Tesis sobre el tema "Perth Region"

[Truncated abstract] Mediterranean southwest Australia, a global biodiversity hotspot, has nutrient deficient soils, exacting climatic conditions and is species rich with 7380 native vascular plant species, of which 49% are endemic. The region is expected to experience one of the world's highest degrees of biodiversity loss and change in the coming decades, with introduced species presenting a major threat. Limited knowledge is available on the mechanisms of ecosystem change associated with invasion and fire in this biodiversity hotspot region. Banksia woodland, an iconic complex species-rich natural ecosystem is one of the major vegetation types of the coastal sandplain, extending from 15 to 90 km inland and 400 kms along the west coast. The following hypothesis was tested to explore the ecological impacts of invasion: Is invasion of Banksia woodland by the introduced species Ehrharta calycina and Pelargonium capitatum accompanied by an alteration in ecosystem properties and processes, whereby the degree of change is related to fire frequency and abundance of introduced species? Different vegetation conditions, i.e. Good Condition (GC), Medium Condition (MC), Poor Condition invaded by Ehrharta calycina (PCe) and Poor Condition invaded by Pelargonium capitatum (PCp) were utilized for field assessments. ... In the soil seed bank, species numbers and germinant density decreased significantly for native and seeder (fire sensitive) species between GC sites and invaded sites. Surprisingly 52% of germinants at GC sites were from introduced species, with much of the introduced soil seed bank being persistent. Native species were dominated by perennial shrubs, herbs and sedges, while introduced species were dominated by perennial and annual grasses and herbs. Invasion by introduced species, associated with frequency of fire, altered the ecosystem, thus disadvantaging native species and improving conditions for even greater invasion within the Banksia woodland. Significantly higher soil phosphorus P (total) and P (HCO3) were found at PCe and PCp sites compared to GC sites. Leaf nutrient concentrations of phosphorus were significantly higher, and potassium and copper significantly lower in PCe and PCp sites, with introduced species having significantly greater concentrations than native species (except Manganese). This study demonstrated the key role of phosphorus in the Banksia woodland, in contrast to other research which identified nitrogen as the major nutrient affected by invasion. Higher levels of soil and leaf phosphorus, loss of species diversity and function, changes in fire ecology and canopy cover and a limited native soil seed bank make restoration of a structural and functional Banksia woodland from the soil seed bank alone unlikely. Without management intervention, continuing future fire is likely to result in a transition of vegetation states from GC to MC and MC to PC. The knowledge gained from this study provides a better ecological understanding of the invasive process. This enhanced understanding will enable the development of adaptive management strategies to improve conservation practices within a biodiversity hotspot and reduce the impact of the key threatening process of invasion.

Background Quenda (Isoodon obesulus) and brushtail possums (Trichosurus vulpecula) remain in many areas of Perth, Western Australia, despite urbanisation. This thesis investigated the impacts of urbanisation on the parasitic infections, morphometrics and reproductive fitness of these marsupials. Parasite screening particularly investigated the presence of parasites that quenda and possums may be acquiring from humans and pets in urbanised environments. Methods This cross sectional study targeted free-ranging quenda and brushtail possums in Perth. Trapping was undertaken on 29 bushland sites and 35 urbanised sites. Trapped marsupials were sampled for gastrointestinal and macroscopic ecto- parasites and Toxoplasma gondii antibodies, and morphometrics were measured. Statistical analyses included linear and logistic regression, Kulldorff’s spatial scan statistic and analysis of similarities in parasite communities. Results 287 quenda and 33 brushtail possums were sampled across 55 sites. Parasitic infections were common in Perth quenda, and less so in brushtail possums. Twelve parasite taxa were identified infecting these host species for the first time. In quenda, some differences in parasite prevalences, odds of infection, intensities of infection, and parasite communities, were observed in quenda trapped in urbanised environments compared to bushland. In quenda, Giardia spp. infection was common, and typically the non-zoonotic G. peramelis. Analyses suggest that the primary influence on the distribution of Giardia spp. infection in quenda is population density. Quenda trapped in urbanised environments were heavier on average than quenda trapped in bushland, in the absence of convincing evidence of a difference in skeletal morphometrics. Bushland adult female quenda had increased odds of having an active pouch than those in urbanised environments. Conclusions Quenda and brushtail possums in Perth are not commonly infected with gastrointestinal and macroscopic ecto- parasites of humans and domestic animal origin. Quenda in urbanised environments have a tendency towards obesity. Urbanised environments may negatively impact fecundity of female quenda.

