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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Fertilidade do solo como principal preditor da abundância de mamíferos herbívoros em ilhas fluviais do Rio Negro, Amazônia

Ferreira Neto, Gilson de Souza 28 June 2018 (has links)
Submitted by Jorge Cativo (jorge.cativo@inpa.gov.br) on 2018-08-23T16:14:09Z No. of bitstreams: 2 DISSERTAÇÃO_GILSON-NETO_1007.pdf: 3774554 bytes, checksum: 90eaf1e85836c7b1801ee42c8df658f3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-08-23T16:14:09Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO_GILSON-NETO_1007.pdf: 3774554 bytes, checksum: 90eaf1e85836c7b1801ee42c8df658f3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-06-28 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The key factors driving species distribution within fluvial island systems worldwide are poorly known. Previous studies have shown that herbivore abundance and proportion in the mammal assemblage can be indirectly influenced by soil fertility via production of nutritious fruits and leaves and higher ecosystem dynamics linked to vegetation growth on more productive soils.The goal of this study was to investigate which environmental (soil fertility, tree basal area, forest cover and distance from sampling point to nearest mainland) and anthropogenic factors (logging, distance from the sampling point to nearest human community) were most closely-linked to observed patterns of mammalian abundance and proportions of omnivorous and herbivorous mammals on fluvial islands of the Rio Negro, Amazonas State, Brazil. Several of these islands are located on the left bank of the river, and so receive nutrient-rich sediments from the Rio Branco. We expected that our chosen environmental and anthoropogenic factors could predict island mammalian abundance patterns. We used camera traps to examine this, surveying 49 sampling sites across 60 days when water levels were seasonally low.We calculated the proportion of herbivorous and omnivorous mammals per site, and assayed their relationships to predictor variables with a series of generalized linear models (GLM). As expected, the number of records was low on all studied fluvial islands, compared with upland terra-firme studies. In 70,560 sampling hours we obtained 126 independent camera trap records, for a total of 11 mammal species. Total mammal abundance and proportion of the generalist omnivore Didelphis marsupialis was not affected by our chosen environmental and antropic variables. However, soil fertility played a central role in determining the proportion of herbivorous species.Thus, gradients of soil fertility can help to explain herbivore distributions on riverine islands, and define crucial areas for conservation and future restoration.Additionally, logging, distance to the nearest human community and to the mainland had a positive effect, and forest cover a negative effect, on the proportion of herbivorous mammals, but did not affect generalist omnivorous species. Therefore, results suggest that island soil fertility can differentialy impact proportions of mammals from the same feeding guild. / Os principais mecanismos que regulam a distribuição das espécies em ilhas fluviais são pouco conhecidos. Entender como os ciclos biogeoquímicos afetam a biosfera é um fator-chave para a compreensão do funcionamento dos ecossistemas. Na Amazônia, em uma escala regional, poucos estudos investigaram como a fertilidade do solo pode influenciar a abundância de mamíferos. Estudos prévios têm demonstrado que os mamíferos herbívoros podem ser indiretamente influenciados pela fertilidade do solo por meio de maior investimento das plantas em frutos e maior qualidade nutricional de folhas e frutos. A maioria desses estudos compararam extremos de gradientes ambientais (terra-firme e várzea e Amazônia sentido lesteoeste). Neste trabalho objetivamos investigar como a variação pequena de nutrientes encontrada nos solos, e adicionalmente outros aspectos da paisagem e fatores antrópicos, em ilhas fluviais, podem afetar as assembleias de mamíferos. A nossa expectativa era de que a fertilidade do solo, área basal de árvores, área florestada e distância do ponto de amostragem para a comunidade humana mais próxima influenciassem positivamente, enquanto que a exploração madeireira nestes ambientes e distância do ponto de amostragem a áreas de terra firme influenciassem negativamente a abundância total de mamíferos e proporção de herbívoros. Ainda, para espécies generalistas e onívoras estas relações seriam nulas. Os dados de abundancia relativa das espécies de mamíferos foram estimados utilizando 49 armadilhas fotográficas espaçadas cerca de 2km umas das outras no arquipélago, as quais operaram 24 horas durante 60 dias de amostragem. As relações entre as variáveis preditoras e a abundância relativa foram investigadas por uma série de modelos lineares generalizados (GLM). A espécie onívora Didelphis marsupialis contabilizou 60% dos registros totais de mamíferos. Nenhuma das variáveis preditoras, tanto ambientais quanto antrópicas foram capazes de explicar a abundância total de indivíduos e a proporção de Didelphis marsupialis na assembleia. Por outro lado, ao considerar somente as espécies herbívoras nas análises, a fertilidade do solo foi a variável explicativa com o maior poder preditivo e influenciou positivamente a proporção de mamíferos herbívoros. Os resultados deste trabalho indicam que a fertilidade do solo, em ilhas fluviais que recebem diferentes aportes de nutrientes, afeta de forma diferencial a proporção de indivíduos dentro de grandes agrupamentos taxonômicos, como os mamíferos terrestres.
2

