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Perulernaea gamitanae (Crustacea: Lerneaidae) en juveniles de Colossoma macropomum (Characiformes: Sarrasalmidae) en cultivo semi-intensivo en Loreto, Perú
Get PDFThe aim of this study was to determine the presence of the copepod Perulernaea gamitanae in juveniles of Colossoma macropomum and to relate the abundance of the parasite with the length and weight of the hosts. Thirty specimens of 29.1 ± 2.8 cm of total length and 506.3 ± 124.6 g of body weight from a semi-intensive fish farm in Maynas, Loreto (Peru) were evaluated. It was collected 120 individuals of P. gamitanae located in the buccal cavity and in the cartilages of the gills. The prevalence was 90%, the mean intensity was 4.4 parasites/infested fish, the average abundance was 4 parasites/fish, with an intensity range of 1 to 10 parasites/fish. The abundance of this copepod was related to the length and weight of the host. This is the second record of P. gamitanae in C. macropomun in fish farms in the Peruvian Amazon. © 2019 Universidad Nacional Mayor de San Marcos. All rights reserved
Alternative functional trajectories along succession after different land uses in central Amazonia
No full textThe recovery capacity and the successional pathways of tropical forests after anthropogenic disturbance vary considerably and may depend on prior land-use type and intensity. It is still unclear if forests subjected to high intensity impact, such as periodically burned pastures, are capable of restoring their original functional properties. This study analysed the functional trait dynamics of the dominant species in successional trajectories following two land uses, pasture or clear-cut, north of Manaus. Fourteen years of demographic data from the Biological Dynamics of Forest Fragments Project were used to determine the dominant species of the two successional trajectories, for which leaf area, leaf dry mass content, specific leaf area and wood density were collected, whereas seed mass was obtained from literature. Community weighted mean of each trait was weighted by basal area determined annually along succession. Prinicpal components analysis was used to analyse the extension and direction of the functional trajectories of plots. Forests regenerating from pastures increased in wood density through successional time, but other traits did not change significantly. Succession after clear-cut exhibited increasing leaf dry mass content and seed mass, and decreasing leaf area over time, but no change in wood density. Functional trajectories of plots after clear-cut were more extensive and directional than those of pasture-derived plots. Synthesis and applications. We demonstrate how central Amazonian secondary forests subjected to different land uses show differences in functional trait trajectories, in ways parallel to previously shown changes in biomass, floristic diversity and forest structure. These results indicate that natural recovery of forest functional traits is affected by prior land-use history, with implications for management and restoration. Thus, natural recovery of forests on abandoned pastures is much slower than clear-cuts, even though seed sources from mature forests are very close to these areas, and the former may need intervention to counteract the diverted succession. © 2019 The Authors. Journal of Applied Ecology © 2019 British Ecological Societ
Diversity, composition and biomass of native vascular plants regenerating under Acacia mangium Will. plantations in northern Amazonia
Get PDFIt is imperative that studies can be developed to assess the role of homogeneous tree plantations in biodiversity conservation and the ability to store atmospheric carbon. This study aimed to evaluate the effects of Acacia mangium Will. plantations established in areas originally occupied by savanna (locally termed “lavrado”) on the establishment success of vascular plants, by analyzing three attributes of the community—diversity, composition and biomass. All plants with base diameter ≥ 1 cm were measured in 28 0.05-ha plots (11 plots allocated in natural areas of “lavrado” and 17 under A. mangium plantations). Species diversity was much higher in A. mangium plantation than in the natural areas of “lavrado”. There was a clear floristic differentiation between A. mangium and “lavrado”, with high density of forest species and low density of “lavrado” species growing under A. mangium plantations. “Lavrado” plots presented high floristic similarity, but plots under A. mangium plantations were far less similar, indicating a more heterogeneous vegetation. Biomass of vascular plants in A. mangium plantations was about one-fifth of that found in natural “lavrado” sites, but in “lavrado” 92.6% of the total biomass was allocated in only two species, whereas in A. mangium plantation two species comprised only 43% of the total biomass. In A. mangium plantation, species classified as forest species and typical “lavrado” species accounted for 72.8% and 27.2% of total biomass, respectively. Our results showed that A. mangium plantations resulted in high alpha and beta plant diversity due to the invasion of alien forest species. Also, biomass of “lavrado” species in plantations was smaller and species relative abundances completely different from natural “lavrados”. Therefore, we conclude that forest plantations established in savannas cannot be used to meet conservationist purposes. © 2019, Botanical Society of Sao Paulo
Persistent effects of fragmentation on tropical rainforest canopy structure after 20 yr of isolation
