicando que as variações neste ecossistema são baseadas principalmente nos processo de decomposição da matéria orgânica.

Diversity of Ephemeroptera (Insecta) of the Serra da Mantiqueira and Serra do Mar, southeastern Brazil / Diversidade de Ephemeroptera (Insecta) da Serra da Mantiqueira e Serra do Mar, região Sudeste do Brasil

The aim of this study was to inventory the mayfly fauna, based on nymphal and alate stages, in Serra da Mantiqueira and in Serra do Mar, São Paulo State, as well as to present information about habitats used by the genera. Nymphs were collected in several streams and mesohabitats with a Surber sampler and the winged stages with light attraction methods, entomological nets, and Malaise traps. In all, eight families and 33 genera were recorded, representing a very significant portion of the Brazilian fauna (80% of families and 49% of genera). Furthermore, it was possible to identify 11 species, of which two are new records for the state: Tricorythodes santarita Traver and Caenis reissi Malzacher. Despite the high diversity recorded, the accumulation curves presented an ascending form, indicating an increase in the number of genera with additional sampling effort. The high richness found in these areas are in agreement with the high biodiversity of the Atlantic Forest biome and the sampling effort employed, which included the use of different methods, the collection of both nymphs and winged stages, and the sampling of a large area with diverse streams and habitats.

O objetivo do trabalho foi inventariar a fauna de Ephemeroptera, com base em ninfas e estágios alados, da Serra da Mantiqueira e Serra do Mar no estado de São Paulo, bem como gerar informações sobre os hábitats utilizados pelos gêneros registrados. As ninfas foram colecionadas em diversos riachos e mesohábitats com amostrador de Surber e os alados por métodos de atração luminosa, rede entomológica e armadilha de Malaise. Considerando o esforço conjunto de todos os métodos de coleta foram registradas oito famílias e 33 gêneros, o que representa uma porção bastante significativa da fauna brasileira (80% das famílias e 49% dos gêneros). Além disso, foi possível identificar 11 espécies, das quais Tricorythodes santarita Traver e Caenis reissi Malzacher são novos registros para o estado. Apesar da alta diversidade registrada, as curva de acumulação de gêneros não atingiram a assíntota, indicando um aumento no número de gêneros com o incremento do esforço amostral. A alta riqueza encontrada nesse estudo está de acordo com a grande biodiversidade do bioma Mata Atlântica e ao esforço amostral empregado, que abrangeu o uso de diferentes métodos de coleta, coleta de ninfas e estágios alados e amostragem de uma grande área com diversos riachos e habitats.

Use of shelters and marking sites by Lontra longicaudis (Olfers, 1818) in lotic and semilotic environments / Uso de abrigos e locais de marcação por Lontra longicaudis (Olfers, 1818) em ambientes lótico e semilótico

The Neotropical otter Lontra longicaudis (Olfers, 1818) (Carnivora: Mustelidae) is a semi-aquatic species spread throughout Central and South America, except Chile. It uses cavities on the river banks or spaces amidst dense vegetation as shelter and defecates in conspicuous places as a means of territorial marking. The study was conducted between April 2008 and March 2009, aiming to compare and correlate the frequency of shelter use and marking by the otters, considering vertical vegetation cover, height, distance, disturbance degree and type of structure/substrate factors, in a lotic environment (Sapé stream, São Paulo state, Brazil) and a semi-lotic environment (Canoas I hydroelectric reservoir, Paranapanema Valley, São Paulo and Paraná states, also in Brazil). The aim was to compare and correlate the frequency of shelter use and marking by the otters, considering factors like vertical vegetation cover, height, distance, degree of disturbance and type of structure/substrate in two areas. It was evidenced that the otter's shelters show visual protection differences in each environment. Around the reservoir, the otters make greater use of areas with higher degrees of disturbance and are selective about the type of shelter structure. Along the stream, the otters favor areas with greater vegetation cover to demarcate. Our results warrant emphasis that other abiotic, biotic or density dependent factors (population number and intra or interspecific competition, for example) may be responsible for the otters' different choice of sites used for shelters and markings in the two environments but they were not identified in this study. Moreover, the different number of samples obtained in each location may have harmed the statistical analyses. However, based on the results, we were able to conclude that the species is able to adapt to the altered environment of the reservoir, using shelters and depositing markings according to the imposed environmental conditions and, whenever possible, it takes advantage of the facilitated food capture offered by environment. Nevertheless, the otters still present some dependence on areas with preserved vegetation, where they find sites with better shelter and marking conditions.

