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The osmorespiratory compromise: Physiological responses and tolerance to hypoxia are affected by salinity acclimation in the euryhaline Atlantic killifish (Fundulus heteroclitus)
Get PDFThe characteristics of the fish gill that maximize gas exchange are the same that promote diffusion of ions and water to and from the environment; therefore, physiological trade-offs are likely to occur.Here, we investigated how salinity acclimation affects whole-animal respiratory gas exchange during hypoxia using Fundulus heteroclitus, a fish that inhabits salt marshes where salinity and oxygen levels vary greatly. Salinity had marked effects on hypoxia tolerance, with fish acclimated to 11 and 35 ppt showing much longer time to loss of equilibrium(LOE) in hypoxia than 0 ppt-acclimated fish. Fish acclimated to 11 ppt (isosmotic salinity) exhibited the greatest capacity to regulate oxygen consumption rate (MO2) under hypoxia, as measured through the regulation index (RI) and Pcrit. At 35 ppt, fish had a higher routine metabolic rate (RMR) but a lower RI than fish at 11 ppt, but there were no differences in gill morphology, ventilation or blood O2 transport properties between these groups. In contrast, 0 ppt-acclimated fish had the highest ventilation and lowest O2 extraction efficiency in normoxia and hypoxia, indicating a higher ventilatory workload in order to maintain similar levels of MO2. These differences were related to alterations in gill morphology, where 0 ppt-acclimated fish had the smallest lamellar surface area with the greatest epithelial cell coverage (i.e. thicker lamellae, longer diffusion distance) and a larger interlamellar cell mass, contrasting with 11 ppt-acclimated fish, which had overall the highest respiratory surface area. The alteration of an array of physiological parameters provides evidence for a compromise between salinity and hypoxia tolerance in killifish acclimated to freshwater. © 2019. Published by The Company of Biologists Ltd | Journal of Experimental Biology
On the relationship between suspended sediment concentration, rainfall variability and groundwater: An empirical and probabilistic analysis for the Andean Beni River, Bolivia (2003-2016)
Get PDFFluvial sediment dynamics plays a key role in the Amazonian environment, with most of the sediments originating in the Andes. The Madeira River, the second largest tributary of the Amazon River, contributes up to 50% of its sediment discharge to the Atlantic Ocean, most of it provided by the Andean part of the Madeira basin, in particular the Beni River. In this study, we assessed the rainfall (R)-surface suspended sediment concentration (SSSC) and discharge (Q)-SSSC relationship at the Rurrenabaque station (200 m a.s.l.) in the Beni Andean piedmont (Bolivia). We started by showing how the R and Q relationship varies throughout the hydrological year (September to August), describing a counter-clockwise hysteresis, and went on to evaluate the R-SSSC and Q-SSSC relationships. Although no marked hysteresis is observed in the first case, a clockwise hysteresis is described in the second. In spite of this, the rating curve normally used (SSSC = aQb) shows a satisfactory R2 = 0.73 (p < 0.05). With regard to water discharge components, a linear function relates the direct surface flow Qs-SSSC, and a hysteresis is observed in the relationship between the base flow Qb and SSSC. A higher base flow index (Qb/Q) is related to lower SSSC and vice versa. This article highlights the role of base flow on sediment dynamics and provides a method to analyze it through a seasonal empirical model combining the influence of both Qb and Qs, which could be employed in other watersheds. A probabilistic method to examine the SSSC relationship with R and Q is also proposed. © 2019 by the authors
Natural infection of Aedes aegypti by Chikungunya and Dengue type 2 Virus in a transition area of north-northeast Brazil
