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Fish community structure is affected by a range of lake characteristics, including the cover of macrophytes that provide spawning habitats, nursery area, refuge against predators, and food. We assessed fish–macrophyte relationships at both lake and point scale using an extensive dataset from 88 Danish shallow lakes (maximum depth ≤4.5 m). At lake scale, we used mean values from fish and macrophyte community samples for all lakes, in total 88 samples. The point scale data were derived from multiple points in each lake (in total 595 samples) where both macrophytes and fish were sampled, allowing us to assess within-lake variations. We found generally negative relationships between macrophyte cover and fish abundance and biomass, which was strongest at point scale. Contrary to macrophytes, chlorophyll a showed positive relationships with fish abundance—except for perch and all fish

Disentangling the role of mechanisms driving metacommunity structure is fundamental for conservation strategies. Several studies have been done in aquatic communities; however, little is known about the factors driving oomycete communities. This research aimed to investigate beta diversity patterns and assess the role of environmental (chemical, physical, and hydrologic), spatial, and temporal (sampling months) factors in driving oomycete beta diversity in a spatial extent of 33 km from two Brazilian rivers. We took water samples in 10 sites quarterly, from August 2017 to May 2018. The partition of beta diversity into its components – species replacement and richness difference – was performed using the Jaccard dissimilarity index. Distance-based redundancy analysis and variation partitioning were used to assess the relationship between explanatory variables and beta diversity. We found that beta diversity was spatially and temporally high, and the replacement component was the main driver of the oomycete metacommunity’s beta diversity. Replacement and total beta diversity were explained mainly by spatial location and the month of sampling, while the richness difference was more associated with the environmental variables chlorophyll a and ammonia. Our findings suggest that dispersal limitation (spatial) and temporal factors are the main drivers of the total beta diversity and replacement in the oomycete metacommunity, while species sorting (environmental factor) influences the richness difference. Accordingly, that taking temporal factors into account in metacommunity studies is important to explain beta diversity patterns, especially in rivers with remarkable variability in hydrological regime and under eutrophic conditions.

Habitat structure and predation are major factors that influence the distribution of zooplankton species and functional traits. Here, we analyzed how the structure provided by macrophytes (richness, Shannon’s diversity, and biomass) and potential predation by small-bodied fishes (richness and abundance) determine the richness of species and functional traits of zooplankton, as well as the spatial dissimilarity (beta-diversity) of species and traits. Zooplankton, fish, and macrophytes were simultaneously sampled across a gradient of 30 multi-species macrophyte beds. We assessed spatial patterns of zooplankton under taxonomic and functional approaches, using linear regression models, Generalized Dissimilarity Models, a Structural Equation Model, and a Fourth-Corner Analysis. Zooplankton taxonomic beta-diversity was most represented by the turnover component and zooplankton functional beta-diversity by nestedness. Zooplankton taxonomic richness and taxonomic beta-diversity were positively related to macrophyte biomass, richness, and Shannon’s diversity, whereas zooplankton functional richness and functional beta-diversity were positively related to fish richness and abundance. Macrophyte biomass and diversity oppositely influenced fish structure, which had influence on zooplankton structure. Macrophytes also negatively influenced the zooplankton traits such as body size, reproduction type, habitat, lifespan, and predatory escape response and positively influenced the trait feeding type. Fish were negatively related to the trait body size. The spatial structure generated by macrophyte beds and fish community determined the distribution of zooplankton species and functional traits.

Here, we evaluate the role of two disparate animal groups, amphibians and odonates, in the dispersal of ciliates. We performed a 33-day outdoor experiment from July to August 2018 with four treatments: (i) a control, with only wind action; (ii) a treatment with the addition from propagules of odonates; (iii) a treatment with propagules from amphibians; and (iv) a treatment with the addition of propagules from both animals. We recorded 54 species of ciliates from 11 groups, with Peritrichia the most representative. Species richness and abundance increased markedly after the 12th day. The species composition of the ciliate species showed differences between treatments within each time period, as well as between the different treatments throughout the experiment. As expected, our results not only evidenced that the dispersal of ciliate protists was improved when mediated by biological vectors, but also demonstrated that the impact depends on the animal vector, and that the effect is even more relevant when propagules are carried by both animal vectors. Our findings support the importance of animal vectors in the dispersal and structuring of ciliates, and highlight the potential differences in the effectiveness of amphibians and odonates for the dispersal of this group.

