Composição de amebas testáceas (Amoebozoa: Rhizopoda) associadas à rizosfera de Eichhornia crassipes (Martius) Solomons (Pontederiaceae) no Rio Cachoeira, Bahia, Brasil: novos registros para o Nordeste

Studies on microorganisms associated or adhered to aquatic macrophytes are scarce. Due to the important role that testate amoebae (Amoebozoa: Rhizopoda) have in the metabolism of inland waters and the scarcity of information about diversity of this group, the objective of this study was to characterize the composition of testate amoebae associated with Eichhornia crassipes stands in this river, in two hydrologic periods. This work registered 115 taxa of testate amoebae associated to the rizosphere of E. crassipes, belonging to 10 families, 14 genera, 96 species and 19 varieties, distributed in Difflugiidae (42 taxa), Arcellidae (21 taxa), Centropyxidae (14), Euglyphidae, Lesquereusiidae (11 each), Cryptodifflugiidae (7), Trigonopyxidae, Trinematiidae (3 each), Hyalospheniidae (2), and Cyphoderiidae (1). The high richness of testate amoebae are registered in the flood periods river. However, high similarity was observed within the assemblage composition in two hydrological periods. This work includes 84 new registers of tecamebas for the Northeast of Brazil, thus totalizing 137 taxa for this region, and for Bahia State it was recorded 112 new occurrences, what demonstrates the necessity to increase the efforts of collection in the state.Estudos envolvendo microorganismos associados e/ou aderidos a macrófitas aquáticas são escassos. Assim, considerando a importância das amebas testáceas (Amoebozoa: Rhizopoda) no metabolismo de ambientes aquáticos e a escassez de informações sobre a diversidade das tecamebas, este trabalho teve como objetivo determinar a composição das amebas testáceas associadas a estandes de Eichhornia crassipes no Rio Cachoeira, em dois períodos hidrológicos. Foram inventariados 115 taxa de amebas testáceas associadas à rizosfera de E. crassipes, pertencentes a 10 famílias, 14 gêneros, 96 espécies e 19 variedades, distribuídos nas seguintes famílias: Difflugiidae (42 taxa), Arcellidae (21), Centropyxidae (14), Euglyphidae, Lesquereusiidae (11 cada), Cryptodifflugiidae (7), Trigonopyxidae, Trinematiidae (3 cada), Hyalospheniidae (2) e Cyphoderiidae (1). As maiores riquezas de espécies foram registradas no período de maior vazão do rio. Entretanto, elevadas similaridades na composição de espécies foram encontradas entre os períodos hidrológicos. Este trabalho inclui 84 novos registros de tecamebas para o Nordeste do Brasil, totalizando 137 taxa para esta região, sendo que para a Bahia são registradas 112 novas ocorrências, demonstrando-se a necessidade de aumentar os esforços de coleta no estado

A Global eDNA Comparison of Freshwater Bacterioplankton Assemblages Focusing on Large-River Floodplain Lakes of Brazil

With its network of lotic and lentic habitats that shift during changes in seasonal connection, the tropical and subtropical large-river systems represent possibly the most dynamic of all aquatic environments. Pelagic water samples were collected from Brazilian floodplain lakes (total n = 58) in four floodpulsed systems (Amazon [n = 21], Araguaia [n = 14], Paraná [n = 15], and Pantanal [n = 8]) in 2011–2012 and sequenced via 454 for bacterial environmental DNA using 16S amplicons; additional abiotic field and laboratory measurements were collected for the assayed lakes.We report here a global comparison of the bacterioplankton makeup of freshwater systems, focusing on a comparison of Brazilian lakes with similar freshwater systems across the globe. The results indicate a surprising similarity at higher taxonomic levels of the bacterioplankton in Brazilian freshwater with global sites. However, substantial novel diversity at the family level was also observed for the Brazilian freshwater systems. Brazilian freshwater bacterioplankton richness was relatively average globally. Ordination results indicate that Brazilian bacterioplankton composition is unique from other areas of the globe. Using Brazil-only ordinations, floodplain system differentiation most strongly correlated with dissolved oxygen, pH, and phosphate. Our data on Brazilian freshwater systems in combination with analysis of a collection of freshwater environmental samples from across the globe offers the first regional picture of bacterioplankton diversity in these important freshwater systems

Diversity and succession of pelagic microorganism communities in a newly restored Illinois River floodplain lake

