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Food habits of Rhinella proboscidea (Anura: Bufonidae) in terra firme forests of central Amazonia
Get PDFAnuran species are considered generalist and opportunist feeders. However, some species have dietary specializations. Here we describe the diet composition of Rhinella proboscidea based on the stomach content of 29 individuals captured in terra firme forests in Manaus and São Sebastião do Uatumã, state of Amazonas, Brazil. Each prey item was measured and identified to Order, Suborder or Family; ants were identified to Genus. We determined and tested for differences in the trophic niche breadth and the relationships between the frog size and the volume of the largest prey item. We recorded 1614 prey items of 44 taxa. Hymenoptera was the most abundant Order followed by Isoptera, Acari, Coleoptera, Orthoptera, Araneae, Hemiptera, Dermaptera, Diptera, and Collembola. Formicidae comprised 46.56% of the all stomach items and was represented by six subfamilies and 22 genera. Additionally, we found 80 nematodes in a total of 18 frogs. There was a significant difference in the trophic niche breadths of the study areas, and a positive relationship between the toad size and volume of the largest prey item consumed. Rhinella proboscidea feeds on a variety of invertebrates, with ants, termites, and mites being the most abundant; this suggests that the toad is an active forager. The most common subfamily was Myrmicinae primarily represented by Crematogaster and Atta. Differences in trophic niche breadths of the study areas may be related to seasonal differences in the diet composition or local factors. © 2019 ESALQ Universidade de Sao Paolo. All rights reserved
Aspectos da relação pessoa-animal na conservação da fauna silvestre amazônica em risco de extinção
No full textMonitoramento da Resistência e dos Efeitos em Parâmetros Biológicos de Aedes aegypti Linnaeus, 1762 (Diptera: Culicidae) de Manaus, Amazonas, Exposto ao Biolarvicida Espinosade, em Condições de Laboratório
Get PDFThe control of mosquito vectors with insecticides is the most efficient tool to contain the transmission of pathogens, with spinosad biolarvicida being one of the most used control agents in the world due to its high toxicity to insects of different orders. In this regard, it is important to monitor the effectiveness of the product over generations to be able to target better control strategies. This study aimed to verify the resistance rate of Aedes aegypti submitted to selection pressure with larvicide spinosad under laboratory conditions, and to analyze the effects of this exposure on developmental and reproductive aspects. The selection was performed for six generations, with analyzes on the biological parameters of generations F2 and F6. The LC50 (0.036 mg/L) used in the tests increased in the F3 (0.114 mg/L) and F6 (0.101 mg/L) generations of the biolarvicide pressured population, with significant differences between F1 and F3 (p= 0.0019), and between F1 and F6 (p= 0.0187). However, there was no significant difference between F3 and F6 values (p> 0.05). The Resistance Ratio (RR) values obtained in this study (1.1; 1.3; 2.8; 3.2) were considered low. The mean time of the larval stage and the biological cycle of the population exposed to the biolarvicida were higher in F6 compared to the control population (p= 0.0001). The body weight of the females of the population exposed to the biolarvicida in the two conditions evaluated (before and after the repast) was lower than the control females (p= 0.0001). The oviposition rate of the females of the population exposed to the biolarvicida from F2 was low in comparison to the control population (p= 0.0001). However, even if the LC50 changes over the generations, the population is still considered to have a low level of resistance to the biolarvicide, according to the RR values and WHO parameters. Therefore, new experiments are needed to analyze the evolution of resistance in the laboratory. In addition, after six generations, spinosad negatively affected the mean larval stage and life cycle time A. aegypti, demonstrating that the insects of the pressured population took longer to develop. In addition, females body weight before and after the meal, as well as fecundity, were promptly reduced. Evidencing that larvicide affected reproductive aspects, which are related to the vector capacity of the species.O controle de mosquitos vetores com inseticidas é a ferramenta mais eficiente para conter a transmissão de patógenos, sendo o biolarvicida espinosade um dos agentes de controle mais utilizados no mundo, devido à sua alta toxicidade para insetos de diferentes ordens. Neste aspecto, é importante monitorar a eficácia do produto ao longo de gerações, para poder direcionar melhores estratégias de controle. O presente estudo objetivou verificar a taxa de resistência de Aedes aegypti submetido à pressão de seleção com o larvicida espinosade, em condições de laboratório, além de analisar os efeitos desta exposição em aspectos do desenvolvimento e da reprodução. A seleção foi realizada por seis