Made available in DSpace on 2021-06-25T10:18:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Aim: Evaluating how groups of organisms vary in dispersal capability and how environmental, spatial and temporal signals vary across multiple scales is critical to elucidating metacommunity theory. We examined whether the relative contributions of environmental, spatial and hydrological factors have different effects on organismal groups with different dispersal abilities at three spatial scales, and how this knowledge contributes to our understanding of metacommunity dynamics. Location: Four major Brazilian floodplains, with the largest distance among them of 2,300 Km. Taxon: 10 aquatic organismal groups, ranging from bacterioplankton to fish. Methods: We sampled lakes connected to the main river in the low- and high-water periods of each floodplain between 2011 and 2012. Different biological groups were analysed across three hierarchical spatial scales (fine, intermediate and subcontinental) within and between floodplain systems. We applied a series of partial redundancy analyses to estimate the relative contributions of environmental factors, spatial factors and hydrological period for each biological group. Results: At the fine spatial scale, predominantly environmental factors and hydrological period structure metacommunities, although less so for microorganisms than for micro-invertebrates and macro-organisms. The relative importance of environmental factors increased at the intermediate spatial scale. At the subcontinental scale, the relative importance of spatial factors increased for all biological groups, but environmental factors remained the primary regulators of microorganisms even at the largest scale. Main conclusions: This study design allowed us to make more robust inferences about the mechanisms responsible for regulating community structure of distinct biological groups at different spatial scales. Our results suggest that biological groups displaying distinct body size likely determine the spatial extent at which environmental, spatial and hydrological processes prevail as the primary regulators of community structure. These findings are important in guiding the conservation and management of floodplain biodiversity because these systems are naturally highly heterogeneous in space and time. Universidade Estadual de Maringá (UEM) DBI/PEA/NUPÉLIA Departamento de Ecologia Instituto de Ciências Biológicas Universidade Federal de Goiás (UFG) Freshwater Centre Finnish Environment Institute (SYKE) Department of Botany University of British Columbia INPA-Instituto Nacional de Pesquisas da Amazônia Centro Universitário Ingá - Uningá/Engenharia Elétrica Departamento de Oceanografia e Limnologia – DOL Universidade Federal do Rio Grande do Norte (UFRN) Universidade de Brasília (UnB) American Museum of Natural History Department of Natural Sciences University of South Carolina Beaufort Department of Biology University of Illinois Springfield Departamento de Ecologia e Conservação - Programa de Pós-Graduação em Ecologia de Ecótono Universidade Federal de Tocantins (UFT) Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (Unesp) Universidade Federal de Mato Grosso do Sul (UFMS) Royal Belgian Institute of Natural Sciences (RBINS) OD Nature Department of Biology University of Ghent UniCesumar–PPGTL Instituto Cesumar de Ciência Tecnologia e Inovação (ICETI) Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (Unesp)

In this study, we assessed the community structure (species richness and composition) and examined concordance patterns between the active and dormant life stages of the zooplankton (Rotifera, Cladocera and Copepoda) in Southern Brazilian temporary ponds. We also examined pairwise concordance patterns in the species richness and composition between each taxonomic group. We recorded 77 species in the study area. Active communities had higher species richness and a higher number of exclusive species compared to the dormant community. Low concordance was observed in the species richness and composition of the active and dormant communities. Significant patterns were detected between similar life stages of zooplankton taxonomic groups. We found significant concordance between the species richness of dormant stages of Cladocera and Rotifera, and between the active stages of Cladocera and Copepoda. We also detected significant concordant patterns in the similarity for composition of the active stages of Cladocera and Copepoda, and of Rotifera and Copepoda. The lack of concordance between life stages indicates that the dormant communities are not adequate surrogates of the overall diversity of the zooplankton in Southern Brazilian temporary wetlands, at least under similar experimental incubation conditions. However, there is initial evidence that cladocerans and copepods can be employed as surrogates of other zooplankton groups, if the conclusions are strictly limited to active stages of the community.

Although it is widely known that dams can have large impacts on the environmental and biological characteristics of downstream rivers, there is a substantial lack of studies focusing on which ecological processes cause longitudinal changes in biological communities downstream of reservoirs. We investigated longitudinal patterns in the total beta diversity and its replacement and richness difference components for actively (fish) and passively (phytoplankton) dispersing biological groups. Our results, obtained from a 230 km sampling stretch, demonstrated the key role played by tributaries in the downstream direction from main river impoundment, which influenced local environmental conditions and beta diversity patterns of each biological group. Both replacement and richness difference contributed to high values of total beta diversity for fish (average = 0.77) and phytoplankton (average = 0.79), but their relative importance was more associated with the replacement component for both biological groups (average = 0.45 and 0.52, respectively). Moreover, we observed clear differences between fish and phytoplankton in beta diversity patterns operating at small and broad scales, as well as in the mechanisms driving each beta diversity component. Directional dispersal-related processes and environmental filtering played a major role in shaping total beta diversity and its components for fish, while temporal factors explained considerable parts of phytoplankton beta diversity. Our findings contributed to understanding of tributary-induced heterogeneity and highlight the importance of dam-free stretches of rivers for preserving the integrity of dammed river basins.

Species introduction can alter the structure and dynamics of biological communities and, therefore, understanding their feeding behavior and the effects that an exotic species can cause in the food web configuration is pivotal. We aimed to experimentally investigate the effects of the potential invasive species Kellicottia bostoniensis on different components of the microbial food web and to evaluate if the food preferences of this species change under different conditions of resource availability and interspecific interactions. We tested the hypothesis that the presence of K. bostoniensis would have direct and indirect effects on the different components of the planktonic food web. We designed three different assays (E) using prey size fractionation, being E1 composed of bacteria (HB) and picophytoplankton (PPP), E2 composed of HB, PPP and autotrophic and heterotrophic flagellates and, E3 with the whole planktonic community. Each one composed of a control in the absence of K. bostoniensis and a treatment with the presence of this species. Results showed that K. bostoniensis caused direct effects on its main food items, the heterotrophic and autotrophic flagellates, whereas no evidence of indirect effects was observed on the base components of the microbial web food, such as heterotrophic bacteria and picophytoplankton. In addition, a negative effect of the exotic rotifer on ciliates was observed. Finally, we emphasize that the impact of K. bostoniensis on aquatic ecosystem may be quite harmful, since this specie can act as a sink of matter and energy to higher trophic levels.