Macrozamia riedlei is a long lived, large seeded member of the cycad family, common to the Jarrah forest and Banksia woodlands within the Perth region of Western Australia. Because of the large size of the seeds (up to 50mm), it is believed that large bodied herbivores are required to act as dispersal agents. Currently, the Emu (Dromaius novaehollandiae) is considered to be the primary dispersal agent for M. riedlei. Due to anthropogenic activities, much of the habitat of M.riedlei is becoming fragmented primarily through agricultural and residential land clearing. This leads to the potential restriction of long distance dispersal of seed, required for healthy gene flow and the ability for range expansion in the face of an uncertain climatic future. The aims of this study were to investigate the current population structure of M. riedlei at three locations within the Perth region and to identify dispersal agents and the distance they can disperse seeds. The sites chosen were Avon Valley, Sawyers Valley and Kings Park; these three sites were chosen since they present a gradient in emu population density, from abundant at Avon Valley to absent for a century at Kings Park. To ascertain how these three populations of M. riedlei were currently structured, all plants in replicate 50x50m plots were recorded at each site and the data used to analyse the demographic and spatial structure of each population. Because of the gradient in emu population density, it was hypothesised that the spatial and demographic structure would differ at each site, due to the availability of emus to disperse the seeds of M. riedlei. The three study sites were shown to be very similar in population structure despite the difference in emu numbers. It was also found that the Australia Raven (Corvis coronoides) was capable of dispersing the seeds of M. riedlei over distances of up to 390m, indicating that ravens are able to act as suitable dispersers of M.riedlei seeds and in the absence of emus maybe considered as a key dispersal agent.

Zanna and Rempel (1988) have proposed that attitudes are a summary evaluation of an attitude object based on three classes of information, namely: cognitive information, affective information and behavioural information. This model has mainly been tested in the social groups and social policies area investigating two classes of information: cognitive and affective, and therefore there is a need for research to test the validity of this model in other areas. The present study applies the model to the area of palliative care in nursing homes. 76 directors of nursing, 76 clinical nurse specialists, and 76 nursing assistants working in nursing homes, completed a questionnaire in which they were asked (a) to make an evaluation of their overall attitude on a 7-point semantic differential scale, (b) to write down their own beliefs and (c) affects in response to the attitude object "palliative care in nursing homes" and then rate these beliefs and affects on a 7-point Likert Scale (d) to answer 18 factual knowledge questions about palliative care, and (e) to supply some demographic information. The results indicated that cognitive and affective information significantly and independently predicted the attitudes of nurses to palliative care in nursing homes.

Rapid development and growth of industrialization has brought immense enrichments in living standards of humans, however, improper planned development also brings along several environmental problems such as pollution of environment and excessive consumption of natural resources. Among all the others, uncontrolled utilization of water poses a severe threat to the coming generations. Past decades have witnessed water shortage in various countries of the world. Although about 80% of the earth’s surface is covered with water, around 97.2% of water is salty making it inappropriate for general usage. Among the rest of the 2.8%, which is present as fresh water on surface, a large proportion of it has been found to be severely polluted. The increasing demand of fresh water both for industrial and domestic usage adds great demand on the available groundwater. Moreover, the severe pollution of fresh water on the surface adds more stress on the available groundwater. In Australia, approximately 20% of water supply is from groundwater and in the case of Western Australia groundwater provides two thirds of its water supply needs. Thus, it is important to manage groundwater sources in Western Australia to achieve the optimum water utilization and maintain the water table and it is also essential to decide on an appropriate water budget. Groundwater flow modelling is an effective tool to get appropriate water distribution and, to examine effects from pumping on water levels and direction of groundwater flow paths, thereby helping in its proper management and utilization. Apart from monitoring the flow and utilization, groundwater flow modeling is also vital to keep the track of pollutant in the groundwater. Increasing surface pollution and landfill sites tend to pollute the groundwater due to leaching.The above mentioned aspects formed the basis of the present research. A groundwater flow model was developed in Visual MODFLOW Premium to study the effect of three different types of soil in and around Perth region. This study also shows the hypothetical contaminated site model for benzene, toluene, ethylbenzene and xylene (BTEX) transport in Perth Superficial unconfined aquifer which includes three major aquifer sediments namely Bassendean Sand, Safety Bay Sand and Tamala Limestone. Among the four different contaminants it was observed that benzene is able to migrate quickly as compared to the other contaminants due to its smaller distribution coefficient.This study also explored the major soil parameters such as effect of sorption, effective porosity and hydraulic conductivity on contaminant plume configuration and contaminants concentration for the three types of aquifer sediments. A critical comparison of the behaviour of the three different types of soils was also conducted.Simulation results of sensitivity analysis have shown that sorption and hydraulic conductivity greatly affected the contaminant plume length and concentration of contaminants with much lesser effect shown by the effective porosity. The simulated results also showed that the movement of contaminant in Tamala Limestone is most rapid by comparing these three types of aquifer sediments together. Thus, it can be said that contaminated sites found in Tamala Limestone needs immediate remediation of contaminants to bring down the contaminants concentration in groundwater.In brief, the thesis explores the current groundwater scenario in and around Perth region. Based on the information a hypothetical scenario simulation has critically analyzed the various parameters affecting the water and contaminant flow for the various soil parameters. The study is considered as a building block for further research on developing a remediation technique for groundwater contaminant treatment.