gerações, com análises nos parâmetros biológicos das gerações F2 e F6. A CL50 (0,036 mg/L) utilizada nos testes, aumentou nas gerações F3 (0,114 mg/L) e F6 (0,101 mg/L) da população pressionada com o biolarvicida, com diferenças significativas entre F1 e F3 (p= 0,0019), e entre F1 e F6 (p= 0,0187). No entanto, não houve diferença significativa entre os valores da F3 e F6 (p>0,05). Os valores de Razão de Resistência (RR) obtidos neste estudo (1,1; 1,3; 2,8; 3,2) foram considerados baixos. O tempo médio do estágio larval e do ciclo biológico da população pressionada foram maiores na F6 em comparação a população controle (p= 0,0001). O peso corporal das fêmeas da população pressionada nas duas condições avaliadas (antes e após o repasto) foi inferior ao das fêmeas da população controle (p= 0,0001). A taxa de oviposição das fêmeas da população pressionada oriundas da F2 foi baixa em comparação à da população controle (p= 0,0001). Contudo, mesmo ocorrendo alteração da CL50 ao longo das gerações, a população ainda é considerada com baixo nível de resistência ao biolarvicida, de acordo com os valores de RR e os parâmetros da OMS. Portanto, novos experimentos são necessários para analisar a evolução da resistência, em laboratório. Além disso, após seis gerações, o espinosade afetou negativamente o tempo médio do estágio larval e do ciclo de vida de A. aegypti, demonstrando que os insetos da população pressionada demoraram mais tempo para se desenvolver. Além do mais, o peso corporal das fêmeas antes e após o repasto, bem como a fecundidade, foram prontamente reduzidos. Evidenciando que o larvicida afetou aspectos reprodutivos, os quais são relacionados a capacidade vetorial da espécie
Avaliação da qualidade ambiental em um sistema de lagos manejados na região do baixo Rio Solimões, Amazônia, Brasil
Get PDFThe management of lakes has been efficient in the recovery of fish stocks in the Amazon. However, little is known about the effects of the management system on lakes for the quality of these environments. Evaluating the implications of this system for environmental quality can be a difficult process due to the limited tools available for floodplain environments in the Amazon. The Biotic Integrity Index (BII) is a tool that has been shown to be promising, accessible, easy to understand, and inexpensive to monitor biological resources. The aim of this study was to evaluate the impact of the management system on the environmental quality of lakes through the use of the BII in the region of the lower Solimões River, in the Amazon region of Brazil. For the capture of fish, gill nets were arranged in six lakes, which belong to three management categories: preservation, management and commercial use. A total of five samples were sampled in 2017 and early 2018. The number of fish sampled was 4565, distributed six orders, 25 families and 113 species. The final index was composed of seven metrics related to species richness and composition, trophic structure and abundance of fish. By means of BII, we evaluated that the environmental quality in the preservation lakes is good, in the management lakes the quality is regular and in the lakes of commercial use the quality is poor. We confirmed the results of the BII through multivariate statistics that allowed us to reject the hypothesis that the environmental quality in lakes is not influenced by the management system in lakes, in such a way that we verify that preservation lakes have better quality than management lakes and commercial use. The classification determined by the IIB shows that the management system is a satisfactory model to assure the environmental quality in the lakes, indicating through the response of the ichthyofauna, that this system present in the island of Paciência - implemented through the fishing agreement - fulfills its role of preserving the fishing stock and alternatively contributes to the quality of the environment as a whole.O manejo de lagos tem se mostrado eficiente na recuperação do estoque pesqueiro na Amazônia. No entanto, pouco se sabe sobre os efeitos do sistema de manejo em lagos para a qualidade do ambiente. Avaliar as implicações deste sistema de gestão para a qualidade ambiental pode ser um processo dificultoso diante da limitação de ferramentas disponíveis para ambientes de várzea na Amazônia. O Índice de Integridade Biótica (IIB) é uma ferramenta que tem se mostrado promissora, acessível, de fácil entendimento e de baixo custo para o monitoramento dos recursos biológicos. Diante disso, este trabalho objetivou avaliar o reflexo do sistema de manejo na qualidade ambiental de lagos por meio da utilização do IIB, na região do baixo rio Solimões, Amazônia, Brasil. Para a captura de peixes, foram utilizadas redes de emalhar dispostas em seis lagos pertencentes a três categorias de manejo: preservação, manejo e uso comercial. As coletas, um total de cinco, ocorreram no ano de 2017 e início do ano de 2018. O número de peixes amostrados foi de 4565, distribuídos seis ordens, 25 famílias e 113 espécies. O índice final foi composto por sete métricas referente à riqueza e composição de