Navegando por Autor "JUEN, Leandro"

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Acesso aberto (Open Access)
An estimate of the potential number of mayfly species (Ephemeroptera, Insecta) still to be described in Brazil
(Universidade Federal do Pará, 2015-07) MATOS, Mylena Neves Cardoso; FEITOZA, Yulie Shimano; NABOUT, João Carlos; JUEN, Leandro
This study reviewed the data on the Brazilian Ephemeroptera, based on the studies published before July, 2013, estimated the number of species still to be described, and identified which regions of the country have been the subject of least research. More than half the species are known from the description of only one developmental stage, with imagoes being described more frequently than nymphs. The Brazilian Northeast is the region with the weakest database. Body size affected description rates, with a strong tendency for the larger species to be described first. The estimated number of unknown Brazilian species was accentuated by the fact that so few species have been described so far. The steep slope of the asymptote and the considerable confidence interval of the estimate reinforce the conclusion that a large number of species are still to be described. This emphasizes the need for investments in the training of specialists in systematics and ecology for all regions of Brazil to correct these deficiencies, given the role of published papers as a primary source of information, and the fundamental importance of taxonomic knowledge for the development of effective measures for the conservation of ephemeropteran and the aquatic ecosystems they depend on.
Acesso aberto (Open Access)
Baetidae (Insecta, Ephemeroptera) em córregos do cerrado matogrossense sob diferentes níveis de preservação ambiental
(2011-09) SOUZA, Hilton Marcelo de Lima; CABETTE, Helena Soares Ramos; JUEN, Leandro
The effect of different stream environmental preservation levels, in 1st to 4th orders, over the richness, abundance, similarity in the composition and the potential of Baetidae (Ephemeroptera) species as bioindicators were investigated in a Cerrado region located in the state of Mato Grosso, Brazil. A total of twenty species/morphospecies were catalogued from the 1752 samples of nymphs, resulting in a new record for two species in Brazil. Values of Habitat Integrity Index (HII) were categorized among damaged, modified, and preserved environments. Species richness was different between sites, being greater in disturbed habitats. Total abundance was higher among preserved and altered environments, and differed significantly from the degraded areas. The NMDS analysis indicates that, in preserved and modified sites, the similarity in the composition of species differs from degraded areas. Four species showed a positive relationship with increasing values of HII. Baetidae showed environmental indicator species with different levels of preservation, with Zelusia principalis Lugo-Ortiz & McCafferty, 1998 and Baetodes sp. being indicators of preserved environments and Aturbina nigra Salles, Boldrini & Shimano, 2011, Callibaetis sp. 2, Camelobaetidius aff. janae, Paracloeodes binodulus Lugo-Ortiz & McCafferty, 1996 and Waltzoyphius roberti Thomas & Peru, 2002 as indicators of modified environments. The knowledge on the ecology of species advances in terms of providing subsidies for the biomonitoring of basins and the use of indicator species.
Acesso aberto (Open Access)
Composição e riqueza de espécies de anfíbios anuros em três diferentes habitat em um agrossistema no Cerrado do Brasil central
(2013-03) CAMPOS, Vitor Azarias; ODA, Fabrício Hiroiuki; JUEN, Leandro; BARTH, Adriane; DARTORA, Aline
Adaptive plasticity has been postulated as one of the integrating factors that explain the distribution and abundance of species on different habitat with different environmental variations. The environmental heterogeneity is the most important factor for the maintenance, increment or decrement of biodiversity. On this study we determined the effect of periodicity and habitat structure on the richness and composition of species of three different habitat: stream (P1), temporary ponds (P2) and permanent dam (P3) in an agrosystem in the Central Brazilian Cerrado. We performed nine excursions to the field during November 2005 to April 2007. We found and registered the species by direct search and vocalization orientation. We identified 19 anuran species belonging to four families: Bufonidae (one species), Hylidae (nine species), Leptodactylidae (five species), and Leiuperidae (four species). The greatest richness and abundance were recorded in temporary ponds (P2), which differed significantly from the stream (P1) and from the permanent dam (P3). Dendropsophus nanus, Hypsiboas raniceps and Leptodactylus chaquensis showed strong association with P2. P2 and P3 showed greater differentiation between themselves in species composition than when compared to P1. Despite the fact that the studied areas are surrounded by intense farming and present a high degree of anthropic disturbance, these areas showed a high species richness being an important refugee for the amphibians, although the species found on this work are usually associated to impacted areas or open phytophysiognomies and are favored with the creation of artificial environments such as those in this study.