Rapid development and growth of industrialization has brought immense enrichments in living standards of humans, however, improper planned development also brings along several environmental problems such as pollution of environment and excessive consumption of natural resources. Among all the others, uncontrolled utilization of water poses a severe threat to the coming generations. Past decades have witnessed water shortage in various countries of the world. Although about 80% of the earth’s surface is covered with water, around 97.2% of water is salty making it inappropriate for general usage. Among the rest of the 2.8%, which is present as fresh water on surface, a large proportion of it has been found to be severely polluted. The increasing demand of fresh water both for industrial and domestic usage adds great demand on the available groundwater. Moreover, the severe pollution of fresh water on the surface adds more stress on the available groundwater. In Australia, approximately 20% of water supply is from groundwater and in the case of Western Australia groundwater provides two thirds of its water supply needs. Thus, it is important to manage groundwater sources in Western Australia to achieve the optimum water utilization and maintain the water table and it is also essential to decide on an appropriate water budget. Groundwater flow modelling is an effective tool to get appropriate water distribution and, to examine effects from pumping on water levels and direction of groundwater flow paths, thereby helping in its proper management and utilization. Apart from monitoring the flow and utilization, groundwater flow modeling is also vital to keep the track of pollutant in the groundwater. Increasing surface pollution and landfill sites tend to pollute the groundwater due to leaching.<br>The above mentioned aspects formed the basis of the present research. A groundwater flow model was developed in Visual MODFLOW Premium to study the effect of three different types of soil in and around Perth region. This study also shows the hypothetical contaminated site model for benzene, toluene, ethylbenzene and xylene (BTEX) transport in Perth Superficial unconfined aquifer which includes three major aquifer sediments namely Bassendean Sand, Safety Bay Sand and Tamala Limestone. Among the four different contaminants it was observed that benzene is able to migrate quickly as compared to the other contaminants due to its smaller distribution coefficient.<br>This study also explored the major soil parameters such as effect of sorption, effective porosity and hydraulic conductivity on contaminant plume configuration and contaminants concentration for the three types of aquifer sediments. A critical comparison of the behaviour of the three different types of soils was also conducted.<br>Simulation results of sensitivity analysis have shown that sorption and hydraulic conductivity greatly affected the contaminant plume length and concentration of contaminants with much lesser effect shown by the effective porosity. The simulated results also showed that the movement of contaminant in Tamala Limestone is most rapid by comparing these three types of aquifer sediments together. Thus, it can be said that contaminated sites found in Tamala Limestone needs immediate remediation of contaminants to bring down the contaminants concentration in groundwater.<br>In brief, the thesis explores the current groundwater scenario in and around Perth region. Based on the information a hypothetical scenario simulation has critically analyzed the various parameters affecting the water and contaminant flow for the various soil parameters. The study is considered as a building block for further research on developing a remediation technique for groundwater contaminant treatment.

Based on an ethnographic study of the everyday practices of diasporic Chinese residents of Perth, this project focuses on the relationship between the ecologic environment and diasporic Chinese cultures in contemporary Western Australia. With the acceleration of globalization, studies in diaspora have increasingly absorbed geographic ideas. Research on the relationship between ecology and humankind has thrown new light on discussions of diaspora. However, there are few in-depth studies addressing the construction of diasporic place and space with an engagement of the material world. Considering the relative absence of the natural world as a serious subject in contemporary diaspora studies, the starting point of this project is to explore the interactive relationships between place, space, and diasporic people via their everyday experiences. What is the meaning of nature to Chinese people living in Australia? How do they communicate with the natural world in their daily life and what is the dynamic relationship between the people and the environment? In order to find the answers to these research questions, I adopt sensory ethnography, multispecies ethnography and sensory studies of food as the major approaches. As an insider ethnographer, I have examined diasporic multisensoriality through the ethnographic practices of interviews, observation, filed documentation (notes, photos, sound recordings), film documentation (video documentation of abalone harvesting in chapter 8) and self-reflective composition within a dynamic assemblage of human and nonhuman agentic beings. Sensory studies of food provide a way to understand the dynamic relations between the materials in diets and Chinese people on individual, ethnic and diasporic scales. Along with the theoretical themes of place, space, food, perception, memory and imagination, this research traverses diverse ethnographic disciplines as an academic practice. In this research, I present several typical cases of everyday spatial practices, abalone recreational harvesting, and Chinese vegetable gardening. As an ethnographic study, the project has involved more than twenty specific participants. In the last two years, I have interviewed groups, individuals and families, and joined them in wine tasting, cultural celebrations, abalone harvesting and vegetable gardening. In addition, due to my previous background in documentary filmmaking, I have made an illustrative film on the topic of abalone harvesting. Through the research on the cases, I found that there is an intimate, dialogical and reciprocal connection between the Chinese diaspora in Perth and the local physical environment. With the embodied engagement of the natural surroundings in their daily experiences, Chinese people living in Perth have gradually converted their perceptions of nature, which are also under the influence of traditional cultures. Acting as a space and an agent, the ecological environment has become familiar and domestic in the people’s diasporic experiences. Additionally, daily practices in the material surroundings have also transformed the people’s self-perceptions through their senses, reflections and attitudes toward the natural world. At the same time, the natural environment is impacted upon in myriad ways by the activities of diasporic Chinese.