Sero-prevalence of brucellosis in sheep and springbok (Antidorcas marsupialis) in the Karas Region of Namibia

Madzingira, Oscar 09 July 2013 (has links)
Game farming developed in Namibia over the years as a result of constraints associated with livestock farming such as diseases and profitability. The development of this industry has brought livestock and game species into close contact. In the Karas Region, a major sheep producing area, sheep and springbok are reared together on commercial farms. The rearing of these species in close proximity may result in crosstransmission of zoonotic diseases such as brucellosis, enabling such diseases to enter the human population through meat and other livestock products. Game species may complicate the control of brucellosis by acting as reservoirs of infection after the disease has been controlled in sheep. Brucellosis due to B. melitensis has been reported in Namibia as a cause of reproductive failure in sheep. An outbreak of brucellosis occurred xvi in 2009 affecting sheep, goats and humans on a farm in the adjacent Hardap Region. Brucellosis outbreaks in sheep have the potential to disrupt Namibia’s foreign currency earning as the sheep industry contributes greatly to the economy of the country. This aim of the study was to estimate the prevalence of Brucella (B. melitensis, B. abortus, B. ovis).infections in sheep and springbok in the Karas Region and to find out if the outbreak of brucellosis which occurred in the Hardap Region in 2009 had spread to the Karas Region. Two experimental designs were used in this study. The first was a retrospective analysis of brucellosis testing results from 2008-2010 to indicate probable prevalence and to identify positive farms for follow-up sampling in sheep and springbok. Serological testing results of sera (n=22994) collected from 762 farms between 2008 and 2010 were analyzed and used to estimate apparent brucellosis prevalence. A total of 472 sheep sera and nine springbok sera were collected from eight farms that tested positive for Brucella antibodies between 2008 and 2010. The second part of the study was a prospective serological study in sheep and springbok reared together; sheep in the Tses and Berseba communal areas and in culled ewes at the regional abattoir. Sexually mature sheep and springbok were selected for the prospective serological study because they are more likely to show serological responses than younger animals. Prior to the serological study, eleven questionnaires were completed on the farms (n=11) that reared sheep and springbok together to gather information about farm management and risk factors for brucellosis. In the serological prevalence study, 332 sheep and 345 springbok sera were collected from the eleven commercial farms and 664 sheep sera were taken from the two communal areas. At the abattoir, 2302 sheep sera were collected from 40 farms in the region using the sample size for determining the absence or presence of disease. All sera were tested for Brucella (B. melitensis, B. abortus) antibodies using the RBT as a screening test and the CFT as a confirmatory test. B. ovis antibodies were tested for in sera from commercial farms only using the CFT test. Results from the retrospective study revealed an apparent sheep brucellosis prevalence of 0.14% (95% CI: 0.1%-0.2%) over the three years and an annual brucellosis prevalence of between 0.05% and 0.19%. At district level, apparent prevalence was between 0% and 0.49%. The prevalence of positive farms was between 0.72% and 1.82%. When apparent prevalence was adjusted for CFT sensitivity and specificity, the prevalence was zero in all cases, suggesting that the prevalence detected in this study may be due to false positive reactions. However, some of the positives serological reactions were from suspected brucellosis clinical cases which were also confirmed by the PCR test. At district level, brucellosis prevalence was shown to be rising in the Karasburg district and decreasing in the Keetmanshoop and Bethanie districts. However, statistical analysis of the data using Fisher’s exact test showed that the differences in brucellosis prevalence between districts was not significant, but that the differences in brucellosis prevalence between the three years was significant. All trace back sera collected in 2011 (using the sample sizes for proving disease freedom) from sheep (n=472) and springbok (n=9) on previously positive farms (n=8) identified by the retrospective study, tested negative for Brucella (B. melitensis, B. abortus, B. ovis) antibodies. The negative results provided strong evidence that brucellosis control measures implemented on the farms following the outbreak were effective and that these farms were now free of brucellosis. Results of questionnaire interviews showed that sheep and springbok were the main species on the farms and that the two species came into close proximity throughout the year especially at watering points in the summer. The interviews also revealed that the study population was naïve because farmers did not vaccinate sheep against brucellosis. All sera collected in the serological study on commercial farms (sheep and springbok), in the two communal areas (sheep) and at the abattoir (culled ewes) tested negative for Brucella antibodies (B. melitensis, B. abortus). The prevalence of B. ovis antibodies in rams on one farm was 10% (3/30). B. ovis antibodies were not detected in springbok. The role of springbok in the epidemiology of sheep brucellosis could not be inferred due to the negative results recorded in both species. Results of the retrospective and prospective serological studies confirmed that apparent brucellosis prevalence in sheep in the Karas Region was low. These results provided evidence that sheep and springbok reared together on the eleven commercial farms were not infected with Brucella. It was surprising that no positive reactors were found in sheep in the communal areas because the intermingling of sheep from different flocks enhances the spread of brucellosis. The absence of positive reactors at the abattoir confirms that the chances of contracting human brucellosis at the abattoir were low and confirms that the forty farms tested were free of Brucella infections. / Dissertation (MMedVet)--University of Pretoria, 2013. / Paraclinical Sciences / unrestricted
3