espécies, estrutura trófica e abundância de peixes. Por meio do IIB, avaliamos que a qualidade ambiental nos lagos de preservação é boa, nos lagos de manejo a qualidade é regular e nos lagos de uso comercial a qualidade é pobre. Confirmamos o resultado obtido pelo índice por meio de estatística multivariada que permitiu rejeitar a hipótese de que a qualidade ambiental dos lagos não é influenciada pelo sistema de manejo em lagos, de tal forma que verificamos que lagos de preservação possui melhor qualidade do que lagos de manejo e de uso comercial. A classificação determinada pelo IIB evidencia que o sistema de manejo é um modelo satisfatório para assegurar a qualidade ambiental nos lagos de várzea, indicando por meio da resposta da ictiofauna que este sistema vigente na ilha da Paciência - implantado por meio do acordo de pesca - cumpre seu papel de preservação do estoque pesqueiro e alternativamente contribui para a boa qualidade do ambiente como um todo
Heart structure in the Amazonian teleost Arapaima gigas (Osteoglossiformes, Arapaimidae)
No full textThe fish heart ventricle has varied morphology and may have a specific morpho-functional design in species adapted to extreme environmental conditions. In general, the Amazonian ichthyofauna undergoes constant variations in water temperature, pH and oxygen saturation, which makes these species useful for investigations of cardiac morphology. Arapaima gigas, a member of the ancient teleost group Osteoglossomorpha, is one of the largest freshwater fish in the world. This species has a specific heart metabolism that uses fat as the main fuel when O 2 supplies are abundant but also can change to glycogen fermentation when O 2 content is limiting. However, no information is available regarding its heart morphology. Here, we describe the heart of A. gigas, with emphasis on the ventricular anatomy and myoarchitecture. Specimens of A. gigas weighing between 0.3 and 4040 g were grouped into three developmental stages. The hearts were collected and the anatomy analyzed with a stereomicroscope, ultrastructure with a scanning electron microscope, and histology using toluidine blue, Masson's trichrome and Sirius red stains. The ventricle undergoes morphological changes throughout its development, from the initial saccular shape with a fully trabeculated myocardium and coronary vessel restricted to the subepicardium (Type I) (group 1) to a pyramidal shape with mixed myocardium and coronary vessels that penetrate only to the level of the compact layer (Type II) (groups 2 and 3). The trabeculated myocardium has a distinct net-like organization in all the specimens, differing from that described for other teleosts. This arrangement delimits lacunae with a similar shape and distribution, which seems to allow a more uniform blood distribution through this myocardial layer. © 2018 Anatomical Societ
Ostracoda impairs growth and survival of Arapaima gigas larvae
No full textThe practice of indoor larviculture can be an alternative to enhance the rearing of arapaima larvae, improving their survival and the supply of arapaima juveniles for the grow-out stage. We aimed to evaluate different live microcrustaceans as feed for arapaima larvae to verify groups that can be safely used in laboratory trials, as well as in commercial larviculture. Arapaima larvae (39.45 ± 7.04 mg and 2.09 ± 0.13 cm) were housed in 12-L circular tanks (n = 4 tanks; 30 larvae per tank) in a static water system. The tanks were cleaned twice a day, when 50% of the water was changed. Fish were fed three types of live feed 9 times/day: brine shrimp Artemia sp. nauplii (AR), Cladocera-rich zooplankton (CZ), and Ostracoda-rich zooplankton (OZ) for 15 days. Fish fed CZ and AR showed a similar fast growth rate with low mortality rates. The OZ fed Arapaima larvae presented intact Ostracoda in their rectums. This findins, demonstrates their poor digestibility, which resulted in poor growth and low survival. Ostracoda-rich zooplankton must be avoided in arapaima larviculture until 8 days after they begin swimming to the water surface or 17 days after hatching. © 201
Combining LiDAR and hyperspectral data for aboveground biomass modeling in the Brazilian Amazon using different regression algorithms
No full textAccurate estimates of aboveground biomass (AGB) in tropical forests are critical for supporting strategies of ecosystem functioning conservation and climate change mitigation. However, such estimates at regional and local scales are still highly uncertain. Airborne Light Detection And Ranging (LiDAR) and Hyperspectral Imaging (HSI) can characterize the structural and functional diversity of forests with high accuracy at a sub-meter resolution, and potentially improve the AGB estimations. In this study, we compared the ability of different data sources (airborne LiDAR and HSI, and their combination) and regression methods (linear model - LM, linear model with ridge regularization - LMR, Support Vector Regression - SVR, Random Forest - RF, Stochastic Gradient Boosting - SGB, and Cubist - CB) to improve AGB predictions in the Brazilian Amazon. We used georeferenced