Acesso aberto (Open Access)
Composição e riqueza de Odonata (Insecta) em riachos com diferentes níveis de conservação em um ecótone Cerrado-Floresta Amazônica
(Instituto Nacional de Pesquisas da Amazônia, 2014-06) JUEN, Leandro; OLIVEIRA JUNIOR, José Max Barbosa de; SHIMANO, Yulie; MENDES, Thiago Pereira; CABETTE, Helena Soares Ramos
The removal or substitution of riparian vegetation causes disturbance in physical environment, seasonal water flow and water chemical quality. These modifications can cause decrease in species richness by local extinctions. The aim of this study was to examine the effect of disturbance in the physical environmental on the richness and species composition of Odonata adults in streams with different levels of conservation in the river Suiá-Missu basin, Mato Grosso, Brazil. Modifications in the aquatic systems affected the Odonata community, probably because their ecophysiological and behavioral requirements of adults and larvae. Anisoptera species, which require sunny environments because of their body size, had higher species richness in environments with low plant cover. On the other hand, Zygoptera species, which generally inhabit streams with dense vegetation, presented a decrease in richness in disturbed environments, as a result high sunlight radiation and/or variations in temperature. Hence, in both suborders, environmental perturbations do not need to be severe to change species composition, indicating that ecosystem services could be lost, even with only partial alterations in physical environment.
Acesso aberto (Open Access)
Ecological studies of mayflies (Insecta, Ephemeroptera): can sampling effort be reduced without losing essential taxonomic and ecological information?
(Instituto Nacional de Pesquisas da Amazônia, 2018-06) SHIMANO, Yulie; MATOS, Mylena Neves Cardoso; JUEN, Leandro
The present study evaluated the potential for the reduction of sampling effort in studies of ephemeropteran nymphs in Brazilian Amazon streams, Pará State, Brazil, without the loss of ecological information (species composition, abundance, and richness), and the congruence of different levels of taxonomic resolution (morphospecies, genus, family and functional group). Test groups of 15, 10 and five subsamples were selected from the 20 subsamples collected per stream (40 streams sampled), and were compared in terms of their species richness and abundance (ANOVA), and composition (Procrustes). Taxonomic resolution was also analyzed in Procrustes. Species abundance (F(3, 156) = 25.426; p < 0.001) and richness (F(3, 156) = 13.866, p < 0.001) varied significantly among sample groups, while the results of the 15-S group were statistically similar, in both cases, to those of the 20-S group. A similar pattern was found for species composition. The genus-level taxonomic resolution produced results 99% similar to those found for the species-level data. The results indicate that the reduction in sampling effort from 20 to 15 subsamples per site and a genus-level taxonomic resolution would not affect the reliability of analyses significantly. A reduction of five samples per site would result in a decrease of effort in the field and the amount of material to be processed, reducing laboratory time. In addition to a reduction in the time and resources needed to identify specimens, the adoption of a genus-level taxonomic resolution could help minimize errors of under- or over-estimation in the processing of the results.
Acesso aberto (Open Access)
Effect of waterfalls and the flood pulse on the structure of fish assemblages of the middle Xingu River in the eastern Amazon basin
(Instituto Internacional de Ecologia, 2015-08) BARBOSA, Thiago Augusto Pedroso; BENONE, Naraiana Loureiro; RUFFEIL, Tiago Octavio Begot; GONÇALVES, Alany Pedrosa; SOUSA, Leandro Melo de; GIARRIZZO, Tommaso; JUEN, Leandro; MONTAG, Luciano Fogaça de Assis
The structure of fish assemblages in Neotropical rivers is influenced by a series of environmental, spatial and/or temporal factors, given that different species will occupy the habitats that present the most favourable conditions to their survival. The present study aims to identify the principal factors responsible for the structuring of the fish assemblages found in the middle Xingu River, examining the influence of environmental, spatial, and temporal factors, in addition to the presence of natural barriers (waterfalls). For this, data were collected every three months between July 2012 and April 2013, using gillnets of different sizes and meshes. In addition to biotic data, 17 environmental variables were measured. A total of 8,485 fish specimens were collected during the study, representing 188 species. Total dissolved solids, conductivity, total suspended matter, and dissolved oxygen concentrations were the variables that had the greatest influence on the characteristics of the fish fauna of the middle Xingu. Only the barriers and hydrological periods played a significant deterministic role, resulting in both longitudinal and lateral gradients. This emphasizes the role of the connectivity of the different habitats found within the study area in the structuring of its fish assemblages.
