22 research outputs found
Avaliação de diferentes doses de aflatoxina e fumonisina sobre os parùmetros reprodutivos de galos
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro TecnolĂłgico. Programa de PĂłs-Graduação em Engenharia QuĂmica.Este trabalho foi conduzido visando avaliar o efeito de Aflatoxina e Fumonisina no desempenho reprodutivo de galos, atravĂ©s de dietas especĂficas. Foram utilizados sessenta galos da linhagem Cobb 500, com aproximadamente 22 semanas, distribuĂdos em dois experimentos. Quarenta galos distribuĂdos num delineamento inteiramente casualizado constituĂdo por quatro tratamentos (quatro nĂveis de aflatoxina e fumonisina) foram alojados em quatro boxes de 10 aves cada (uma ave = uma repetição). Para estes animais foram avaliados o vigor dos espermatozĂłides, a morfologia espermĂĄtica e o peso dos testĂculos. Paralelamente, 20 galos foram alojados com 200 galinhas Cobb 500 e distribuĂdos em 20 boxes contendo cada um 10 galinhas e 1 galo, num delineamento inteiramente casualizado (quatro nĂveis de aflatoxina e fumonisina e cinco repetiçÔes). Para estes animais foi avaliado o percentual de ovos fĂ©rteis gerados em relação aos diferentes tratamentos aos quais os galos foram submetidos. Os nĂveis de micotoxinas desejados foram atingidos utlizando-se milho visivelmente atacado por fungos e previamente analisado, bem como atravĂ©s da suplementação de culturas fĂșngicas contendo aflatoxina e fumonisina. O perĂodo experimental consistiu de 96 dias, divididos num perĂodo 30 dias de adaptação das aves Ă s coletas de sĂȘmen e 46 dias para a coleta de dados. Os tratamentos foram comparadas pelo teste de Tukey. NĂŁo foram verificadas diferenças significativas entre os tratamentos quando avaliados o vigor espermĂĄtico, morfologia espermĂĄtica e peso dos testĂculos dos animais utilizados nos experimentos. Para a anĂĄlise de fertilidade em ovos, os dados mostraram comportamento inverso ao esperado, mostrando melhor resultado para os tratamentos de nĂvel 2 e 4 de micotoxinas adicionadas. Para este parĂąmetro nĂŁo foi possĂvel um resultado mais conclusivo, pois resultados de mesma significĂąncia foram verificados para tratamentos onde foram utilizados nĂveis de toxinas bastante diferentes. Os resultados obtidos neste trabalho indicaram que os teores de micotoxinas utilizados nĂŁo afetaram os Ăndices de fertilidade e caracterĂsticas do sĂȘmen de Galos Cobb 500
Identifying critical regions in small-world marine metapopulations.
The precarious state of many nearshore marine ecosystems has prompted the use of marine protected areas as a tool for management and conservation. However, there remains substantial debate over their design and, in particular, how to best account for the spatial dynamics of nearshore marine species. Many commercially important nearshore marine species are sedentary as adults, with limited home ranges. It is as larvae that they disperse greater distances, traveling with ocean currents sometimes hundreds of kilometers. As a result, these species exist in spatially complex systems of connected subpopulations. Here, we explicitly account for the mutual dependence of subpopulations and approach protected area design in terms of network robustness. Our goal is to characterize the topology of nearshore metapopulation networks and their response to perturbation, and to identify critical subpopulations whose protection would reduce the risk for stock collapse. We define metapopulation networks using realistic estimates of larval dispersal generated from ocean circulation simulations and spatially explicit metapopulation models, and we then explore their robustness using node-removal simulation experiments. Nearshore metapopulations show small-world network properties, and we identify a set of highly connected hub subpopulations whose removal maximally disrupts the metapopulation network. Protecting these subpopulations reduces the risk for systemic failure and stock collapse. Our focus on catastrophe avoidance provides a unique perspective for spatial marine planning and the design of marine protected areas
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Identifying critical regions in small-world marine metapopulations.
The precarious state of many nearshore marine ecosystems has prompted the use of marine protected areas as a tool for management and conservation. However, there remains substantial debate over their design and, in particular, how to best account for the spatial dynamics of nearshore marine species. Many commercially important nearshore marine species are sedentary as adults, with limited home ranges. It is as larvae that they disperse greater distances, traveling with ocean currents sometimes hundreds of kilometers. As a result, these species exist in spatially complex systems of connected subpopulations. Here, we explicitly account for the mutual dependence of subpopulations and approach protected area design in terms of network robustness. Our goal is to characterize the topology of nearshore metapopulation networks and their response to perturbation, and to identify critical subpopulations whose protection would reduce the risk for stock collapse. We define metapopulation networks using realistic estimates of larval dispersal generated from ocean circulation simulations and spatially explicit metapopulation models, and we then explore their robustness using node-removal simulation experiments. Nearshore metapopulations show small-world network properties, and we identify a set of highly connected hub subpopulations whose removal maximally disrupts the metapopulation network. Protecting these subpopulations reduces the risk for systemic failure and stock collapse. Our focus on catastrophe avoidance provides a unique perspective for spatial marine planning and the design of marine protected areas