No full textAssessing the persistent impacts of fragmentation on aboveground structure of tropical forests is essential to understanding the consequences of land use change for carbon storage and other ecosystem functions. We investigated the influence of edge distance and fragment size on canopy structure, aboveground woody biomass (AGB), and AGB turnover in the Biological Dynamics of Forest Fragments Project (BDFFP) in central Amazon, Brazil, after 22+ yr of fragment isolation, by combining canopy variables collected with portable canopy profiling lidar and airborne laser scanning surveys with long-term forest inventories. Forest height decreased by 30% at edges of large fragments (>10 ha) and interiors of small fragments (<3 ha). In larger fragments, canopy height was reduced up to 40 m from edges. Leaf area density profiles differed near edges: the density of understory vegetation was higher and midstory vegetation lower, consistent with canopy reorganization via increased regeneration of pioneers following post-fragmentation mortality of large trees. However, canopy openness and leaf area index remained similar to control plots throughout fragments, while canopy spatial heterogeneity was generally lower at edges. AGB stocks and fluxes were positively related to canopy height and negatively related to spatial heterogeneity. Other forest structure variables typically used to assess the ecological impacts of fragmentation (basal area, density of individuals, and density of pioneer trees) were also related to lidar-derived canopy surface variables. Canopy reorganization through the replacement of edge-sensitive species by disturbance-tolerant ones may have mitigated the biomass loss effects due to fragmentation observed in the earlier years of BDFFP. Lidar technology offered novel insights and observational scales for analysis of the ecological impacts of fragmentation on forest structure and function, specifically aboveground biomass storage. © 2019 by the Ecological Society of Americ
Thermal requirements of seed germination of ten tree species occurring in the western Brazilian Amazon
No full textRegeneration from seed affects species assembly in plant communities, and temperature is the most important environmental factor controlling the germination process. Thermal dependence of seed germination is thus associated with species occurrence in an ecosystem. Hence, we aimed to investigate the role of temperature on seed germination of ten tree species from the western Brazilian Amazon. Seeds were collected in the state of Rondônia, Brazil, and set to germinate under constant temperatures ranging from 10 to 40°C in germination chambers. We calculated germination capacity (G%), germination rate (GR50, reciprocal of germination time), and thermal parameters, such as cardinal temperatures and thermal time requirements. Most species had a large range of temperatures showing G% ≥80%, with optimal temperature varying from 20 to 40°C. Base temperature ranged from 6 to 12°C and ceiling temperatures were mainly >40°C. Astronium lecointei and Parkia nitida showed high germination capacity under temperatures of 35-40°C, while germination of Theobroma cacao dropped from 100% to zero under temperatures between 37 and 40°C. The climax species Cedrela fissilis had the slowest germination time (10 days) and highest thermal time requirement, while seeds of Enterolobium schomburgkii (a late-successional species) germinated within the first day of the experiment. Rapid recruitment of Amazon species could be favoured with treefall disturbance, which increases temperatures in the understory, but sharp limits might be found in the supra-optimal range of temperatures. Such patterns might indicate different regeneration strategies in the tropical rainforest, providing important information regarding seed germination among Amazon species. © 2019 Cambridge University Press
Efectividade simbiótica de isolados de rizóbios em caupi (Vigna unguiculata L. walp) em latossolo ácido e álico na Amazônia
No full textFirst record of Anelosimus jucundus (O. Pickard-Cambridge, 1896) (Araneae, Theridiidae) in the state of Ceara, Brazil
Get PDFWe present the first record for Anelosimus jucundus O. Pickard-Cambridge, 1896 for the state of Ceará, Brazil. We collected 22 individuals in three different ecosystems: (1) Mangrove swamps, (2) Caatinga-type desert vegetation, and (3) Montane semi-deciduous tropical forest. We corrected the misinformation of Levi’s 1963 Ceará record, was actually from the state of Pernambuco. Anelosimus jucundus presents a wide altitudinal distribution, which indicates that this species can tolerate a variety climatic conditions and can colonize a variety of sites with different vegetation. © 2019, Pensoft Publishers. All rights reserved
Multi-focus image fusion for bacilli images in conventional sputum smear microscopy for tuberculosis
No full textBright-field microscopy of sputum samples is still the most widely used Tuberculosis (TB) diagnostic method in countries facing a high incidence of TB. However, this diagnostic method, because it is a visual analysis, requires attention and training of those who perform it, and presents high intra- and inter-observed variation. As a result, many research groups are working on methods of automatic detection of bacilli, aiming to automate this process. The fact that not all of the bacilli present in the examined microscope field are in focus increases the challenge faced by researchers in obtaining automatic methods of detecting bacilli. Fusion images can be a means of overcoming this problem, combining multiple images, from the same field, with diverse focuses into a single focused one. In this paper, we present a multi-focus image fusion method applied to conventional sputum smear microscopy images. The goal is to establish the best method to obtain an extended focus microscopy image where all bacilli present in the field are in focus. The proposed method was compared with three other techniques from the literature by using Variance and Multichannel QAB/F metrics. The proposed method exhibited the best balance of quality evidence (focus and preservation of information). © 201
Efeito da maturação gonadal no padrão de preferências de fêmeas por descargas de machos coespecíficos em um Peixe Elétrico Amazônico