Acesso aberto (Open Access)
Effects of changes in the riparian forest on the butterfly community (Insecta: Lepidoptera) in Cerrado areas
(Universidade Federal do Pará, 2017-03) CABETTE, Helena Soares Ramos; SOUZA, Jaqueline Rodrigues; FEITOZA, Yulie Shimano; JUEN, Leandro
Preserved riparian vegetation usually has greater environmental complexity than the riparian vegetation modified by human actions. These systems may have a greater availability and diversity of food resources for the species. Our objective was to evaluate the effect of changes on the structure of the riparian forest on species richness, beta diversity and composition of butterfly species in the Cerrado of Mato Grosso. We tested the hypotheses that: (i) higher species richness and (ii) beta diversity would be recorded in more preserved environments; and (iii) species composition would be more homogeneous in disturbed habitats. For hypothesis testing, the riparian vegetation of eight streams were sampled in four periods of the year in a fixed transect of 100 m along the shores. The richness of butterfly species is lower in disturbed than in preserved areas. However, species richness is not affected by habitat integrity. Beta diversity differed among sites, such that preserved sites have greater beta diversity, showing greater variation in species composition. In addition, beta diversity was positively affected by environmental heterogeneity. A total of 23 of the 84 species sampled occurred only in the changed environment, 42 were exclusive to preserved sites and 19 occurred in both environments. The environmental change caused by riparian forest removal drastically affects the butterfly community. Therefore, riparian vegetation is extremely important for butterfly preservation in the Cerrado and may be a true biodiversity oasis, especially during the dry periods, when the biome undergoes water stress and resource supply is more limited.
Acesso aberto (Open Access)
Effects of marginal vegetation removal on Odonata communities
(Associação Brasileira de Limnologia, 2013-03) CARVALHO, Fernando Geraldo de; PINTO, Nelson Silva; OLIVEIRA JUNIOR, José Max Barbosa de; JUEN, Leandro
AIM: Here we assess the effects of habitat degradation on individuals of the two suborders of Odonata community of Borecaia river sub-basin. More specifically, we tested the hypothesis that Anisoptera richness would be positively affected by removal of vegetation; on the other hand, Zygoptera richness would be adversely affected by virtue of their ecophysiological requirements; METHODS: We selected 10 streams of similar orders, six preserved and four degraded. Streams characterized as preserved had values of Index of Habitat Integrity (HII) above 0.70 (0.77 ± 0.07, mean ± SD) and continuous forest on both sides with a minimum width of 70 meters. Each site was sampled three times on different days. The effect of vegetation removal on richness was assessed using richness estimated by first order Jackknife; RESULTS: Decreased physical integrity (measured with IIH) of streams had no significant effect on the estimated richness to Odonata in general. However, the estimated richness of Anisoptera showed an inverse relationship with the integrity (r2 = 0.485, P = 0.025), i.e., there was a reduction in their species richness with increasing integrity; DISCUSSION: As a general pattern, Anisoptera presents higher richness in an altered site; on the other hand, Zygoptera presents higher richness in a preserved one. This pattern suggests that Odonata needs to be considered at the sub-order level to access the effects of habitat degradation on these insects. Because of its restrictions ecophysiological Odonata varied widely in their composition and species richness between the two types of environments, it reinforces the potential of the order of studies and environmental monitoring also shows that Zygoptera be more affected by changes in habitat. However, further studies including more samples and different streams are need to confirm this pattern, being an interesting line of research for future works.
Acesso aberto (Open Access)
Emergence trap for the collection of exuviae and adult of Odonata
(Universidade Federal do Rio de Janeiro, 2020) RESENDE, Bethânia Oliveira de; FERREIRA, Victor Rennan Santos; JUEN, Leandro; CABETTE, Helena Soares Ramos
Odonates have aquatic larval stages and terrestrial adults. The extreme change in habitat occupation during their life cycle means that combined collection methods, capable of providing data for both larvae and adults, are scarce and are often inefficient. Given this, we applied a method for the collection of specimens of both life phases using emergence traps. During fieldwork, 78 emergence events were recorded for 15 species. We also briefly discuss the emergence pattern of the recorded species. We believe the information obtained here provide an important contribution to the understanding of the ecology and basic biology of Neotropical odonate species, as well as helping to solve the taxonomic problems associated with the identification of larvae.
