843 research outputs found

    Modelling the spread of American foulbrood in honeybees

    Get PDF
    We investigate the spread of American foulbrood (AFB), a disease caused by the bacterium Paenibacillus larvae, that affects bees and can be extremely damaging to beehives. Our dataset comes from an inspection period carried out during an AFB epidemic of honeybee colonies on the island of Jersey during the summer of 2010. The data include the number of hives of honeybees, location and owner of honeybee apiaries across the island. We use a spatial SIR model with an underlying owner network to simulate the epidemic and characterize the epidemic using a Markov chain Monte Carlo (MCMC) scheme to determine model parameters and infection times (including undetected ‘occult’ infections). Likely methods of infection spread can be inferred from the analysis, with both distance- and owner-based transmissions being found to contribute to the spread of AFB. The results of the MCMC are corroborated by simulating the epidemic using a stochastic SIR model, resulting in aggregate levels of infection that are comparable to the data. We use this stochastic SIR model to simulate the impact of different control strategies on controlling the epidemic. It is found that earlier inspections result in smaller epidemics and a higher likelihood of AFB extinction

    Shrimp ponds lead to massive loss of soil carbon and greenhouse gas emissions in northeastern Brazilian mangroves

    Get PDF
    Mangroves of the semiarid Caatinga region of northeastern Brazil are being rapidly converted to shrimp pond aquaculture. To determine ecosystem carbon stocks and potential greenhouse gas emissions from this widespread land use, we measured carbon stocks of eight mangrove forests and three shrimp ponds in the Acaraú and Jaguaribe watersheds in Ceará state, Brazil. The shrimp ponds were paired with adjacent intact mangroves to ascertain carbon losses and potential emissions from land conversion. The mean total ecosystem carbon stock of mangroves in this semiarid tropical landscape was 413 ± 94 Mg C/ha. There were highly significant differences in the ecosystem carbon stocks between the two sampled estuaries suggesting caution when extrapolating carbon stock across different estuaries even in the same landscape. Conversion of mangroves to shrimp ponds resulted in losses of 58%–82% of the ecosystem carbon stocks. The mean potential emissions arising from mangrove conversion to shrimp ponds was 1,390 Mg CO2e/ha. Carbon losses were largely from soils which accounted for 81% of the total emission. Losses from soils \u3e 100 cm in depth accounted for 33% of the total ecosystem carbon loss. Soil carbon losses from shrimp pond conversion are equivalent to about 182 years of soil carbon accumulation. Losses from mangrove conversion are about 10-fold greater than emissions from conversion of upland tropical dry forest in the Brazilian Caatinga underscoring the potential value for their inclusion in climate change mitigation activities

    Complex transboundary movements of marine megafauna in the Western Indian Ocean

    Get PDF
    Transboundary marine species have an increased risk of overexploitation as management regimes and enforcement can vary among states. The complex geopolitical layout of exclusive economic zones (EEZs) in the Western Indian Ocean (WIO) introduces the potential for migratory species to cross multiple boundaries, consequently a lack of scientific data could complicate regional management. In the current study, we highlight both the relative lack of spatial data available in the WIO, and the prevalence of transboundary movements in species that have previously been studied in the region. Five tiger sharks Galeocerdo cuvier were tracked with near real‐time positioning (SPOT) satellite tags to determine individual shark movements relative to EEZs within the WIO. Concurrently, a literature search was performed to identify all satellite telemetry studies conducted to date in the WIO for marine megafaunal species, and the results compared to global satellite telemetry effort. Finally, the satellite tracks of all marine species monitored in the WIO were extracted and digitized to examine the scale of transboundary movements that occur in the region. Tiger sharks exhibited both coastal and oceanic movements, with one individual crossing a total of eight EEZs. Satellite telemetry effort in the WIO has not matched the global increase, with only 4.7% of global studies occurring in the region. Species in the WIO remained within the EEZ in which they were tagged in only three studies, while all other species demonstrated some level of transboundary movement. This study demonstrates the lack of spatial data available for informed regional management in an area where transboundary movements by marine megafauna are highly prevalent. Without more dedicated funding and research, the rich biodiversity of the WIO is at risk of overexploitation from the diverse threats present within the various political regions

    Benthic habitat modelling and mapping as a conservation tool for marine protected areas: A seamount in the western Mediterranean