Made available in DSpace on 2019-10-06T15:47:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-12-01 Reptiles are highly susceptible to climate change, responding negatively to thermal and rainfall alterations mainly in relation to their reproductive processes. Based on that, we evaluated the effects of climate change on climatically suitable areas for the occurrence of snakes in the Atlantic Forest hotspot, considering the responses of distinct reproductive groups (oviparous and viviparous). We assessed the species richness and turnover patterns affected by climate change and projected the threat status of each snake species at the end of the century. We also evaluated the effectiveness of the protected areas in safeguarding the species by estimating the mean percentage overlap between snake species distribution and protected areas (PAs) network and by assessing whether such areas will gain or lose species under climate change. Our results showed greater species richness in the eastern-central portion of the Atlantic Forest at present. In general, we evidenced a drastic range contraction of the snake species under climate change. Temporal turnover tends to be high in the western and north-eastern edges of the biome, particularly for oviparous species. Our predictions indicate that 73.6% of oviparous species and 67.6% of viviparous species could lose at least half of their original range by 2080. We also found that existing protected areas of the Atlantic Forest Hotspot have a very limited capacity to safeguard snakes at the current time, maintaining the precarious protection in the future, with the majority of them predicted to lose species at the end of this century. Although oviparous and viviparous snakes have been designated to be dramatically impacted, our study suggests a greater fragility of the former in the face of climate change. We advocated that the creation of new protected areas and/or the redesign of the existing network to harbour regions that maximize the snake species occupancy in the face of future warming scenarios are crucial measures for the conservation of this group. Programa de Pós-graduação em Ecologia de Ambientes Aquáticos Continentais (PEA) Universidade Estadual de Maringá Maringá Laboratório de Herpetologia e Comportamento Animal Universidade Federal de Goiás Programa de Pós-Graduação em Biologia Comparada (PGB) Universidade Estadual de Maringá Laboratório de Macroecologia Universidade Federal de Goiás Regional de Jataí Departamento de Zoologia Instituto de Biociências Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP) Departamento de Ecologia Instituto de Ciências Biológicas Universidade Federal de Goiás Departamento de Zoologia Instituto de Biociências Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP)

In floodplain lakes, precipitation events shape the environmental heterogeneity and the occurrence of species and functional traits. However, the importance of each biotic and abiotic factor on structuring communities might depend on the local environmental conditions and the identity of such communities. We investigated through Permutational analyses of variance and functional β-diversity components, the effects of neutral and extreme events of precipitation on environmental heterogeneity and distribution of zooplankton functional traits in floodplain lakes. We also examined through distance-based redundancy analysis and fourth-corner analysis, how different variables (physical–chemical, food availability, predation, and temporal dynamics) structure the distribution of zooplankton functional traits and which traits were related to these variables. We used data from six lakes of the Upper Parana River floodplain over 19 years. Environmental heterogeneity and β-diversity were higher during El Nino and lower during La Nina (extreme rainy and extremely dry season, respectively). Physical–chemical were the variables that most explained zooplankton β-diversity during all seasons and predation during both extreme seasons (La Nina and El Nino). We observed a set of multiple biotic and abiotic factors causing complex effects on zooplankton functional diversity. The homogenization of traits—observed during extreme dry seasons—can lead to losses in ecosystem functions and services if these events continue to be more frequent and intense. We reaffirm the importance of natural flood caused by the rainy seasons to maintain high biotic and abiotic heterogeneity and ecosystem processes.

The increasing amount of plastic particles introduced into continental aquatic environments has drawn the attention of researchers around the globe. These particles can be assimilated by a wide range of aquatic organisms, from microorganisms to fish, causing detrimental effects on trophic webs. Using an experimental approach, we investigated the effect of microplastic particles of different sizes on the planktonic trophic chain by sampling natural plankton communities from a lake located in the Upper Paraná River floodplain, Brazil. Zooplankton samples were collected at the beginning of the experiment and after 36 h of incubation. Microplastic particles (MP) samples were taken every 12 h. The effect of MP particle consumption from the control and treatment groups indicates significant effects by all plankton size fractions (p0.05). We demonstrated that the presence of MP particles can significantly affect the trophic web, furthermore, we detected the effect of higher consumption effect of smaller size MP particles. This study suggest that the largest MP consumption effects come from the lower trophic levels of the trophic chain, such as protists. The competitive effect of large predators is a crucial factor in controlling the abundance of populations, and although they did not directly consume MP particles, they ingest them indirectly through prey capable of absorbing these compounds in the environment. Our findings warn that MP particles enter the food webs of tropical regions when exposed to these pollutants, and that the presence of these particles should not be neglected when studying freshwater ecosystems.