Acesso aberto (Open Access)
Estrutura e composição da comunidade de Trichoptera (Insecta) de rios e áreas alagadas da bacia do rio Suiá-Miçú, Mato Grosso, Brasil
(2011-09) NOGUEIRA, Denis Silva; CABETTE, Helena Soares Ramos; JUEN, Leandro
The composition, abundance and species diversity of Trichoptera immatures was studied in 12 tributaries of Suiá-Miçú River Basin, a mosaic of wetlands, streams and rivers tributary of the Xingu River in the Cerrado-Amazonian Forest transition zone in Mato Grosso, Brazil. The varying sizes, flow types and conservation levels of the tributaries were sampled through three periods between 2007 and 2008 by the use of fixed transects along the environments margins. A total of 867 larvae was collected (divided in seven families, 17 genera, 49 species/morphospecies) with the most abundant and rich families being Hydropsychidae and Leptoceridae and the most abundant species Leptonema sparsum (n = 370). There has been loss of species richness in impacted, large and lentic environments. Composition variations related to the flow, the vegetation type and the interaction between conservation levels and flow was detected. Conservation levels, width and the quantitative habitat integrity index (HII) did not influence the Trichoptera composition. These results may encourage further investigation of impact effects on aquatic insect compositions and pattern of distribution in the transition area between the Cerrado and the Amazonian Forest.
Acesso aberto (Open Access)
Setting boundaries: Environmental and spatial effects on Odonata larvae distribution (Insecta)
(2015-03) MENDES, Thiago Pereira; CABETTE, Helena Soares Ramos; JUEN, Leandro
Environmental characteristics and spatial distances between sites have been used to explain species distribution in the environment, through Neutral (space) and Niche theory (environment) predictions. We evaluated the effects of spatial and environmental factors on Odonata larvae distribution along the Suiá-Missú River Basin, state of Mato Grosso. We tested the hypotheses that (1) the environment is the main factor structuring the community due to its ecophysiological requirements; and (2) the pattern, if present, is clearer for Zygoptera. Samples were made in 12 sites on the Suiá-Missú River Basin in three seasons (2007/2008), with a total of 1.382 Odonata larvae, comprising 10 families, 51 genera and 100 morphospecies. The Anisoptera were more abundant than Zygoptera, comprising 81% of all specimens. The environment affected Zygoptera (R=0.291; p=0.007) and was the main factor structuring the assembly. Thus, Niche theory was confirmed. The absence of this effect on Anisoptera may be due to the ecophysiological adaptations that enable it to occupy different habitats. Zygoptera larvae are indicators of changes in habitat structure. The effects of environmental variables on larvae ecology emphasize the strong relationship between these organisms and environmental integrity.
Acesso aberto (Open Access)
Study of the mayfly order Ephemeroptera (Insecta) in Brazil: a scienciometric review
(Universidade Federal do Pará, 2013-12) SHIMANO, Yulie; SALLES, Frederico Falcão; JUEN, Leandro
Study of the mayfly order Ephemeroptera (Insecta) in Brazil: a scienciometric review. Despite an increase in the number of studies in recent years of the aquatic insect order Ephemeroptera (the mayflies) much still remains to be learnt. In order to identify the current state of knowledge of this group in Brazil, we performed a scienciometric analysis with the purpose of identifying the strong and weak points of Brazilian research into the group. Our research used the "Institute for Scientific Information - ISI" database and was based on the abstracts, titles and keywords of manuscripts published between 1992 and 2011. We selected the papers with the combination of the words "Ephemeroptera" and "Brazil*" based on a search in February 2012. We analyzed 92 articles, and noted a lack of studies in some Brazilian states, no specific studies about some families, and an absence of phylogenetic studies. To improve ecological studies, it is necessary to fine-tune taxonomic resolution. Moreover, there is a lack of studies investigating the environmental variables which influence the distribution of mayflies. Despite these gaps, if the rate of publication with mayflies proceeds at the same pace, we anticipate that many of these knowledge gaps will be closed.