Discursos de Educação Ambiental produzidos por professores em formação continuada

O presente trabalho se localiza nos estudos da educação ambiental (EA) e do discurso. Teve como objetivo caracterizar a intertextualidade presente nos discursos de EA produzidos por professores em formação continuada durante um Curso de Formação de Educadores Ambientais (CFEA). O referencial teórico e metodológico utilizado foi a análise crítica do discurso. O corpus consistiu de textos transcritos de uma atividade em grupo durante o curso e entrevistas com três participantes após o curso. Os textos foram analisados qualitativamente por meio da análise da intertextualidade. Os resultados permitiram entender que os discursos de EA das participantes são construídos a partir de diferentes abordagens de EA. Tais abordagens se interpelam e constituem um discurso plural. Assim, os discursos mostraram a uma articulação complexa entre os diferentes discursos que circularam no CFEA e ainda com outros textos de EA com os quais as participantes provavelmente tiveram contato ao longo de sua trajetória

PHYTOPLANKTON BIOMASS INCREASES IN A SILT-IMPACTED AREA IN AN AMAZONIAN FLOOD-PLAIN LAKE OVER 15 YEARS

Funding Information: We thank Mineração Rio do Norte S.A. and Limnologia/UFRJ for fieldwork support, Dr. Janet W. Reid (JWR Associates) for language revision, and Leonardo Preza Rodrigues for map charting. VLMH, JCN, FAE, RLB, and FR are partially supported by the National Council for Scientific and Technological Development (CNPq), Brazil, RLB, and FAE by FAPERJ, Brazil, and CGR financially supported by Sakari Alhopuro Foundation, Finland. Publisher Copyright: © 2022, Universidade Federal do Rio de Janeiro. All rights reserved.Tailings from bauxite mining in Porto Trombetas (Pará state, Central Amazonia, Brazil) was discharged (1979–1989) into Batata Lake affecting about 30% of its area. The lake belongs to a clear-water flood-plain system along the Trombetas River, a tributary of the Amazon River. Siltation is the main perceived factor impacting aquatic and flooded communities. Besides natural regeneration, a program to restore a section of igapó forest in the impacted area (IA) has been conducted since 1991. Decreased light is the main factor reducing total phytoplankton biomass (PhyBM) in IA. We hypothesized that PhyBM in IA increases over time because of the improvement of the underwater light conditions due to the natural regeneration and restoration. We sampled quarterly PhyBM and limnological variables (depth, transparency, temperature, pH, conductivity, dissolved oxygen, turbidity, suspended solids, total Kjeldahl nitrogen, and total phosphorus), over 15 years (2005–2019) at eight sampling sites in the two areas (N = 349). We also obtained daily climatic and hydrologic data. PhyBM was higher in NIA than in IA. The temporal trend in the annual mean of PhyBM increased significantly over time only in the IA, approximating the NIA values, confirming our general hypothesis. The increase of PhyBM in the IA was negatively related to the residual light attenuation caused by non-phytoplankton turbidity and to total phosphorus, and positively to air temperature and site depth (p < 0.05; Marginal r2 = 0.18; Conditional r2 = 0.29). Instead, in NIA, PhyBM was explained only by the increase in air temperature (p < 0.05; Marginal r2 = 0.15; Conditional r2 = 0.34). We concluded that the PhyBM in the IA positively responds to the synergy between increasing light availability, air temperature, and site depth, and decreasing total phosphorus concentrations, regardless of hydrologic phase.Peer reviewe

Richness of Dendrocephalus (Branchiopoda, Anostraca) in Brazil with the description of two new species

International audienceWe present an overview of the morphological diversity and geographical distribution of the anostracan genus Dendrocephalus Daday, 1908, and describe two new species: D. aranai sp. nov. from Jequitinhonha in the state of Minas Gerais and D. xikrini sp. nov. from the Carajás Mountains (Serra dos Carajás) in the state of Pará. These species have important similarities to D. goiasensis Rabet & Thiéry, 1996 and D. thieryi Rabet, 2006, respectively, but differ from them and each other through a combination of characters that are essentially unique to the endopods, and frontal appendage branch 2A and branch 2D. We also partly redescribe D. carajaensis Rogers, Gomes & Vieira, 2012, which shows a particular intra-populational variability in branch 2A and 2D III of the frontal appendage, a type of polymorphism that was also recently observed in D. orientalis Rabet & Thiéry, 1996 and which must now be taken into account in taxonomy. In terms of the distribution of species of Dendrocephalus in Brazil, we suggest that several other species are probably present in the Amazonian, Cerrado and Pantanal Biomes, which remain largely unexplored. A new taxonomic key for the identification of males of the Brazilian species is provided

