196 research outputs found

    Community-based population recovery of overexploited Amazonian wildlife

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    The Amazon Basin experienced a pervasive process of resource overexploitation during the 20th-century, which induced severe population declines of many iconic vertebrate species. In addition to biodiversity loss and the ecological consequences of defaunation, food security of local communities was relentlessly threatened because wild meat had a historically pivotal role in protein acquisition by local dwellers. Here we discuss the urgent need to regulate subsistence hunting by Amazonian semi-subsistence local communities, which are far removed from the market and information economy. Following positive examples from community-based management of aquatic and terrestrial resources, we advocate that hunting practices, based on modern scientific principles firmly grounded in population ecology, represent a strong window of opportunity to recover viable populations of previously overexploited wildlife

    Population recovery, seasonal site fidelity and daily activity of pirarucu (Arapaima spp.) in an Amazonian floodplain mosaic

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    1. Pirarucu (Arapaima spp.) are the world's largest scaled freshwater fish, reaching 3 m in length and >200 kg in weight. Historical overfishing has devastated populations of this remarkable fish across Amazonian floodplains, but community‐based management programmes are now stimulating the recovery of wild populations. 2. Pirarucu have evolved a unique set of life history traits, some of which have important implications for population management. Individuals exhibit lateral annual migration patterns during the prolonged annual flood pulse, entering flooded forests to reproduce and forage. During this period, although managed fish stocks become less monopolisable by local communities responsible for managing protected lakes, pirarucu can occupy and reproduce in new environments and thus potentially contribute to population recovery. 3. Here, we show a strong pattern of pirarucu (Arapaima cf. gigas) population recovery under community‐based management in an area along the Juruá River, in western Brazilian Amazonia. We show evidence of population recovery even outside formal protected areas, reinforcing the suitability of pirarucu community‐based management as a powerful tool for both biodiversity conservation and the improvement of local livelihoods. We also show pirarucu movements across a floodplain mosaic—including lakes, the main river channel, tributary streams, and flooded forests—during the wet season. 4. Our results support evidence of site fidelity among migrating pirarucu, justifying the high effort invested by local communities in seasonally protecting lakes from poachers and illegal fishers. Finally, restricted daily movement patterns by pirarucu support the suitability of population estimates based on day‐time counts because the chance of double counting is substantially reduced during the day when these counts are conducted. We highlight the strong suitability of this species for community‐based management, since they can: (1) replenish new environments during the wet season through migration and possibly also reproduction; and (2) be efficiently harvested during the dry season, delivering social and ecological benefits at large spatial scales. 5. Positive examples of fisheries management, which align biodiversity conservation and social development, are important for building optimism, and influencing local and international stakeholders. Our study shows how engaging and empowering local communities to help monitor the movement ecology of target species can be an effective strategy to support the sustainable management of aquatic resources in tropical environments

    Markedly divergent tree assemblage responses to tropical forest loss and fragmentation across a strong seasonality gradient

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    We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shadetolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentationinduced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide

    Reactive PLIF method for characterisation of micromixing in continuous high-throughput chemical reactors

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    This work aimed to test and optimise reactive Planar Laser-Induced Fluorescence (PLIF) methods for the visualisation of the micromixing regions in chemical reactors using standard PLIF and Particle Image Velocimetry (PIV) equipment with the laser source 512 nm. Two methods were tested: (i) an acid–base reaction with fluorescein as the reaction-sensitive tracer and (ii) Fenton’s reaction, with Rhodamine B as the reaction tracer. Both test-reactions were studied in stopped-flow equipment to define suitable operational conditions, namely the chemical composition of the inflow streams, the concentration of reagents and fluorophore, and suitable excitation light wavelength. The visualisation of the micromixing regions was tested in a continuous flow reactor with a T-jet geometry. A laser light sheet emitted from an Nd:YAG laser illuminated the axial section of the demonstration reactor. The mixing dynamics and the reaction course were visualised with the acid–base reactive PLIF images. Fenton’s reactive PLIF method showed the overall distribution of mixing and reaction regions. The main contribution of this work is benchmarking two methods with costs that enable the visualisation of micromixing regions in continuous high-throughput reactors.publishe

    Characteristics of ash and particle emissions during bubbling fluidised bed combustion of three types of residual forest biomass

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    Combustion of residual forest biomass (RFB) derived from eucalypt (Eucalyptus globulus), pine (Pinus pinaster) and golden wattle (Acacia longifolia) was evaluated in a pilot-scale bubbling fluidised bed reactor (BFBR). During the combustion experiments, monitoring of temperature, pressure and exhaust gas composition has been made. Ash samples were collected at several locations along the furnace and flue gas treatment devices (cyclone and bag filter) after each combustion experiment and were analysed for their unburnt carbon content and chemical composition. Total suspended particles (TSP) in the combustion flue gas were evaluated at the inlet and outlet of cyclone and baghouse filter and further analysed for organic and elemental carbon, carbonates and 57 chemical elements. High particulate matter collection efficiencies in the range of 94-99% were observed for the baghouse, while removal rates of only 1.4-17% were registered for the cyclone. Due to the sand bed, Si was the major element in bottom ashes. Fly ashes, in particular those from eucalypt combustion, were especially rich in CaO, followed by relevant amounts of SiO2, MgO and K2O. Ash characteristics varied among experiments, showing that their inorganic composition strongly depends on both the biomass composition and combustion conditions. Inorganic constituents accounted for TSP mass fractions up to 40 wt%. Elemental carbon, organic matter and carbonates contributed to TSP mass fractions in the ranges 0.58-44%, 0.79-78% and 0.01-1.7%, respectively.publishe