Exploratory research examined how two governments and a citizen regional water catchment group implemented adaptive management in two Australian environmental management policies. The research question asked how theories of action between government and regional bodies influenced their relationships.The research question was first conceived as solely human, but another metaphysics (actor-network theory), enabled following the intertwining of study objects such as adaptive management, natural resource management, and policy, and a potential rethink of environmental reality.

The subject matter of this study is the consumption of suburban housing in Australian metropolitan regions between the two world wars. Specifically, it examines the distinctiveness of what was owned and occupied by whom in relation to later developments. Despite the period being of considerable significance in the growth of urban residential areas, it has not been well researched and this mainly involves two methodological problems. The first is the dearth of detailed data; the second is the lack of an established theoretical framework to guide investigations. Clearly the two elements are interrelated and therefore this study is as much about the development of a body of relevant information as it is about a conceptual interpretation of the findings. Turning to the first difficulty, the problem is not only the availability of data for the period per se, but also to relate it to the overall development of suburbs. This has entailed a reworking of census data and to that end, growth groups were devised and found to be more sensitive than zones to portray trends within However, metropolitan areas. this still does not overcome the data gap, particularly between 1921 and 1947, and consequently a detailed study has been made of Victoria Park from the rate books and sewerage plans. This covers the period from 1900 to 1955 and thereby provides a wider time frame to assess the distinctiveness of the period between the two world wars. With regard to the second difficulty, many studies appear to seek direct cause and effect linkages which have shaped urban phenomena. In this study, following the ideals of structuration, the view is taken that suburban housing is interconnected with the wider social structure in a mutually responsive relationship. Within this framework, the proposition is that there has been a shift in emphasis from houses as places for the sustenance of labour to locations for the consumption of a widening array of goods and services, including the house itself; and that this emerged strongly between the two world wars. While there are many facets to the study of suburban growth and development, two particular issues are used to direct this research. The first is the nature of occupancy, characters of dwellings and the relationships between them as indicators of changes in the consumption of housing. The second is the role of gender in these developments. The latter is considered to be significant because one of the apparent outcomes of suburbanization in the period was the segregation of males and females; and furthermore, while the suburbs were the domain of women, men appeared to control access to the means of consumption. From an analysis of the data developed at the macro scale of the Greater Perth Metropolitan Region, based on 26 Local Government Areas, and the micro level of Victoria Park using more than 6000 dwellings, the following findings have been made. Firstly, home ownership was a significant, although obscured, element of the suburbs which developed between the two world wars. Secondly, while the depression had a devastating and prolonged impact on home ownership in working class areas such as Victoria Park, in so doing, the proportion of outright to mortgage ownership increased. Thirdly, the period between the wars was part of a longer term trend for homes to have more rooms, often at the expense of verandahs, and fewer inhabitants. Fourthly, despite the fact that established suburbs had a majority of females, men still either owned or were nominated as the principal occupiers of the majority of residences. However, between the wars, not only did the level of female ownership increase significantly, but joint ownership also emerged as a the major form of occupancy. Fifthly, during the same period, there was a marginal propensity for sole males to own slightly larger, more expensive, brick homes while sole females owned slightly smaller, cheaper, weather-board residences. However, there is no clear distinction in terms of either age of dwellings or distance to the closest tram stop or railway station. Finally, although Perth has been characterised as a brick city, initial housing in the new suburbs, particularly in the period which encompassed the two world wars, were usually constructed of cheaper, more easily transported and constructed materials. The emphasis on brick homes was usually a feature of later consolidation phases of urban development. From these findings it is concluded that housing, as both a major item of consumption, and as the venue for increasing levels of household consumption, was well established in the suburbs which developed between the two world wars. As such, it is suggested that residential areas need to be seriously viewed as places of consumption and this consideration tied into any endeavour to plan future developments.