Feeding ecology of the Kalahari springbok Antidorcas marsupialis in the Kgalagadi Transfrontier Park, South Africa

Stapelberg, Franz Heinrich 24 April 2008 (has links)
Springbok Antidorcas marsupialis ecology was examined on the South African side of the Kgalagadi Transfrontier Park in the Kalahari, with the use of public questionnaires and field forms. Statistically significant differences were found between data that were collected by public respondents and the researcher when using the same questionnaire. Questionnaires are useful for gathering large amounts of data, but should be carefully structured to ensure the quality of the data. Feeding was the most common activity of springbok and the frequency thereof varied during the day and between seasons. Environmental conditions and seasonal changes affected the feeding behaviour of springbok in the southwestern Kalahari. Springbok fed in direct sunlight in the mornings and moved into the shade during the afternoon. More time was spent feeding in the shade during the warmer months than during the colder months, especially under northerly to northeasterly wind directions. Herd sizes were found to increase during the cold-dry season and decreased during the hot-wet season. Springbok and blue wildebeest Connochaetes taurinus taurinus displayed niche separation by competition avoidance. Springbok utilized natural licks. Night-time observations of springbok were made during different seasons and habitats on the South African side of the Kgalagadi Transfrontier Park in 2003. Nocturnal feeding behaviour was described in the context of other similar studies. Feeding times were highlighted, yet the role and importance of nocturnal feeding remains unclear. The nutritional content of some southwestern Kalahari food plant species were determined. The nutrients in the sampled plants showed a wider fluctuation range than plants in other regions. Phosphorus levels in the Kalahari were found to be low in general and calcium levels were higher than in other regions. Browse species contained higher crude protein levels than grass species. The nutritional value of the plants was lowest during the cold-dry season and highest during the hot-dry one. The nutritional status of springbok in the southwestern Kalahari was assessed by using faecal profiling. The faecal nutritional status for springbok populations in different habitats and seasons was examined. Faecal nutrient levels confirmed springbok as mixed feeders with a diet composition that was between that of true browsers and grazers. Faecal concentrations of phosphorus and nitrogen were similar to that of springbok in other areas, but phosphorus intake was shown to be low, particularly during the cold-dry season. Phosphorus appears to be a limiting nutrient and may cause nutritional stress in springbok in the southwestern Kalahari during dry periods. / Dissertation (MSc (Botany))--University of Pretoria, 2007. / Plant Science / unrestricted
4

Studies on the ecology of Carybdea marsupialis (Cubozoa) and jellyfish sting risk management / Estudios sobre la ecología de Carybdea marsupialis (Cubozoa) y gestión del riesgo asociado a picaduras de medusas

Bordehore, Cesar 14 October 2014 (has links)
Programa LIFE Comisión Europea (LIFE NAT 080064 CUBOMED; Ministerio de Agricultura, Alimentación y Medio Ambiente; Fundación Biodiversidad; Dirección General del Agua, Generalitat Valenciana; Fundació Baleària; El Portet de Denia.
5

Uso do espaço por Gracilinanus agilis (Didelphimorphia) e Wiedomys pyrrhorhinus (Rodentia) em área de caatinga no alto sertão sergipano