A Big Bang or small bangs? Effects of biotic environment on hatching

The beginning and end of diapause are two important transition points in cladoceran life history. The influence of environmental variables on the dynamics of these processes still deserves attention, especially as concerns the role of biotic factors. In this paper we focus on emergence from diapause, testing (1) whether ephippia of Daphnia obtusa Kurz can assess the presence in the water of typical planktivorous fish or ostracods, and (2) whether such an assessment results in changes in hatching strategy. Total number of hatchlings from D. obtusa ephippial eggs did not differ between the control and the treatments in which the presence of fish or ostracods could be detected (ANOVA, P = 0.884). However, hatching dynamics were different: most of the eggs hatched synchronously at day 4 (83.3% of the total hatchlings number) in the control, while only a low proportion of eggs hatched on day 4 in the fish (38.3%), and ostracod treatments (24.0% of the total). Mean hatching time was longer, and variability larger, in the treatments than in the control; differences resulted statistically significant (ANOVA, P = 0.005). With respect to the control, representing a simple microcosm controlled by abiotic variables only, the treatments may be regarded as relatively complex environments, in which Daphnia is also exposed to biotic cues. Under these more complex conditions, the same number of hatchlings is obtained through different hatching dynamics. In the treatments, the first hatchlings appeared later and the hatching rate was more variable than in the control. These observations confirm previously observed patterns from laboratory experiments which tested the effect of competition and fluctuating environmental conditions (light:dark, temperature regimes) on D. obtusa reproductive and demographic parameters. They are also in agreement with recently obtained evidence concerning the importance of biotic cues for hatching of ephippial eggs. Overall, the evidence suggests that Daphnia can detect infochemicals during dormancy. Specifically, we propose that the presence in the water medium of potential predators and competitors results in a short-term hatching asynchrony of ephippial eggs

Viruses and bacteria in floodplain lakes along a major Amazon tributary respond to distance to the Amazon River

Because of the massive water volume of the Amazon River, the Amazon tributaries have their water backed up by hundreds of kilometers upstream their mouth. This backwater effect is part of the complex hydrodynamics of Amazonian surface waters, which in turn drives the variation in concentrations of organic matter and nutrients, and also regulates planktonic communities such as viruses and bacteria. Viruses and bacteria are commonly tightly coupled, and their ecological role in aquatic food webs has been increasingly recognized. Here, we surveyed viral and bacterial abundances in 26 floodplain lakes along the Trombetas River, the largest clear-water tributary of the Amazon River’s north margin. We correlated viral and bacterial abundances with temperature, pH, dissolved inorganic carbon, dissolved organic carbon (DOC), phosphorus, nitrogen, turbidity, water transparency, partial pressure of carbon dioxide (pCO2), phytoplankton abundance and distance from the lake mouth until the confluence of the Trombetas with the Amazon River. We hypothesized that both bacterial and viral abundances would change along a latitudinal gradient, as the backwater effect becomes more intense with increased proximity to the Amazon River; different flood duration and intensity among lakes and waters with contrasting sources would cause spatial variation. Our measurements were performed during the low water period, when floodplain lakes are in their most lake-like conditions. Viral and bacterial abundances, DOC, pCO2 and water transparency increased as distance to the Amazon River increased. Most viruses were bacteriophages, as viruses were strongly linked to bacteria, but not to phytoplankton. We suggest that bacterial abundances increase in response to DOC quantity and possibly quality, consequently leading to increased viral abundances. Our results highlight that hydrodynamics plays a key role in the regulation of planktonic viral and bacterial communities in Amazonian floodplain lakes

Food web architecture and basal resources interact to determine biomass and stoichiometric cascades along a benthic food web.

Understanding the effects of predators and resources on primary producers has been a major focus of interest in ecology. Within this context, the trophic cascade concept especially concerning the pelagic zone of lakes has been the focus of the majority of these studies. However, littoral food webs could be especially interesting because base trophic levels may be strongly regulated by consumers and prone to be light limited. In this study, the availability of nutrients and light and the presence of an omnivorous fish (Hyphessobrycon bifasciatus) were manipulated in enclosures placed in a humic coastal lagoon (Cabiúnas Lagoon, Macaé - RJ) to evaluate the individual and interactive effects of resource availability (nutrients and light) and food web configuration on the biomass and stoichiometry of periphyton and benthic grazers. Our findings suggest that light and nutrients interact to determine periphyton biomass and stoichiometry, which propagates to the consumer level. We observed a positive effect of the availability of nutrients on periphytic biomass and grazers' biomass, as well as a reduction of periphytic C∶N∶P ratios and an increase of grazers' N and P content. Low light availability constrained the propagation of nutrient effects on periphyton biomass and induced higher periphytic C∶N∶P ratios. The effects of fish presence strongly interacted with resource availability. In general, a positive effect of fish presence was observed for the total biomass of periphyton and grazer's biomass, especially with high resource availability, but the opposite was found for periphytic autotrophic biomass. Fish also had a significant effect on periphyton stoichiometry, but no effect was observed on grazers' stoichiometric ratios. In summary, we observed that the indirect effect of fish predation on periphyton biomass might be dependent on multiple resources and periphyton nutrient stoichiometric variation can affect consumers' stoichiometry