We aimed to investigate spatial and temporal scales, abundance, and factors that structure the communities of protozoans in a tropical urban stream. Methods: Samples of water for analysis of biological communities (testate amoebae, ciliates and bacteria) and limnological variables were taken in the Mandacaru stream located in the Conservation Unit of Parque do Cinquentenário, in the city of Maringá, Paraná State, Brazil, in two hydrological periods (dry and rainy). We calculated the Water Quality Index (WQI) composed by nine parameters of water quality (dissolved oxygen, thermotolerant coliforms, pH, BOD, water temperature, total nitrogen, total phosphorous, turbidity, and total solids), Trophic State Index (TSI) for phosphorous and we used a Redundancy Analysis (RDA) to verify the influence of environmental variables in the protozoan community. Results: The WQI showed that water quality was considered good in some points and considered bad in other points. The TSI for phosphorus classified the stream as mesotrophic in the majority of sampled sites points (mean between 53.09 and 58.35). We identified 19 taxa of testate amoebae, belonging to six families, being Difflugiidae, Centropyxidae, and Arcellidae those with more species and 71 infrageneric taxa of ciliates, distributed in 12 orders being Peniculida the most representative order, followed by Euplotida. According to RDA analysis, samples of the dry period were characterized by higher values of bacteria density and concentrations of chlorophyll-a, total phosphorous, and total nitrogen. Ciliates and testate amoebae presented higher abundance values in some of the months characterized by higher precipitation and in conditions of higher system productivity. Conclusion: we may conclude that the Mandacaru stream, although strongly influenced by anthropic action, still presents an acceptable water quality. Lastly, we emphasize that protists abundance was strongly influenced by system productivity. This was evidenced by elevated protozoan densities where there was higher primary and bacterial productivity. Thus, these organisms must be considered in studies that aim at the identification of organisms that may indicate anthropic impacts and environmental quality. Resumo O objetivo foi investigar, em escalas espacial e temporal, a abundância das comunidades de protozoários bem como os fatores intervenientes na estruturação das mesmas em um córrego urbano. Métodos: Amostras de água para análise de comunidades biológicas (amebas testáceas, ciliados e bactérias) e para análise de variáveis limnológicas foram tomadas no córrego Mandacaru localizado na Unidade de Conservação do Parque do Cinquentenário, na cidade de Maringá, Paraná State, Brasil, em dois períodos hidrológicos (seco e chuvoso). Calculamos o Índice de Qualidade de Água (IQA), o Índice de Estado Trófico (ETI) para fósforo e utilizamos uma Análise de Redundância (RDA) para verificar a influência de variáveis ambientais na comunidade de protozoários. Resultados: O IQA mostrou que a qualidade da água foi considerada boa em alguns pontos e considerada ruim em outros pontos, e o ETI para o fósforo classificou o córrego como mesotrófico na maioria dos locais amostrados (média entre 53,09 e 58,35). Foram identificados 19 táxons de amebas testáceas, pertencentes a seis famílias, sendo Difflugiidae, Centropyxidae e Arcellidae as mais especiosas, e 71 táxons de ciliados, distribuídos em 12 ordens, sendo Peniculida a ordem mais representativa, seguida por Euplotida. De acordo com a análise RDA, amostras do período seco foram caracterizadas por maiores valores de densidade bacteriana e concentrações de clorofila-a, fósforo total e nitrogênio total. As amebas testáceas e os ciliados apresentaram valores de abundância maiores em alguns dos meses caracterizados por maior precipitação e em condições de maior produtividade do sistema. Podemos concluir que o córrego Mandacaru, embora fortemente influenciado pela ação antrópica, ainda apresenta uma qualidade de água aceitável. Por fim, enfatizamos que a abundância de protistas foi fortemente influenciada pela produtividade do sistema. Isto foi evidenciado pelas elevadas densidades de protozoários onde houve maior produtividade primária e bacteriana. Assim, esses protistas devem ser considerados em estudos que visem à identificação de organismos que possam indicar impactos antrópicos e qualidade ambiental.

The increasing number of COVID-19 cases threatens human life and requires retainment actions that control the spread of the virus in the absence of effective medical therapy or a reliable vaccine. There is a general consensus that the most efficient health protocol in the actual state is to disrupt the infection chain through social distancing, although economic interests stand against closing non-essential activities and poses a debatable tradeoff. In this study, we used an individual-based age-structured network model to assess the effective roles of different healthcare protocols such as the use of personal protection equipment and social distancing at neighbor- and city-level scales. Using as much as empirical data available in the literature, we calibrated a city model and simulated low, medium, and high parameters representing these protocols. Our results revealed that the model was more sensitive to changes in the parameter representing the rate of contact among people from different neighborhoods, which defends the social distancing at the city-level as the most effective protocol for the control of the disease outbreak. Another important identified parameter represented the use of individual equipment such as masks, face shields, and hand sanitizers like alcohol-based solutions and antiseptic products. Interestingly, our simulations suggest that some periodical activities such as going to the supermarket, gas station, and pharmacy would have little contribution to the SARS-CoV-2 spread once performed within the same neighborhood. As we can see nowadays, there is an inevitable context-dependency and economic pressure on the level of social distancing recommendations, and we reinforce that every decision must be a welfare-oriented science-based decision.

The biodiversity and biogeography of protists inhabiting many ecosystems have been intensely studied using different sequencing approaches, but tropical ecosystems are relatively under-studied. Here, we sampled planktonic waters from 32 lakes associated with four different river-floodplains systems in Brazil, and sequenced the DNA using a metabarcoding approach with general eukaryotic primers. The lakes were dominated by the largely free-living Discoba (mostly the Euglenida), Ciliophora, and Ochrophyta. There was low community similarity between lakes even within the same river-floodplain. The protists inhabiting these floodplain systems comprise part of the large and relatively undiscovered diversity in the tropics.