Barramundi (Lates calcarifer) is a centropomid teleost with a wide distribution across the Indo Pacific. In Australia, barramundi are native to the tropical zone from Exmouth Gulf in Western Australia, across the northern part of the continent, to the Mary River in Queensland. Barramundi are protandrous hermaphrodites, and are euryhaline, with a catadromous life history. Barramundi are a valuable Australian resource, with important commercial and recreational fisheries and aquaculture production to the value of $11 million dollars per year. Recent declines in the availability of the fish in some rivers has led to an interest in the possibility of restocking rivers with barramundi from other areas. Determining the genetic structure of barramundi populations in Australia is important for understanding biogeographic history, and appropriate management practices for both aquaculture and recreational and commercial fishing. Previous studies have concentrated on the east coast of Australia, and have largely ignored the western populations. In this study, I obtained DNA data from barramundi populations across the Australian range of the species, as well as populations from Papua New Guinea and Indonesia. The aims of this study were to use the genetic data to determine: 1. if populations in Western Australia show genetic differences between geographic regions 2. if these populations show an ancestral split from populations in the east of Australia and 3. the ancestral origins of Australian barramundi. Previous studies of DNA data from barramundi have discovered an east/west split occurring at the Torres Strait that was assumed to be caused by the closing of the strait during lowered sea levels. However, these studies suffered from a bias in sampling area, concentrating either on the eastern half of the range of barramundi, or on the western tip of the range. Data from these studies were combined and reanalyzed. Two major clades were discovered, with considerable biogeographic structuring, but their geographic locations did not coincide with the reported vicariance event at the Torres Strait. Instead,historical divisions among freshwater drainage systems appeared to have driven the evolutionary history of barramundi in Australia. In order to investigate these historical divisions further, a 290 bp section of the mitochondrial DNA control region was sequenced in 284 barramundi from seven populations across the Australian geographic range of the species and from one population in Papua New Guinea and one population in Indonesia. Analyses of molecular variance within and among populations showed significant geographic structuring, based on biogeographical provinces and drainage divisions. Nested clade analyses indicated that these geographical associations were the result of restricted gene flow, range expansion, and past fragmentation events. I hypothesise that the Ord River area in the west of the continent was the ancestral source population for the rest of the species' range across Australia, with Indonesia being the most likely origin of this source. Populations of barramundi from the Pilbara region are genetically distinct and geographically isolated, with strong evidence of an ancestral divide along geographical barriers to dispersal. There is a strong association between Papua New Guinea and Australia, although further investigations using the cytochrome b region of mitochondrial DNA indicated a more ancestral divide between the two than is currently evident, which could reflect an ancient geographical divide between the two, or could be evidence of a secondary migration route to Australia. For a more detailed study of evolutionary processes acting on populations of barramundi in Western Australia, allelic diversity was examined at five microsatellite loci. All loci were polymorphic and genotypic frequencies conformed to Hardy-Weinberg expectations, with no significant linkage between loci evident in any population. Measures of within population diversity were significantly related to latitude, suggesting southerly migration from a northern source population. The Ord River was the most genetically diverse population, and the most likely ancestral migration source to the area, with diversity decreasing down the west coast. Although there were significant differences among populations, the nuclear microsatellite data do not indicate the same degree of genetic structuring as is evident in the mitochondrial data. This may be a consequence of rapid evolutionary change at microsatellite loci, with past separations or population differences masked by recombination and back mutation of the microsatellite alleles. However, the nature of nuclear and mitochondrial inheritance may also indicate life history differences between the sexes, where significant genetic contribution to gene flow by males and limited female gene flow may lead to preservation of maternally inherited population substructure. The principal findings from this study are: * There is no genetic evidence for an east/west division of barramundi populations in Australia, as suggested by previous research. * Despite barramundi's catadromous life history, and ability to disperse through marine waters, the present genetic structure indicates a division principally among river drainages. From a population genetic viewpoint, the species can be regarded as freshwater, rather than marine. * The most likely origin of barramundi in Australia is the Ord River region, with Indonesia as the route of migration. * Differences in the population structure demonstrated by nuclear and mitochondrial data indicate possible life history differences between the sexes. * Barramundi populations in different biogeographical provinces may have been substantially isolated over a long period of time, and may therefore represent independently evolving populations. This has important implications for fishery management and translocation issues for restocking rivers.