Get PDFDengue fever, chikungunya, and Zika are diseases caused by viruses transmitted by Aedes aegypti and Aedes albopictus. In Brazil, the number of human infections is high, but few studies are performed in mosquito vectors. This study aimed to investigate the presence of Zika, Dengue and Chikungunya viruses in Ae. aegypti and Ae. albopictus from the municipalities of Alto Alegre, Caxias, Codó, and São Mateus do Maranhão, located in the state of Maranhão, Northeast Brazil. The mosquitoes were collected with a mechanical aspirator, identified, triturated, and then submitted to RNA extraction and RT-qPCR. The positive samples were confirmed by virus isolation and genome sequencing. Three hundred and forty-eight Ae. aegypti (176 males and 172 females) and 12 Ae. albopictus (eight males and four females) were collected and tested. Ae. aegypti was the only vector positive in two municipalities-Codó, with detection of Chikungunya virus (CHIKV) belonging to the East-Central-South African genotype, and in Caxias, with detection of Dengue virus (DENV)-2 belonging to the Asian/American genotype. The detection of CHIKV and DENV-2 is evidence that those viruses are maintained in arthropod vectors, and shows the epidemiological risk in the area for chikungunya cases and a possible increase of severe dengue cases, associated with the occurrence of dengue hemorrhagic fever. © 2019 by the authors
Qualidade fisiológica de sementes peletizadas de cubiu (Solanum sessiliflorum dunal)
Get PDFThe objective of this study was to evaluate the effect of different coating materials on the physiological quality of cubiu seeds. This was evaluated with three agglomerate materials (manioc starch, inert talc and dolomitic limestone) and two binder polymers (polyvinyl acetate and gum arabic) with 30% concentration, and artificial dye finishing. The experimental design was completely randomized, in factorial scheme 3 (agglomerates) x 2 (binders), and additional treatment (bare seeds/control), containing four replicates and experimental units of fifty seeds/ pellets. The seeds were evaluated for: yield; seed/pellet diameter; thousand seed weight; number of seeds per pellets; germination; germination speed index; mean germination time, seedling length; fresh and dry mass of the seedling and emergence. In general, pelletizing increased the weight and diameter of the propagation unit. The physical barrier applied to the seeds by pelletizing did not influence the germination, but delayed the germination rate concerning to bare seeds, and this effect was not observed in emergence seedling. The coating with dolomitic limestone and polyvinyl acetate presented the best results of germination and vigor. © 2019, Sociedade Brasileira de Fruticultura. All rights reserved
Estudo do Comportamento do Fluxo de Água Na Zona Saturada da Reserva Biológica do Cuieiras, Amazônia Central
Get PDFInformation on the behavior of underground flow from high to low altitudes in the Amazon region, in natural environments, as to velocity and base flow, is still incipient and does not reflect its current relevance related to water dynamics at different topographic levels. The behavior of water in the saturated soil zone, the groundwater flow from estimates of hydraulic conductivity in slope and shallow areas, under seasonal and interannual scale from 2003 to 2017, in the Cuieiras Biological Reserve in the Central Amazon to the north was analyzed. From the city of Manaus. Through piezometers distributed on site, the average values of hydraulic conductivity were estimated. High heterogeneity was observed with a minimum and maximum variation of 30mm / h and 511mm / h; higher flow velocity in locations with high conductivity and lower velocity in areas with low saturated soil hydraulic conductivity. At the level the level oscillated at a frequency of 0.10m to 0.60m; on the slope from 3m to 5m and on the plateau from 23m to 42m deep. In the basal flow, the shoal was slower and varied from 1.00 ± 4.20E-6m3/s. It is considered important that this result be explored to characterize complementary studies involving the transferability, transport of solutes, and underground and free aquifer recharge according to the topographic sequences of the region.As informações sobre o comportamento do fluxo subterrâneo de altas a baixas altitudes na região amazônica, em ambientes naturais, quanto à velocidade e ao fluxo de base, ainda são incipientes e não refletem sua relevância atual relacionadas a dinâmica da água em diferentes níveis topográficos. Analisou-se o comportamento da água na zona saturada do solo, o fluxo subterrâneo a partir de estimativas da condutividade hidráulica, em áreas de vertente e baixio, sob escala sazonal e interanual de 2003 a 2017, na reserva Biológica do Cuieiras na Amazônia Central ao norte da cidade de Manaus. Através de piezômetros distribuídos no local estimou-se os valores médios de condutividade hidráulica. Constatou-se alta heterogeneidade com variação de 30mm/h mínimo e máximo de 511mm/h; maior velocidade do fluxo em locais com alta condutividade e velocidade menor em áreas com baixa condutividade hidráulica saturada do solo. No baixio o nível oscilou numa frequência de 0,10m a 0.60m; na vertente de 3m a 5m e no platô de 23m a 42m de profundidade. O fluxo de base, no baixio, apresentou-se mais lento e variou de 1.00 ± 4.20E-6m3/s. Considera-se importante que seja explorado esse resultado para caracterização de estudos complementares que envolvam a trasmissividade, transporte de solutos, via subterrânea, e recarga de aquífero livres consoante às sequências topográficas da região