inventory data from 132 sample plots to obtain a reference field AGB and calculated 333 metrics (45 from LiDAR and 288 from HSI) that could be used as predictors for statistical AGB models. We submitted the metrics to a correlation filtering followed by a feature selection procedure (recursive feature elimination) to optimize the performance of the models and to reduce their complexity. Results showed that both LiDAR and HSI data used alone provided relatively high accurate models if adequate metrics and algorithms are chosen (RMSE = 67.6 Mg.ha−1, RMSE% = 36%, R2 = 0.58, for the best LiDAR model; RMSE = 68.1 Mg.ha−1, RMSE% = 36%, R2 = 0.58, for the best HSI model). However, HSI-only models required more metrics (5–12) than LiDAR-only models (2–5). Models combining metrics from both datasets resulted in more accurate AGB estimates, regardless of the regression method (RMSE = 57.7 Mg.ha−1, RMSE% = 31%, R2 = 0.70, for the best model). The most important LiDAR metrics for estimating AGB were related to the upper canopy cover and tree height percentiles, while the most important HSI metrics were associated with the near infrared and shortwave infrared spectral regions, particularly the leaf/canopy water and lignin-cellulose absorption bands. Finally, an analysis of variance (ANOVA) showed that the remote sensing data source (LiDAR, HSI, or their combination) had a greater effect size than the regression algorithms. Thus, no single algorithm outperformed the others, although the LM method was less suitable when applied to the HSI and hybrid datasets. Results show that the synergistic use of LiDAR and hyperspectral data has great potential for improving the accuracy of the biomass estimates in the Brazilian Amazon. © 2019 Elsevier Inc
Hydraulic traits explain differential responses of Amazonian forests to the 2015 El Niño-induced drought
No full textReducing uncertainties in the response of tropical forests to global change requires understanding how intra- and interannual climatic variability selects for different species, community functional composition and ecosystem functioning, so that the response to climatic events of differing frequency and severity can be predicted. Here we present an extensive dataset of hydraulic traits of dominant species in two tropical Amazon forests with contrasting precipitation regimes – low seasonality forest (LSF) and high seasonality forest (HSF) – and relate them to community and ecosystem response to the El Niño–Southern Oscillation (ENSO) of 2015. Hydraulic traits indicated higher drought tolerance in the HSF than in the LSF. Despite more intense drought and lower plant water potentials in HSF during the 2015-ENSO, greater xylem embolism resistance maintained similar hydraulic safety margin as in LSF. This likely explains how ecosystem-scale whole-forest canopy conductance at HSF maintained a similar response to atmospheric drought as at LSF, despite their water transport systems operating at different water potentials. Our results indicate that contrasting precipitation regimes (at seasonal and interannual time scales) select for assemblies of hydraulic traits and taxa at the community level, which may have a significant role in modulating forest drought response at ecosystem scales. © 2019 The Authors. New Phytologist © 2019 New Phytologist Trus
Structure and regional representativeness of the herpetofauna from Parque Estadual da Serra de Caldas Novas, Cerrado, Central Brazil
Get PDFAmphibians and reptiles are diversified in the Cerrado biome but have been threatened by habitat loss and fragmentation, as well as lack of understanding of their distribution. Therefore, collection and organization of information about species in natural environments are essential for conservation, especially in Protected areas (PAs) and their adjacent zones. We present information about the composition and structure of the herpetofauna from Parque Estadual da Serra de Caldas Novas (PESCAN) and its representativeness in comparison to other PAs in the Cerrado. Fieldwork was conducted in 12 sampling sites from February 2009 to February 2010, using active search and pitfall traps. We recorded 41 species of amphibians, with greatest richness in sites with open vegetation and water bodies. Reptiles were represented by 32 species, with the greatest species richness in cerrado open environments. Both amphibian and reptile communities were more similar to those from geographically closer PAs and located in the central region of the Cerrado (State of Goiás and Distrito Federal). The PESCAN holds 24.85% and 17.98% of amphibians and reptiles species occurring in Cerrado PAs, respectivelly. This large representativeness and the high number of endemisms (18 amphibians and 7 reptiles) emphasize the importance of the PESCAN, together with other PAs, for the maintenance of regional biodiversity. In addition, we also encourage researches evaluating amphibian and reptile communities outside PAs, such as legal reserves, and we suggest new approaches to study the biodiversity of protected areas. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group