Inland aquatic ecosystems play a critical role in the global carbon cycle, processing a great fraction of the organic matter coming from terrestrial ecosystems, and the microbial food web is crucial in this process. Thus, we aimed to evaluate whether the food resource of planktonic protozoa comes mainly from small primary producers or heterotrophic bacteria in tropical shallows lakes, assuming the hypothesis that, in general, picocyanobacteria would be the main food resource for protists. We also expected that the autotrophic fraction would be mainly related to protists at the surface of the environments, while the heterotrophic fraction would be more important at the lower strata of the water column. We performed size-fractionation experiments to evaluate the effects of predation of protists on heterotrophic bacteria and picocyanobacteria. We also sampled planktonic organisms at the subsurface and bottom of 20 lakes in a Neotropical floodplain. We found an herbivory preference of heterotrophic flagellates, while ciliates seem to exert a stronger impact on heterotrophic bacteria. We also found no relationship between heterotrophic bacteria and protists in the field data, whereas positive relationships between picocyanobacteria and protists were observed in environments where there was sunlight. Thus, both heterotrophic bacteria and picocyanobacteria were important components in the food webs of tropical shallow lakes. Moreover, the trophic cascade caused by zooplankton predation suggests that protists are efficient in transferring the energy from the base of microbial food webs to higher trophic levels.

The invasion success of non-native species depends on a variety of factors, and abiotic characteristics of invasive ranges and their native populations can offer resistance to non-native species establishment. Reservoirs, compared to natural lakes, can facilitate submerged macrophyte invasion because they provide favorable abiotic conditions to macrophyte establishment and development. However, previous colonization of native species can hamper the development of invasive ones through priority effects. In this investigation we used large data-set obtained in the Itaipu Reservoir (Brazil/Paraguay) to assess the relationship between the abundance of the native submerged macrophyte Egeria najas and of the invasive Hydrilla verticillata and water level, littoral slope and Secchi disk depth. We also investigated how the concomitant and previous abundance of both macrophytes correlates. A Bayesian modeling was applied, controlling the effect of spatial-temporal autocorrelation. Our results indicate an important role of water transparency, littoral slope and water level oscillations in a short period of time (30 days) for the temporal dynamics of these species’ abundances. Fluctuations of water levels and littoral slope affected H. verticillata to a greater extent than E. najas. In addition, the abundance of each species was related with its own abundance in previous samplings, highlighting the possible importance of habitat suitability, vegetative propagule pressure and resistance structures for population recovery. In low abundances, there was a possible facilitation between both species, while high abundances probably increased competition. The great importance of water level oscillations on these species’ abundances indicate that this strategy can be used as management tool.

Many plants may accumulate rainwater, forming phytotelmata, aquatic microhabitats inhabited by various organisms. The aim of this study was to conduct an inventory of heterotrophic flagellates associated with phytotelmata of the bromeliad Aechmea distichantha Lem., found in rocky cliffs on the Upper Paraná River. The bromeliads were removed manually from the rocky wall, the water was removed and cultures of organisms of each plant were mounted in Petri dishes. Sixteen species of heterotrophic flagellate were recorded, drawn and described, among them one species belonging to the Amorpha Domain and 15 species to the Diaphoretiches Domain. The groups with most species were Euglenida and Kinetoplastea. The low diversity of heterotrophic flagellates recorded in this study, compared to the plankton of lakes and reservoirs, is probably related to the fact that phytotelmata are habitats with extreme environmental conditions, thus selecting organisms tolerant to these environments. Resumo Em sua superfície externa, muitas plantas podem acumular água da chuva formando fitotelmata, ou seja, micro-habitat aquáticos colonizados por diversos organismos, entre eles, os flagelados protistas. Fez-se um inventário de flagelados heterotróficos associados ao fitotelmata da bromélia Aechmea distichantha Lem., encontrada em paredões rochosos em um trecho da bacia do alto rio Paraná. As bromélias foram retiradas manualmente de paredão rochoso e, em laboratório, a água foi retirada dos tanques de cada planta, e foram montadas culturas dos organismos em placas de Petri. Os flagelados heterotróficos foram, então, observados in vivo sob microscópio óptico Olympus BX51, com sistema de contraste de interferência diferencial (DIC) acoplado. Dezesseis espécies flagelados heterotróficos foram registradas, desenhadas e descritas, sendo uma espécie pertencente ao Domínio Amorpha e 15 espécies ao Domínio Diaphoretiches. Os grupos mais especiosos foram Euglenida e Kinetoplastea. A diversidade relativamente reduzida de flagelados heterotróficos, quando comparada ao plâncton de lagos e reservatórios, pode estar relacionada ao fato de os fitotelmata serem habitats limitados, com condições ambientais extremas, selecionando, assim, organismos tolerantes a esses ambientes.

Extreme events can cause species substitution or biodiversity losses. In floodplains, flood and drought phases are considered disturbances when their amplitude or intensity are atypical. These unpredictable events can affect the structure of aquatic communities. In this context, we evaluated the response of the zooplankton community to two extreme droughts that occurred from 2001−2002 and 2014−2016. We assessed species richness and composition on three occasions: before extreme drought (phase 1); during the phase after extreme drought (phase 2) characterized by floods, and lastly, after flood (phase 3), when the fluctuations in water levels in the lowlands stabilized. We hypothesized that (i) zooplankton composition in the lake is distinct in the phases before extreme drought and flood, as the extreme drought event causes changes in the community structure and (ii) after the flood (phase 3), the composition of species in the lake would be more similar to the phase 1, with a large number of species shared in these. Contrary to what we expected, similarity in the species composition of the lake was greater between the phase 1 and phase 2, which may indicate the resilience capacity of the community, through specialized adaptations capable of tolerating extreme. The lowest similarity was observed between the phase 1 and phase 3 and this difference may be a consequence of the dilution effect of the community in the flood (phase 2). Our results suggest that the community structure in the lake can be considered more resilient to extreme drought. We also highlight the importance of the hydrological dynamics of a floodplain for the structure of communities, considering atypical droughts in periods of different climatic events.