A lontra neotropical Lontra longicaudis (Olfers, 1818) (Carnivora: Mustelidae) é uma espécie semiaquática distribuída em toda a América Central e do Sul, exceto no Chile. Utiliza cavidades na margem do rio ou espaços entre a vegetação densa como abrigos e defeca em locais conspícuos como função de marcação territorial. O estudo foi realizado entre Abril de 2008 a Março de 2009 e teve como objetivo comparar e correlacionar a frequência de utilização dos abrigos e sítios de marcações das lontras com fatores de obstrução foliar vertical, altura, distância, grau de distúrbio e tipo de estrutura/substrato em um ambiente lótico (riacho Sapé, estado de São Paulo, Brasil) e um semilótico (reservatório da hidrelétrica de Canoas I, Vale do Paranapanema, estados de São Paulo e Paraná, Brasil). Constatou-se nesse estudo que os abrigos das lontras apresentaram diferenças na proteção visual em cada ambiente; que, no reservatório, utilizam mais intensamente áreas com maior grau de distúrbio e são seletivas quanto ao tipo de estrutura dos abrigos; enquanto, no riacho, as lontras demarcam preferencialmente áreas com maior obstrução vegetal. Nossos resultados permitem-nos enfatizar que outros fatores abióticos, bióticos ou denso-dependentes (número populacional e competições intra e interespecífica, por exemplo) podem ser responsáveis pela diferença na escolha das lontras pelos locais usados como abrigos e para marcações entre os dois ambientes, porém, não foram identificados nesse estudo. Além disso, a diferença no número de amostras obtidas em cada ambiente pode ter prejudicado as análises estatísticas. Conclui-se que a espécie mostra plasticidade ao ambiente alterado do reservatório, utilizando abrigos e depositando marcações conforme as condições impostas, obtendo vantagens, sempre que possível, das facilidades em captura de alimento oferecidas por este ambiente. No entanto, as lontras ainda apresentam certa dependência por áreas de vegetação preservada, onde encontram melhores condições de abrigo e marcação.

Biological monitoring of lotic ecosystems: the role of diatoms / Biomonitoramento dos ecossistemas lóticos: o papel das diatomáceas

Increasing anthropogenic influence on lotic environments as a result of civilisation has captured public interest because of the consequent problems associated with deterioration of water quality. Various biological monitoring methods that provide a direct measure of ecological integrity by using the response of biota to environmental changes have been developed to monitor the ecological status of lotic environments. Diatoms have been used extensively in this regard and this review attempts to summarise the basic concepts associated with biological monitoring using benthic diatoms. Where possible, examples from work carried out in Brazil are used.

O aumento da influência antropogênica sobre ambientes lóticos como resultado da civilização conquistou o interesse público por causa de problemas relacionados com a consequente deterioração da qualidade da água. Vários métodos de biomonitoramento que fornecem uma medida direta da integridade ecológica usando a resposta da biota a alterações ambientais têm sido desenvolvidos para monitorar o estado ecológico de ecossistemas lóticos. Diatomáceas têm sido amplamente utilizadas e esta revisão tenta resumir os conceitos básicos associados ao monitoramento biológico utilizando diatomáceas bentônicas. Sempre que possível, exemplos de trabalhos realizados no Brasil serão utilizados.