While the success of restoration efforts frequently depends on reconstructing ecological communities, time series observations of community structure over the course of restoration are rare. Here, frequent sampling of bacterioplankton, phytoplankton, planktonic protozoa (ciliates and testaceans), and zooplankton was done along with measurements of select physical and chemical parameters during the first year of ecological restoration of Thompson Lake (TL), an Illinois River floodplain lake not connected to the river. The primary objective was to describe the microbial composition, diversity, and seasonal dynamics in TL and compare these results to similar measurements made in a nearby reference lake, river flood-pulsed Lake Chautauqua (LC). Strong seasonal patterns in bacterioplankton diversity were observed for both lakes. While TL phytoplankton diversity was lower and blooms more erratic than in LC, ciliate richness and abundance patterns were similar in both lakes. Rotifers and microcrustaceans were about 5× more abundant in TL than LC, with copepods and cladocerans exhibiting a fall abundance peak only in TL. When compared to temporal patterns of planktonic microorganisms in the reference lake (LC), the microbial dynamics in a lake recovering from decades of agriculture and drainage (TL) reflect the instability associated with early stages of ecological restoration.Ope

Trophic downgrading decreases species asynchrony and community stability regardless of climate warming

Theory and some evidence suggest that biodiversity promotes stability. However, evidence of how trophic interactions and environmental changes modulate this relationship in multitrophic communities is lacking. Given the current scenario of biodiversity loss and climate changes, where top predators are disproportionately more affected, filling these knowledge gaps is crucial. We simulated climate warming and top predator loss in natural microcosms to investigate their direct and indirect effects on temporal stability of microbial communities and the role of underlying stabilising mechanisms. Community stability was insensitive to warming, but indirectly decreased due to top predator loss via increased mesopredator abundance and consequent reduction of species asynchrony and species stability. The magnitude of destabilising effects differed among trophic levels, being disproportionally higher at lower trophic levels (e.g. producers). Our study unravels major patterns and causal mechanisms by which trophic downgrading destabilises large food webs, regardless of climate warming scenarios

Effects of warming on the structure of aquatic communities in tropical bromeliad microecosystems

Abstract Freshwaters are among the most vulnerable ecosystems to climate warming, with projected temperature increases over the coming decades leading to significant losses of aquatic biodiversity. Experimental studies that directly warm entire natural ecosystems in the tropics are needed, for understanding the disturbances on aquatic communities. Therefore, we conducted an experiment to test the impacts of predicted future warming on density, alpha diversity, and beta diversity of freshwater aquatic communities, inhabiting natural microecosystems—Neotropical tank bromeliads. Aquatic communities within the tanks bromeliads were experimentally exposed to warming, with temperatures ranging from 23.58 to 31.72°C. Linear regression analysis was used to test the impacts of warming. Next, distance‐based redundancy analysis was performed to assess how warming might alter total beta diversity and its components. This experiment was conducted across a gradient of habitat size (bromeliad water volume) and availability of detrital basal resources. A combination of the highest detritus biomass and higher experimental temperatures resulted in the greatest density of flagellates. However, the density of flagellates declined in bromeliads with higher water volume and lower detritus biomass. Moreover, the combination of the highest water volume and high temperature reduced density of copepods. Finally, warming changed microfauna species composition, mostly through species substitution (βrepl component of total beta‐diversity). These findings indicate that warming strongly structures freshwater communities by reducing or increasing densities of different aquatic communities groups. It also enhances beta‐diversity, and many of these effects are modulated by habitat size or detrital resources

Awareness, attitudes and perceptions on epilepsy in Southern Brazil Conhecimento, atitudes e percepções sobre epilepsia no Sul do Brasil

OBJECTIVE: To verify awareness and attitudes toward epilepsy in Southern Brazil. METHOD: A questionnaire about familiarity with the disease, awareness and attitudes toward epileptics was applied to 832 inhabitants of Caxias do Sul. The answers were analyzed in three different groups: G1, non-university students; G2, university students up to the second year; and G3, university students with more than two years education and university graduates. RESULTS: University students and graduates are better informed regarding causes and treatment of epilepsy. Moreover, those interviewees present less negative attitudes toward epileptics. However, a large part of that group lacks some basic information on the disease. CONCLUSION: There is lack of information on epilepsy among Brazilians. Education campaigns should be carried out in order to clarify some aspects concerning epilepsy.<br>OBJETIVO: Verificar o conhecimento e as atitudes sobre epilepsia na população de Caxias do Sul. MÉTODO: Foi aplicado um questionário sobre familiaridade com a doença, conhecimentos e atitudes diante de um portador de epilepsia a 832 moradores da cidade. As respostas foram analisadas em três grupos distintos: G1, não-universitários; G2, universitários até o segundo ano; e G3, universitários com mais de dois anos e graduados. RESULTADOS: Os universitários e graduados possuem melhor conhecimento sobre causas e tratamento da epilepsia. Além disso, esses entrevistados apresentam menos atitudes negativas para com o portador de epilepsia. Entretanto, uma boa parte desse grupo apresenta falta de alguns conhecimentos básicos sobre a doença. CONCLUSÃO: Há falta de informação à população brasileira sobre epilepsia. Campanhas educacionais devem ser realizadas no intuito de desmistificar alguns aspectos concernentes à epilepsia