Functional diversity approaches have been an efficient tool in gaining a better understanding of how environmental conditions selected species in a given environment and how they share resources, linking ecological processes to biodiversity patterns. Although most of the protist ciliates are not highly specialized, functional feeding groups with species which ingest similar food can be identified. Thus, this study aimed to compare the abundance of different Functional Feeding Groups (FFG) of ciliates in environments with different hydrodynamic conditions (lotic and lentic) in different hydrological periods (high and low water) in a neotropical flood plain. The samples for analysis of the community of ciliates were taken in March and September of 2010 and 2011, at the subsurface of 12 different hydrodynamic environments. The results of an RDA showed a spatial and temporal segregation of the sampling units, based on the abundance and occurrence of the FFG. In addition, a clear influence of food resources on the structuring of functional ciliate guilds was evidenced. Thus, there were both temporal (hydrological periods) and spatial (different hydrodynamic environments) differences in the distribution of the FFG, with a clear separation of the FFGs between the years studied. In summary, the results of the categorization of species of ciliates in FFG responded satisfactorily suggesting fluctuations in different food resources, which reinforces the idea that the grouping of species by functional characteristics can be a good indicator of the responses of organisms to environmental fluctuations.

The aim of this study was to investigate the spatial and temporal patterns in species composition of ciliates, in rural streams, affected by agricultural activities, and urban streams, impacted by domestic wastewater. Samplings were taken in two different periods of the year, in the headwater, middle and mouth stretch of ten streams. We recorded 143 species of ciliates, distributed in 14 groups, standing out Hymenostomatia, Peritrichia and Hypotrichia. Our results showed significant spatial (between rural and urban streams) and, especially, temporal differences (between winter and summer periods) in the ciliates taxonomic composition. Such differences seem to be not related to the organic load that was quite similar among streams and periods sampled. Rather, the changes in ciliates composition are probably driving mainly by other enviromental variables such as resources, determined by the spatial diferences in light availability, and flow water velocity and discharge, which present high temporal dissimilarity.

Dispersal potential of organisms is directly related to the hydrological connectivity among habitats. We investigated if the relative role of the environmental and spatial components in structuring the heterotrophic flagellates depends on the degree of hydrological connectivity. Samplings were performed in aquatic environments of the Parana River floodplain, which differ in their degree of connectivity: lotic environments, connected lakes and isolated lakes (temporarily connected to the main river only during floods). We expect that communities in isolated lakes would be more subject to dispersal limitation, while in connected lakes and lotic environments the communities would be regulated mainly by environmental variables (species sorting). We sampled in the pelagic region of 23 environments during the low water period in 2014. The results of pRDA revealed that the contributions of environmental and spatial factors differed between the types of environments. The greater contribution of the environmental variables in structuring the flagellates metacommunity, regardless of the type of environment, may be related to the elevated dispersal capacity of microorganisms. The spatial component was also significant in the isolated lakes. Our results support the idea that microorganism communities are mainly structured by environmental factors, although the spatial component seems important when lakes are isolated.

While the biodiversity and biogeography of protists inhabiting many ecosystems have been intensely studied using different sequencing approaches, tropical ecosystems are relatively under-studied. Here we sampled planktonic waters from 32 lakes associated with four different river-floodplains systems in Brazil, and sequenced the DNA using a metabarcoding approach with general eukaryotic primers. The lakes were dominated by the largely free-living Discoba (mostly the Euglenida) and Ciliophora unlike previously sampled Neotropical environments, bu the community similarities between samples were likewise low. These protists inhabiting these floodplains potentially form part of the large diversity of unknown diversity in the tropics.

Metacommunity studies using the deconstruction approach based on biological traits have received a great deal of attention in recent years as they often better describe characteristics of the species that reflect adaptations to a specific environment. This approach has not yet been used for ostracods, which are nevertheless highly diverse crustaceans and abundant in continental aquatic environments. Here, we investigate the influence of environmental and spatial factors on the metacommunity structure of periphytic ostracods in 27 tropical floodplain lakes in the Upper Parana River floodplain (Brazil). An analysis of variance partitioning was used to estimate the relative importance of these factors (environmental and spatial) on both the entire community as well as after its deconstruction according to the biological traits (size and locomotion mode). Ostracods, regardless of body size, are good dispersers at regional scales. In addition, as expected, swimming ostracods were better dispersers at local scales than non-swimmers, which were influenced mainly by the diversity of aquatic macrophytes. Environmental factors (species sorting mechanism) seem important in structuring the entire ostracods metacommunity, as well as for most categories of biological traits. The unexplained variability remained high showing that other variables, not measured here, must be important. The analysis based on deconstruction, when compared to the analysis based on the metacommunity as a whole, contributed to a better assessment of ostracod metacommunity structuring.