Get PDFThe mechanism by which individuals choose among potential reproductive partners imposes sexual selection through variations in secondary sexual characters on the chosen sex. The secondary sexual characters are represented by conspicuous ornaments and often act as honest contents of the individual's quality. In weakly electric fish, intraspecific communication occurs through the electric organ discharges (EOD) and, during the reproductive period, EODs become sexually dimorphic in most genera. Higher intensity of sexual dimorphism in EODs suggests the presence of sexual selection through EOD parameters. In our study, we investigated the preference of mature females for EOD parameters produced by males. First, we investigated the sexual dimorphism of individuals between the non-reproductive and reproductive periods and, subsequently, the preference of females for EODs through non-forced preference tests and analysis of EOD parameters. For this, a two-choice aquarium was used, divided into three main zones: Neutral Zone (NZ), two Confinement Zones (CZs) and two Preference Zones (PZs). Each test was performed with a triad of individuals: one female in NZ with access to both PZs and two potentially preferred individuals confined in a CZ each. Female preference was measured by the time that females occupied each PZ, which was attributed to the individual occupying the CZs. Our preference results showed that both immature and mature females performed statistically significant choices by individuals but differed in choice frequency. While immature females generally occupied for more time one of the PZs, most of the mature females made assertive choices for one of the males (one PZ). EOD parameters revealed marked seasonality in the sexual dimorphism of EODs caused by gonadal maturation in males, and EOD patterns from mature males corresponding to female preferences. The observed spontaneous choices by females were related to the variation in EOD parameters, between two well defined patterns. The preferred pattern proved to be substantially different from the non-preferred (rejected) in eight parameters. These parameters may indicate quality attributes important in the reproductive context to females. Within those, the duration of EOD was already shown to relate to the size of the individual and the longer duration of the second phase is considered a conspicuous ornament in males used in sexual selection by females. This study was the first to characterize the EOD produced by males and females from this species, which corresponded to non-breeding and breeding periods, uncovering that females base their choice on EOD characteristics from males with well-defined patterns, even outside the breeding period, and more markedly during gonadal maturation, corroborating the role of sexual selection in the evolution of EODs in this group of electric fish.O mecanismo de escolha por parceiros reprodutivos impõe a seleção sexual através de variações em caracteres sexuais secundários no sexo escolhido. Os caracteres sexuais secundários podem se expressar através de ornamentos conspícuos, atuando frequentemente como índices confiáveis de aptidão do indivíduo. Em peixes elétricos de descarga fraca, a comunicação intraespecífica ocorre através de descargas do órgão elétrico (DOE) podendo se tornar sexualmente dimórficas na maioria dos gêneros durante o período reprodutivo. A acentuação do dimorfismo sexual nas DOEs sugere a presença de seleção sexual através de características elétricas da DOE. Neste estudo foi investigado a preferência de fêmeas maduras por parâmetros específicos das DOEs de machos. Primeiramente, foi investigado o dimorfismo sexual nas DOEs de indivíduos entre estágio não reprodutivo e reprodutivo e, posteriormente, a preferência de fêmeas pelas DOEs por meio de testes de preferência não forçada e análise dos parâmetros das DOEs. Para isso, foi utilizado um aquário de duas escolhas, dividido em três zonas principais: Zona Neutra (ZN), duas Zonas da Confinamentos (ZCs) e duas Zonas de Preferência (ZPs). Cada teste foi realizado com uma tríade de indivíduos: uma fêmea na ZN com acesso as ZPs e dois indivíduos potencialmente escolhidos confinados em uma ZC cada um. A preferência da fêmea foi contabilizada pela quantificação do tempo de ocupação de cada ZP e atribuída ao indivíduo que ocupava a ZC correspondente. Em nossos resultados de preferência, tanto fêmeas não maduras quanto maduras escolheram significativamente um dos indivíduos, mas diferiram entre si na frequência de escolha. As fêmeas não maduras, em geral, ocuparam com maior frequência a ZPs relacionada a um macho, mas não diferindo muito o tempo de ocupação entre as ZPs. Enquanto a maioria das fêmeas maduras realizaram escolhas assertivas por algum macho, diferindo marcadamente no tempo de permanência entre ZPs. Os resultados das análises dos parâmetros de DOE, evidenciaram sazonalidade no dimorfismo sexual na DOE, ocasionado pela maturação gonadal em machos e padrões de DOE em machos maduros correspondentes ao padrão de preferência das fêmeas. De fato, as escolhas espontâneas das fêmeas puderam ser relacionadas a dois padrões principais de DOE e o padrão preferido se mostrou consideravelmente diferente do não preferido em oito parâmetros. Estes parâmetros podem indicar às fêmeas atributos de aptidão importantes no contexto reprodutivo. Dentre eles, a duração da DOE já foi relacionada ao tamanho do indivíduo e a maior duração da segunda fase pode ser considerada um ornamento conspícuo variável em machos utilizado na seleção sexual por fêmeas. Este estudo foi o primeiro a caracterizar a DOE emitida por machos e fêmeas desta espécie compatíveis aos períodos não reprodutivo e reprodutivo, evidenciando que as fêmeas utilizam características das DOEs com padrões bem definidos na escolha de machos mesmo na estação não reprodutiva, e mais acentuadamente durante o estágio de maturação gonadal, corroborando o papel da seleção sexual na evolução das DOEs neste grupo de peixes elétricos