Cruz, Arthur Oliveira da 24 February 2016 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Studies on communities of small mammals (rodents and marsupials) show different patterns on both selection and use of space in relation to diet, age, and seasonality, among others. To evaluate these standards, spool-and-line technique can provide information about the movement, vertical stratification and the use of shelters and nests by animals. The aim of this study was to evaluate the usage area and selection of microhabitat by Gracilinanus agilis (Didelphimorphia) and Wiedomys pyrrhorhinus (Rodentia) in Monumento Natural Grota do Angico (MNGA), between the cities of Canindé de São Francisco and Poço Redondo, both in Sergipe state. The study was conducted by using Sherman traps to capture the animals, and spool-and-line technique to characterize the movement of these animals in two areas of shrub caatinga vegetation of MNGA, between December/2014 and September/2015. For each individual, data were obtained on the daily home range (AUD), tortuosity of the movement (TORT), index of vertical use (VU) and ground use (%SOLO). The sample for microhabitat selection and availability was performed with ground and canopy cover data and vertical foliar obstruction only to dry period. We evaluated 44 routes (27 G. agilis and 17 W. pyrrhorhinus) representing 2451.42 m of traced line. No differences were found in the movement variables between the dry and rainy seasons for both species (p> 0.0919). Males and females of G. agilis and W. pyrrhorhinus also did not show difference for these variables (p> 0.0643). Comparing the two species, the only difference was on the vertical use (p = 0.0050). Only W. pyrrhorhinus females showed microhabitat selection during daily movement (p <0.0001). Regarding the daily home range (AUD), G. agilis presented, in general, a larger area than W. pyrrhorhinus. Low values of tortuosity (TORT) could be associated with the low population density of these species in the area. The difference in the vertical use (VU) was expected since G. agilis is reported as a scansorial species while W. pyrrhorhinus is preferably arboreal. In general, the absence of habitat selection by sampled environmental variables suggests that G. agilis and W. pyrrhorhinus may be performing this selection on the mesohabitat scale. / Estudos sobre comunidades de pequenos mamíferos (roedores e marsupiais) demonstram diferentes padrões na utilização e seleção do espaço em relação à dieta, idade e sazonalidade, entre outros. Para avaliar estes padrões, a utilização de carretéis de rastreamento pode fornecer informações sobre a movimentação, estratificação vertical e o uso de abrigos e ninhos pelos animais. O presente trabalho teve por objetivo avaliar a área de uso e seleção de microhabitat por Gracilinanus agilis (Didelphimorphia) e Wiedomys pyrrhorhinus (Rodentia) no Monumento Natural Grota do Angico (MNGA), entre os municípios de Canindé de São Francisco e Poço Redondo em Sergipe. O estudo foi conduzido através da utilização de armadilhas Sherman, para a captura dos indivíduos, e de carretéis de rastreamento para a caracterização do movimento desses animais em duas áreas de caatinga arbustiva arbórea do MNGA entre dezembro/2014 e setembro/2015. Foram obtidos dados sobre a área de uso diário (AUD), tortuosidade do movimento (TORT), uso do estrato vertical (VU) e uso do solo (%SOLO) para cada indivíduo. A amostragem da seleção e disponibilidade de microhabitat foi realizada com dados de cobertura do solo e de copa e obstrução foliar vertical apenas para a seca. Foram avaliados 44 trajetos (27 de G. agilis e 17 de W. pyrrhorhinus), totalizando 2.451,42 m de linha rastreada. Não foram encontradas diferenças nas variáveis de movimento entre as estações seca e chuvosa para as duas espécies (p>0,0919). Machos e fêmeas de G. agilis e de W. pyrrhorhinus também não apresentaram diferenciação nessas variáveis (p>0,0643). Comparando-se as duas espécies, houve diferença apenas no uso do estrato vertical (p=0,0050). Apenas as fêmeas de W. pyrrhorhinus evidenciaram selecionar o microhabitat durante o movimento diário (p<0,0001). Em relação ao tamanho da área de uso (AUD), G. agilis apresentou, no geral, uma área maior que W. pyrrhorhinus. Baixos valores de tortuosidade (TORT) encontrados podem ser associados à baixa densidade populacional dessas espécies na área. A diferença na utilização do estrato vertical (VU) era esperada, uma vez que G. agilis é reportado como uma espécie escansorial enquanto W. pyrrhorhinus é preferencialmente arborícola. A ausência, no geral, de seleção do habitat pelas variáveis ambientais amostradas sugere que G. agilis e W. pyrrhorhinus podem estar realizando essa seleção na escala de mesohabitat.

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