Aim: We aimed to evaluate the variation in planktonic ciliate species composition in different strata of the Guaraná Lake, encompassing high and low water periods, at the Upper Paraná River floodplain. Methods Samplings were collected monthly between March 2007 and February 2008, from the epilimnion, metalimnion and hypolimnion. Ciliates samples were filtered using a plankton net of 10µm mesh size and identified in vivo under an optical microscope. Results Among 112 species identified, 13 were found exclusively during the high water periods and 39 during the low water period. Results of nonparametric extrapolation indices evidenced that the observed richness represented between 70% and 90% of the estimated richness. Regarding the variation in species composition, Beta1 index showed that the alteration in composition between strata during the low water period was slightly greater than that registered during high waters. Cluster analysis evidenced a higher dissimilarity in ciliate species composition between periods than among the different strata. The greatest variation in species composition was verified during the distinct hydrological periods, whereas no significant differences were observed for the different strata analysed. Conclusions We found that in the pelagic compartment, ciliate species composition changed significantly between hydrological periods, and a higher similarity in species composition among strata was observed during the high water period. Therefore, alterations in the vertical distribution seem to be related to the homogenizing effect of the floods in the water column stability.

Aim : We investigated the spatial and temporal patterns of abundance and diversity of planktonic ciliate community, in the last undammed stretch of the Upper Parana River, Brazil. Methods : In order to reach this result, seven field campaigns were performed over two years. Plankton samples were collected from 10 transects through this stretch of the river (230 Km), near the banks and on the center, as well on seven of its tributaries. Results : 95 ciliates species were identified, among which the peritrichs were the most abundant while the order Hymenostomatida was the most specious group. We recorded a remarkable increase in abundance and species richness along the river, especially in the rainy period. Moreover, in this period we found an increase in the beta-diversity along the river, which consists in a remarkable distinction among the low, middle and high stretch of the river. In this way, continuous changes in the community structure of planktonic ciliates were evidenced, highlighting the importance of the precipitation and tributaries in the maintenance of the highest regional diversity in the studied area. Conclusion : Our results strongly suggest the requirement for conservation actions with the purpose to maintain those tributaries undammed, in order to avoid biotic homogenization processes and the consequent reduction of aquatic biodiversity in this important tropical ecosystem.

The objective of this work was to investigate the patterns of diversity and abundance of ciliates protozoa community in three tropical urban streams and verify which species can be considered bioindicators of water quality. In each stream, three regions (headwater, middle and mouth) were sampled in two years, in the rainy and dry seasons. The abiotic factors (dissolved oxygen, pH, temperature, turbidity, width, depth, flow and conductivity) and biotic factors (total coliforms, bacterioplankton, chlorophyll and flagellates) were analyzed using appropriate methods and ciliates were identified and counted through specialized literature. We identified 84 species distributed into 24 orders. Peniculida was the most representative order followed by Prorodontida. The RDA scores showed a spatial difference between streams. On the other hand, regarding the temporal variation, there was no separation of the sampled data. The Indval analysis showed ten species indicators, such as Coleps hirtus, Euplotes moebiusi and Tintinidium pusillum. The Cluster analysis per stream versus period showed a greater distinction of the streams in the dry season. On the other hand, a low similarity was observed between sections within the same stream. In summary, the results indicated that the ciliates can be used as important tools as bioindicators in lotic environments affected by different degrees of pollution, due to the fact that they have short life cycle, allowing the detection of impacts on a small time scale, as well as by having direct answers to environmental changes and high sensitivity to contaminants. Resumo O objetivo deste trabalho foi investigar os padrões de diversidade e abundância da comunidade de protozoários ciliados em três córregos urbanos tropicais, bem como verificar quais espécies podem ser consideradas bioindicadoras da qualidade da água. Em cada córrego foram amostradas três regiões (cabeceira, intermediária e foz) em dois anos, nas estações chuvosa e seca. Os fatores abióticos (oxigênio dissolvido, pH, temperatura, turbidez, largura, profundidade, fluxo e condutividade) e fatores bióticos (coliformes totais, bacterioplâncton, clorofila e flagelados) foram analisados por metodologia específica e os ciliados foram contados e identificados por meio de literatura especializada. Foram identificadas 84 espécies distribuídas em 24 ordens. Peniculida foi a ordem mais representativa, seguida por Prorodontida. Os escores da RDA mostraram uma diferença espacial entre os córregos. Por outro lado, em relação à variação temporal, não houve separação entre os dados amostrados. A análise Indval mostrou dez espécies indicadoras, como Coleps hirtus, Euplotes moebiusi e Tintinidium pusillum. A análise de Cluster realizada por riacho versus período evidenciou uma maior distinção dos córregos no período seco. Por outro lado, foi observada uma baixa similaridade entre os locais dentro do mesmo córrego. Em síntese, os resultados indicaram que os ciliados podem ser utilizados como ferramentas importantes como bioindicadores em ambientes lóticos afetados por diferentes graus de poluição, devido ao fato de apresentarem um curto ciclo de vida, permitindo a detecção de impactos em uma pequena escala de tempo, bem como por apresentarem respostas diretas às mudanças ambientais e alta sensibilidade a contaminantes.