Barramundi (Lates calcarifer) is a centropomid teleost with a wide distribution across the Indo Pacific. In Australia, barramundi are native to the tropical zone from Exmouth Gulf in Western Australia, across the northern part of the continent, to the Mary River in Queensland. Barramundi are protandrous hermaphrodites, and are euryhaline, with a catadromous life history. Barramundi are a valuable Australian resource, with important commercial and recreational fisheries and aquaculture production to the value of $11 million dollars per year. Recent declines in the availability of the fish in some rivers has led to an interest in the possibility of restocking rivers with barramundi from other areas. Determining the genetic structure of barramundi populations in Australia is important for understanding biogeographic history, and appropriate management practices for both aquaculture and recreational and commercial fishing. Previous studies have concentrated on the east coast of Australia, and have largely ignored the western populations. In this study, I obtained DNA data from barramundi populations across the Australian range of the species, as well as populations from Papua New Guinea and Indonesia. The aims of this study were to use the genetic data to determine: 1. if populations in Western Australia show genetic differences between geographic regions 2. if these populations show an ancestral split from populations in the east of Australia and 3. the ancestral origins of Australian barramundi. Previous studies of DNA data from barramundi have discovered an east/west split occurring at the Torres Strait that was assumed to be caused by the closing of the strait during lowered sea levels. However, these studies suffered from a bias in sampling area, concentrating either on the eastern half of the range of barramundi, or on the western tip of the range. Data from these studies were combined and reanalyzed. Two major clades were discovered, with considerable biogeographic structuring, but their geographic locations did not coincide with the reported vicariance event at the Torres Strait. Instead,historical divisions among freshwater drainage systems appeared to have driven the evolutionary history of barramundi in Australia. In order to investigate these historical divisions further, a 290 bp section of the mitochondrial DNA control region was sequenced in 284 barramundi from seven populations across the Australian geographic range of the species and from one population in Papua New Guinea and one population in Indonesia. Analyses of molecular variance within and among populations showed significant geographic structuring, based on biogeographical provinces and drainage divisions. Nested clade analyses indicated that these geographical associations were the result of restricted gene flow, range expansion, and past fragmentation events. I hypothesise that the Ord River area in the west of the continent was the ancestral source population for the rest of the species' range across Australia, with Indonesia being the most likely origin of this source. Populations of barramundi from the Pilbara region are genetically distinct and geographically isolated, with strong evidence of an ancestral divide along geographical barriers to dispersal. There is a strong association between Papua New Guinea and Australia, although further investigations using the cytochrome b region of mitochondrial DNA indicated a more ancestral divide between the two than is currently evident, which could reflect an ancient geographical divide between the two, or could be evidence of a secondary migration route to Australia. For a more detailed study of evolutionary processes acting on populations of barramundi in Western Australia, allelic diversity was examined at five microsatellite loci. All loci were polymorphic and genotypic frequencies conformed to Hardy-Weinberg expectations, with no significant linkage between loci evident in any population. Measures of within population diversity were significantly related to latitude, suggesting southerly migration from a northern source population. The Ord River was the most genetically diverse population, and the most likely ancestral migration source to the area, with diversity decreasing down the west coast. Although there were significant differences among populations, the nuclear microsatellite data do not indicate the same degree of genetic structuring as is evident in the mitochondrial data. This may be a consequence of rapid evolutionary change at microsatellite loci, with past separations or population differences masked by recombination and back mutation of the microsatellite alleles. However, the nature of nuclear and mitochondrial inheritance may also indicate life history differences between the sexes, where significant genetic contribution to gene flow by males and limited female gene flow may lead to preservation of maternally inherited population substructure. The principal findings from this study are: * There is no genetic evidence for an east/west division of barramundi populations in Australia, as suggested by previous research. * Despite barramundi's catadromous life history, and ability to disperse through marine waters, the present genetic structure indicates a division principally among river drainages. From a population genetic viewpoint, the species can be regarded as freshwater, rather than marine. * The most likely origin of barramundi in Australia is the Ord River region, with Indonesia as the route of migration. * Differences in the population structure demonstrated by nuclear and mitochondrial data indicate possible life history differences between the sexes. * Barramundi populations in different biogeographical provinces may have been substantially isolated over a long period of time, and may therefore represent independently evolving populations. This has important implications for fishery management and translocation issues for restocking rivers.