    Get PDF
    1. An ecologically representative, well‐connected, and effectively managed system of marine protected areas (MPAs) has positive ecological and environmental effects as well as social and economic benefits. Although progress in expanding the coverage of MPAs has been made, the application of management tools has not yet been implemented in most of these areas. 2. In this work, distribution models were applied to nine benthic habitats on a Mediterranean seamount within an MPA for conservation purposes. Benthic habitat occurrences were identified from 55 remotely operated vehicle (ROV) transects, at depths from 76 to 700 m, and data derived from multibeam bathymetry. Generalized additive models (GAMs) were applied to link the presence of each benthic habitat to local environmental proxies (depth, slope, backscatter, aspect, and bathymetric position index, BPI). 3. The main environmental drivers of habitat distribution were depth, slope, and BPI. Based on this result, five different geomorphological areas were distinguished. A full coverage map indicating the potential benthic habitat distribution on the seamount was obtained to inform spatial management. 4. The distribution of those habitats identified as vulnerable marine ecosystems (VMEs) was used to make recommendations on zonation for developing the management plan of the MPA. This process reveals itself as an appropriate methodological approach that can be developed in other areas of the Natura 2000 marine networkEn prensa1,92

    When enough should be enough: Improving the use of current agricultural lands could meet production demands and spare natural habitats in Brazil

    Get PDF
    Providing food and other products to a growing human population while safeguarding natural ecosystems and the provision of their services is a significant scientific, social and political challenge. With food demand likely to double over the next four decades, anthropization is already driving climate change and is the principal force behind species extinction, among other environmental impacts. The sustainable intensification of production on current agricultural lands has been suggested as a key solution to the competition for land between agriculture and natural ecosystems. However, few investigations have shown the extent to which these lands can meet projected demands while considering biophysical constraints. Here we investigate the improved use of existing agricultural lands and present insights into avoiding future competition for land. We focus on Brazil, a country projected to experience the largest increase in agricultural production over the next four decades and the richest nation in terrestrial carbon and biodiversity. Using various models and climatic datasets, we produced the first estimate of the carrying capacity of Brazil's 115 million hectares of cultivated pasturelands. We then investigated if the improved use of cultivated pasturelands would free enough land for the expansion of meat, crops, wood and biofuel, respecting biophysical constraints (i.e., terrain, climate) and including climate change impacts. We found that the current productivity of Brazilian cultivated pasturelands is 32–34% of its potential and that increasing productivity to 49–52% of the potential would suffice to meet demands for meat, crops, wood products and biofuels until at least 2040, without further conversion of natural ecosystems. As a result up to 14.3 Gt CO2 Eq could be mitigated. The fact that the country poised to undergo the largest expansion of agricultural production over the coming decades can do so without further conversion of natural habitats provokes the question whether the same can be true in other regional contexts and, ultimately, at the global scale

    Traditional Tropical Root Crop Technology: Some Interactions with Modern Science

    Get PDF
    RESUMEN Tecnología tradicional de las cosechas raiceras en los trópicos: ciertas interacciones con la ciencia moderna En la humedad tropical, las cosechas raiceras tales como mandioca, ñame y batata, junto con varias cosechas de rafíces aroides, son muy preferidas a los céréales como alimentos corrientes, ya que son m´s eficaces desde el punto de vista alimenticio en estos ecosistemas. Se ha estimado que constituyen la dieta corriente de unos 400 a 500 millones de personas. Los científicos agrícolas han prestado muy poca atención a los problemas de almacenamiento y tratamiento posterior a la cosecha de estos productos, pero las sociedades tradicionales que tanto dependen de ellos han evolucionado unos sistemas muy eficaces, con recursos muy limitados. Estas sociedades suelen ser ecocéntricas en lugar de tecnocéntricas y podrían beneficiarse por interacción con la moderna technología, siempre y cuando esta última no domine ni destruya los sistemas tradicionales. SUMMARY In the humid tropics, root crops such as cassava, yams, sweet and white potatoes and a variety of aroid root crops are widely preferred to grains as staple foods, as they are often more efficient food producers under these ecosystems. They have been estimated to provide the staple food of some 400?500 mn people. Little attention has been given by agricultural scientists to the post?harvest storage and processing problems of these crop products, but traditional societies dependent on them have evolved effective systems, with very limited resources. These societies are usually ecocentric rather than technocentric, and could benefit by interaction with modern technology so long as this neither dominates nor destroys the traditional systems. RÉSUMÉ La technologie tradionnelle des cultures tropicales de racines alimentaires; quelques interactions avec la science moderne Sous les tropiques humides, les cultures de racines alimentaires telles que manioc, igname, patates et pommes de terre blanches ainsi qu'une diversité de cultures de racines aracées ont en grande mesure la préférence sur les graines en tant que nourriture de base, vu qu'elles sont souvent des productrices d'aliments plus efficaces sous ces écosystèmes. On a calculé qu'elles assurent la nourriture de base à environ 400 à 500 millions de personnes. Les techniciens agronomes se sont peu penchés sur les problèmes d'emmagasinage et de traitement des produits se ces récoltes, mais les sociétés traditionnelles qui en dépendent ont mis au point des systèmes efficaces, avec des ressources de plus limitées. Ces sociétés sont d'habitude écocentriques plutôt que tecnnocentriques, et pourraient bénéficier de l'interaction avec la technologie moderne pour autant que cette dernière ni domine ni détruise les systèmes traditionnels
    corecore