Nematofauna de piranha-vermelha Pygocentrus nattereri (Kner, 1958) (Characiformes: Serrasalmidae) da Amazonia, Brasil
Get PDFBetween March and October 2008, 355 specimens of Pygocentrus nattereri were collected from the lowland lakes of Central Amazonia, Brazil, to study their nematode fauna. A total of 1.116 specimens of Nematoda were collected, belonging to six species. Procamallanus (Spirocamallanus) inopinatus was the species with the highest parasite indices. Larvae of Anisakis sp. have zoonotic potential and were found parasitizing the intestine and liver of Pygocentrus nattereri. Some of these nematode species were new records for the host P. nattereri. The diversity of nematodes that use P. nattereri as a host indicates the important role of this fish species in the maintenance of these six nematode species in the lowland lakes of Central Amazonia. © 2019, Brazilain Coll Veterinary Parasitology. All rights reserved
A review of the Neotropical genus Amazobenna Penny, 1980 with description of a new species and description of the male of Amazobenna reticulata Penny, 1980 (Hemiptera: Fulgoromorpha: Cixiidae)
No full textA second species of the genus Amazobenna Penny, 1980, Amazobenna pennyi sp. nov., is described from the Brazil. The new species can be distinguished from Amazobenna reticulata Penny, 1980, the type species of the genus, by the coloration of the body and wing and by the characters of the male genitalia. The description of male of Amazobenna reticulata is also provided and morphology of male and female genitalia of the genus is discussed for the first time. Copyright © 2019 Magnolia Press
Mapping research on hydropower and sustainability in the Brazilian Amazon: advances, gaps in knowledge and future directions
No full textIn the last twenty years, multiple large and small hydroelectric dams have begun to transform the Amazonian region, spawning a growing volume of academic research across diverse disciplinary and interdisciplinary fields. In this article, we offer a critical review of recent research related to hydropower and sustainability with a focus on the Brazilian Amazon. We revisit the sustainability concept to include the contribution of various knowledge fields and perspectives for understanding, managing and making decisions about social-ecological systems transformed by dams. We conducted a literature review in Web of Science of academic publications centered in the past 5 years (2014–2019), on diverse aspects of hydropower planning, construction, operation and monitoring in the Brazilian Amazon. We present results of a co-occurrence network analysis of publications, highlighting bridging fields, network disconnections, and opportunities for interdisciplinary research. Finally, we report recent advances in the understanding and management of social-ecological systems in Amazonian watersheds, including biophysical, socio-economic, governance and development processes linked to hydropower planning and implementation. This review identifies knowledge gaps and future research directions, highlighting opportunities for improved communication among scientists, practitioners, decision-makers, indigenous peoples and local communities. © 2019 Elsevier B.V
Uma nova espécie de Coccoloba P. Browne (Polygonaceae) da Amazônia brasileira com folhas excepcionalmente grandes
Get PDFWe describe and illustrate a new species of Coccoloba (Polygonaceae), named Coccoloba gigantifolia, from the Brazilian Amazon. It resembles Coccoloba mollis Casar, but differs from the latter species by its much larger leaves in the fertile branches. The species has only been recorded in the Madeira River basin, in the states of Amazonas and Rondônia, in the central and southwestern Brazilian Amazon. The description was based on herbarium material, cultivated plants, and individual trees in their natural habitat. We provide illustrations, photographs, and an identification key with morphological characteristics that distinguish the new taxon from the other two related taxa of the Coccoloba sect. Paniculatae, as well as comments on the geographic distribution and conservation status of the species. © 2019, (publisher Name). All right reserved