Metal-contamination of lakes simplifies food webs and reduces the efficiency of energy transfer to top trophic organisms, such as yellow perch (Perca flavescens). Benthic invertebrate community composition and yellow perch diet, growth and activity levels from lakes along a metal-contamination gradient were used to assess the importance of a naturally diverse prey base for maintaining energy transfer to growing fish, and how this is disrupted by metal-contamination. As perch grow larger, they shift their diet to larger prey; otherwise, the activity costs of foraging for many, small prey, instead of a few large prey, become too high and the fish stop growing. Metal contaminated lakes have less diverse zoobenthic communities, particularly the lack of large bodied invertebrate taxa, forcing perch to rely on smaller benthic prey. Perch from metal-contaminated lakes display slow growth and poor condition during benthivory. Estimates of fish activity, using the activity of the glycolytic enzyme Lactate dehydrogenase in perch white muscle tissue as a proxy, suggest that diet shifts to larger prey lower activity costs and may explain how diet shifts maintain growth efficiency as perch grow larger. Perch from metal-contaminated lakes cannot benefit from the energetic advantages of switching to larger prey and thus exhibit poor growth.

La production annuelle francaise de viande qui est d'environ 5. 4 millions de tonnes doit obligatoirement etre refrigeree avant toute operation de decoupe et tout transport des carcasses. L'objectif de ce travail etait de calculer les cinetiques de temperature et de perte de poids des carcasses. Un modele reposant sur les solutions analytiques relatives au cylindre infini a ete adapte pour tenir compte de la variation dans le temps des conditions de refrigeration telles qu'elles existent dans les appareils industriels. Il permet de calculer rapidement et simplement les cinetiques sur un micro-ordinateur (environ 30 secondes). Le modele a d'abord ete valide sans ajustement, en regimes constant et variable, par des experiences realisees sur des echantillons cylindriques en platre mouille. La demarche permettant d'utiliser ce modele pour simuler le refroidissement d'un objet de forme complexe, par ajustement d'un facteur de forme et d'une surface d'echange equivalente, a ete testee sur un moulage d'un quartier arriere de porc. Elle a ensuite ete appliquee avec succes a deux produits choisis en fonction de leur taille: (1) des carcasses de lapin, 55 essais ont ete realises en regime constant (0. 3 m/s < v#a < 2. 0 m/s, -3c < t#a < 10c et 70% < hr < 90%) et 9 en regime variable (0. 5 m/s < v#a < 2 m/s, -5c < t#a < 5c), (2) des quartiers arriere de porc, 20 essais ont ete realises en regime constant (0. 5 m/s < v#a < 2. 0 m/s, 0c < t#a < 8c et 70% < hr < 90%) et 10 en regime variable (0. 6 m/s < v#a < 2. 0 m/s, -8c < t#a < 0c). Le bon accord observe entre les calculs et les mesures dans tous les cas incite a proposer cet outil de simulation aux professionnels pour comparer rapidement et facilement l'effet de diverses solutions techniques sur les temps de refrigeration et les pertes de poids

Fatty acids (FAs) are used as trophic markers in aquatic food web studies, but few studies have quantified individual variability in FAs profiles over several sites in a range of conditions. I investigated whether FAs profiles of yellow perch (YP), Perca flavescens, vary with body size and between lakes with and without largemouth (Micropterus salmoides), and smallmouth bass (Micropterus dolomieu), the most common and abundant piscivores in lakes of the region. I analyzed the FAs of YP as well as zooplankton, benthic invertebrates, and prey fish collected from eight lakes where bass were either present or absent in the Outaouais region over the summer of 2016. I compared the growth rate of YP between the lakes and the YP in lakes without bass exhibited a slower growth rate. I also compared the FA signatures of YP using redundancy analysis (RDA). 23 FAs could be identified and quantified. FAs profiles were dominated by palmitic- (16:0), oleic- (18:1), stearic- (18:0), and palmitoleic acid (16:1). The RDA analysis based on FAs profiles of YP revealed variation along two main gradients (the presence of bass and the date of capture). The first two eigenvectors accounted for 42.1% of the variation (RDA1=27.6% and 2=14.6%). Arachidonic (20:4) and docosatrienoic (22:3) were the most correlated FAs with RDA1. Due to the sampling period, it was impossible to determine if the observed effects were due to the date of capture, the presence of bass, or a change in metabolism, but the last two were deemed as the most plausible explanations. It was concluded that the utility of FA signatures to quantify diet in natural environments is limited and that FAs might be more successful as markers in primary consumers and other lower trophic levels. It is recommended that a combination of FAs, stable isotopes, and modelling should be used in the future.

Etude des champs transitoires rayonnes par transducteurs de formes variées en tenant compte aussi bien des conditions aux limites que de l'atténuation du milieu de propagation. Généralisation de l'approche intégrale de Kirchhoff à la propagation en milieu atténuant et détermination des différentes fonctions de green.