    Characterization of phenolic compounds of OMW : toxicity and degradability by yeasts

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    The characterization of Olive Mill Wastewaters (OMW), focusing the phenolic compounds, is one of the aims of the present work. As a first approach to characterize the phenolic compounds of OMW, the extraction methods used were: a liquid-liquid extraction by acidified ethyl acetate and a solid-liquid extraction with acidified methanol. The analysis of these extracts by reversed phase liquid chromatography confirmed that hydroxytyrosol was the most abundant phenolic compound in OMW, and that this compound was more efficiently recovered by the solid-liquid extraction technique. It was also a goal of this work to study the phenolic compounds toxicity to some yeast strains. Among the phenolic compounds tested catechol is the most inhibitory one to the cells. The phenols degradation was quite difficult, particularly when more easily degradable carbon source is still present in the medium.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/AMB/69379/2006, SFRH/BD/27915/200

    Environmental policy at a critical junction in the Brazilian Amazon

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    Wholesale conversion of natural Amazonian ecosystems has been encouraged by Brazil’s extreme antienvironmental government, and historical forest loss explains municipal-scale voting prevalence. Embracing a new administration would strengthen local-to-regional governance, suppress illegal land grabbing, deforestation, logging, and gold mining, thereby protecting the world’s most species-rich forest domain and ensuring global sustainability

    Evolution of squeezed states under the Fock-Darwin Hamiltonian

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    We develop a complete analytical description of the time evolution of squeezed states of a charged particle under the Fock-Darwin Hamiltonian and a time-dependent electric field. This result generalises a relation obtained by Infeld and Pleba\'nski for states of the one-dimensional harmonic oscillator. We relate the evolution of a state-vector subjected to squeezing to that of state which is not subjected to squeezing and for which the time-evolution under the simple harmonic oscillator dynamics is known (e.g. an eigenstate of the Hamiltonian). A corresponding relation is also established for the Wigner functions of the states, in view of their utility in the analysis of cold-ion experiments. In an appendix, we compute the response functions of the FD Hamiltonian to an external electric field, using the same techniques as in the main text

    Effect of industrial and domestic ash from biomass combustion, and spent coffee grounds, on soil fertility and plant growth: experiments at field conditions

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    An experimental study was conducted at field conditions in order to evaluate the effect of application of ash from biomass combustion on some soil fertility characteristics and plant growth. Application of 7.5 Mg ha-1 industrial fly ash (IA), domestic ash (DA), and a 50:50 mix of domestic ash (DA) and spent coffee grounds (SCG) was made in different soil parcels. Lolium perenne seeds were sown and the grown biomass was harvested and quantified after 60 days. Soil samples from each parcel were also collected after that period and characterized. Both soil and grown biomass samples were analyzed for Ca, Mg, Na, K, P, Fe, Mn, Zn, and Al contents. Soil pH was determined before and after amendment. All applications rose significantly soil pH. Domestic ash, whether combined with coffee grounds or not, proved to be efficient at supplying available macronutrients Ca, Mg, K, and P to the soil and also reducing availability of Al (more than industrial ash). However, it inhibited plant growth, even more when combined with spent coffee grounds. As regards to elemental abundance in plant tissue, both domestic ash treatments reduced Ca and enhanced Al contents, unlike industrial ash, which proved less harmful for the load applied in the soil. Hence, it was possible to conclude that application load should be a limiting factor for this management option for the studied materials.publishe

    Warfare-induced mammal population declines in Southwestern Africa are mediated by species life history, habitat type and hunter preferences

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    Civil wars often coincide with global biodiversity hotspots and have plagued the everyday reality of many countries throughout human history. However, how do civil wars affect wildlife populations? Are these impacts the same in savannah and forest environments? How persistent are the post-war consequences on wildlife populations within and outside conflict zones? Long-term monitoring programs in war zones, which could answer these questions, are virtually nonexistent, not least due to the risks researchers are exposed to. In this context, only a few methodologies can provide data on wild populations during war conflicts. We used local ecological knowledge to assess the main consequences of a prolonged civil war (1975-2002) in Southwestern Africa on forest and savannah mammals. The post-war abundance in 20 of 26 (77%) mammal species considered in this study was lower in open savannah compared to the closed-canopy forest environments, with some species experiencing a decline of up to 80% of their pre-war baseline abundance. Large-bodied mammals were preferred targets and had been overhunted, but as their populations became increasingly depleted, the size structure of prey species gradually shifted towards smaller-bodied species. Finally, we present a general flow diagram of how civil wars in low-governance countries can have both positive and negative impacts on native wildlife populations at different scales of space and time
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