Anthropogenic disturbances change the trophic structure of streams, ultimately affecting ecosystem functioning. We investigated the effects of human disturbances, mainly organic pollution, on ciliate functional feeding groups (FFG) in 10 tropical streams near agricultural and urban habitats, in the dry and rainy seasons. We hypothesised that the organic pollution would affect the ciliate composition and that the richness and abundance of ciliate FFG would be associated with different disturbances, such that an increase in the load of organic matter would result in an increase in the percentage of bacterivores ciliates, while streams with low organic matter concentration and wide canopy openness will determine a higher contribution of algivorous ciliates. Our results corroborate our hypothesis of an increased development of bacterivorous ciliates with increasing organic pollution, but only in the abundance of this FFG. Also, algivorous ciliates were found to be related to riparian vegetation clearing. Thus, ciliate FFG accurately reflected different anthropogenic disturbances, revealing a change in the trophic structure of the streams. In addition, we found that organic pollution can lead to both taxonomic and functional homogenization of the ciliate community, which implies serious consequences for ecosystem functioning.

Recent studies reported comparatively lower heterotrophic bacteria (HB) abundances in tropical regions, indicating that factors involved in bacterial losses could be more relevant in the tropics. Heterotrophic nanoflagellates (HNF) are considered the main predators of HB in aquatic ecosystems, and one should expect higher abundances in the tropics because of differences in the food web configuration (absence of large daphnids). However, there are no comprehensive studies comparing HB and HNF abundances in a latitudinal gradient. We hypothesized that HB abundance would be lower in the tropics because HNF abundance would be higher, resulting in a tighter HNF-HB coupling. To test this hypothesis, we compiled a large dataset of HB and HNF abundances from tropical and temperate freshwater environments. We found that both HB and HNF abundances were lower in the tropical region, and that HNF-HB coupling does not differ between temperate and tropical regions. The lower HNF abundance and lack of coupling may be explained by a strong top-down control on HNF and/or their herbivory preference. Besides, no relationship was found between bacterial specific growth rate and either chlorophyll-a and HB abundance, indicating that bacterial losses may have an important role in tropical freshwaters. Thus, we found that HNF is likely not the main controllers of HB abundance, and that grazing by ciliates and cladocerans, together with the physiological effects of higher temperatures, may explain the high bacterial loss rates in the tropics. Fil: Segovia, Bianca T.. Universidade Estadual de Maringá; Brasil Fil: Domingues, Carolina D.. Universidade Federal do Rio de Janeiro; Brasil Fil: Meira, Bianca R.. Universidade Estadual de Maringá; Brasil Fil: Lansac Toha, Fernando M.. Universidade Estadual de Maringá; Brasil Fil: Fermani, Paulina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; Argentina Fil: Unrein, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; Argentina Fil: Lobão, Lúcia M.. Universidade Federal de Juiz de Fora; Brasil Fil: Roland, Fabio. Universidade Federal de Juiz de Fora; Brasil Fil: Velho, Luiz F. M.. Universidade Estadual de Maringá; Brasil Fil: Preto de Morais Sarmento, Hugo Miguel. Universidade Federal do São Carlos; Brasil

Background: In this paper, we verified the changes in species composition of the ciliate community inhabiting phytotelmata of tank bromeliads in response to seasonality (rainfall). Plants were located at several heights of a great rocky wall on the left bank of the Parana River, southern Brazil. We also assessed if the heights of the plants in relation to the river influence the ciliate species composition. Thus, samplings were performed in the dry and rainy seasons, in three layers of the rock walls (lower, middle, and upper), with a total of 72 samples in both periods. Results: A relative high number of species and a predominance of hymenostomatids were observed in the sampled plants. Among the recorded species, about 35% occurred exclusively in the dry season. The detrended correspondence analysis demonstrated that the ciliate community changed substantially due to rainfall. However, there was no distinctness in species composition among the strata. In contrast to expectations, the number of species recorded in the dry season was greater than that recorded in the rainy season, refuting the hypothesis that the precipitation volume favors an increase in the number of species. Conclusions: The rainfall is, undoubtedly, the main factor structuring the community and determining the ciliate species composition in the phytotelmata of the bromeliads. We found that the closeness of the plants with the river is also an important factor for the structuration of the community, due to the dispersion of organisms from the river to the tanks. The occurrence and predominance of planktonic species in the plants at the lower stratum and soil species at the higher stratum indicates a great influence of the neighboring environments on the ciliate community inhabiting the phytotelmata.

This study examined temporal and spatial (vertical) variations of composition, richness and abundance of the planktonic ciliates community in an urban and eutrophic lake, as well as identified the limnological factors involved in determining the patterns observed. To this end, samples of ciliates and measures of limnological variables were taken at different depths and hydrological periods. 35 ciliate species were identified, among which 14 species occurred in all periods and strata, being Prostomatida the most specious, followed by Gymnostomatida, Oligotrichida, Peritrichida, and Scuticociliatida. The patterns found for composition, abundance and species richness evidenced a vertical and temporal variation of these attributes. However, in general the composition and species richness have varied more along the vertical gradient than between periods, whereas for the abundance, only temporal differences could be detected. Results observed herein indicated that benthic species seem to be mainly influenced by the amount of organic matter, phosphorus and ammonia, while planktonic ones, abundant at the surface, were mainly associated with higher dissolved oxygen concentrations. In this way, seasonal and vertical variations of limnological characteristics were decisive for the patterns of occurrence and abundance of ciliate species.