L'etude experimentale porte sur plusieurs systemes : 4 types de solides (3 supports de catalyseur et des billes de verres, 2 liquides (eau ou cyclohexane) et 2 gaz (air ou azote) ainsi que 2 tailles de colonne (5 ou 15 cm). On suit l'influence de ces parametres sur le regime d'ecoulement, la retenue liquide et gazeuse et sur les pertes de charges

De nouvelles mesures de la perte de charge diphasique et du taux de vide local ont ete effectuees pour ecoulement diphasique adiabatique ou en condensation dans un canal de section rectangulaire (lisse, arrangement d'obstacles en ligne ou en quinconce). Des correlations du taux de vide et du coefficient diphasique de frottement sont developpees a partir des donnees. Des comparaisons entre la chute de pression et l'intensification du transfert thermique sont presentees. Les points experimentaux sont determines dans des conditions industrielles de fonctionnement. Des cartes experimentales de repartition de taux de vide donnent des informations sur la distribution d'un ecoulement diphasique dans un arrangement d'obstacles. Nous demontrons que l'etude de la fonction densite de probabilite des fluctuations du taux de vide peut etre utilisee comme un indicateur objectif pour determiner le type de l'ecoulement diphasique en presence: ecoulement a bulles, a bouchons ou annulaire

Le présent travail concerne une étude expérimentale de l'hydrodynamique et du transfert de matière liquide/solide à la paroi d'un réacteur à lit fixe par deux approches complémentaires: l'approche globale à l'échelle macroscopique et l'approche locale à l'échelle microscopique. La méthode polarographique, fondée sur la mesure du courant limite de diffusion d'une substance électroactive présente en faible quantité au sein de la solution liquide, a été utilisée. Deux configurations d'écoulement ont été considérées: l'écoulement monophasique du liquide et l'écoulement gaz/liquide à co-courant vers le bas. L’influence du nombre de Schmidt (nature du liquide) a été analysée dans les différents régimes hydrodynamiques proprés à chaque configuration d'écoulement. Après une description détaillée du montage expérimental et des méthodes de mesures des paramètres hydrodynamiques et du transfert de matière, un intérêt particulier a été porté à la mise au point du système de mesure, en présence et en absence de gaz, afin d'assurer une bonne qualité des mesures. Dans chaque configuration, les régimes d'écoulement, les pertes de charge et le transfert de matière ont été déterminés. Un tube en nickel platine (macroélectrode) a été utilisé pour mesurer le transfert global de matière, alors que des microélectrodes en platine, sur paroi conductrice, ont permis de mesurer le transfert local. Les mêmes microélectrodes, mais en paroi inerte, ont permis d'analyser l'hydrodynamique à l'échelle locale. En plus des techniques du traitement classique du signal, l'approche fractale a été utilisée pour caractériser les performances des réacteurs à lit fixe à travers l'état du mélangeage de la phase liquide. Tous les résultats expérimentaux ont été systématiquement confrontés aux prédictions de la littérature. En transfert de matière, des corrélations propres de nos mesures sont proposées avec une analyse statistique des paramètres utilisés pour leur établissement. Des comparaisons entre les transferts de matière et de chaleur ont été effectuées afin de mettre en évidence des analogies entre ces deux phénomènes de transport

La banalisation de l'emploi d'onduleras à Modulation de Largeur d'Impulsion pour l'alimentation des machines asynchrones rend indispensable l'étude des pertes magnétiques supplémentaires qu'ils engendrent. L'influence des paramètres principaux de la MLI, fréquence de hachage et paramètre de modulation est étudiée, grâce à un banc de mesure de type cadre Epstein spécialement adapté. L'emploi d'un moteur instrumenté de 4 kW permet d'observer les formes d'ondes réellement présentes dans les différentes parties du circuit magnétique et de montrer que la déformation du signal MLI entraîne une forte augmentation des pertes magnétiques. Le calcul des pertes totales du moteur à partir des formes d'ondes révèle qu'il existe un écart important avec les pertes fer mesurées par la méthode standardisée, car celle-ci ne permet pas une décomposition détaillée des pertes. Une méthode plus précise est donc proposée. Cependant, l'amélioration du calcul des pertes fer passe aussi par une meilleure prise en compte de la géométrie et des phénomènes locaux, que seule une simulation par éléments finis permet d'approcher. Une méthode originale d'estimation des pertes basée sur une caractérisation préalable du matériau dans un large domaine d'inductions et de fréquences est donc présentée. Cette méthode permet de retrouver les cycles d'hystérésis dynamiques dans des conditions d'excitation quelconques. Elle a été associée au logiciel de calcul par éléments finis FLUX2D et appliquée avec succès au calcul des pertes magnétiques dans le stator et le rotor d'une machine asynchrone