No description available.

Almost 50 years of thermophotovoltaic (TPV) research from various sectors has resulted in a variety of potential applications and TPV technology options. In this work the potential of commercial TPV applications is assessed with specific reference to the UK. The assessment considers competing technologies for electricity generation, namely solar photovoltaics, external and internal heat engine generators, electro¬chemical cells and direct heat-to-electricity conversion devices. Electricity generation by TPV conversion from waste heat of industrial high-temperature processes is identified as one of the most suitable TPV applications. This market is examined in more detail using three specific high-temperature processes from the iron and steel and the glass sectors. Results are extrapolated to the entire UK high-temperature industry and include potential energy and CO2 savings. This work gathers knowledge from TPV and other literature sources and evaluates the technological options for the heat source, the radiator and the PV cell for a TPV system. The optical control in terms of the angular, spatial and in particular spectral radiation distributions in cavities is identified as a specific factor for TPV conversion and critical for a system design. The impact of simultaneous radiation suppression above and below the PV cell bandgap on an ultimate efficiency level is examined. This research focuses on fused silica (SiO2) in TPV cavities and examines the aspects of radiation guidance by total internal reflection and spectral control using coupled radiative and conductive heat transfer. Finite volume modelling and experimental work have examined the radiator-glass-air-PV cell arrangement up to a SiO2 thickness of 20 cm. Both show that the efficiency improves for an increased SiO2 thickness. Finally, the novel concept of a TPV cavity consisting of a solid dielectric medium is assessed.

Albian (late Early Cretaceous) pollen and spores were used to reconstruct the floral history of Allison Guyot in the Albian period, to better understand pollen and spore distributions on mid-oceanic islands, to investigate whether Allison Guyot supported land plants in the Albian, and to test previous hypotheses about the development of the guyot. Albian spores found in Allison Guyot sediments from ODP Leg 143 Site 865 include: Laevigatosporites ovatus, Cyathidites minor, Cicatricosisporites sp., Baculatisporites comaumensis, Ceratosporites equalis, Gleicheniidites senonicus, Leptolepidites verrucatus, Retitriletes circolumenus, Lycopodiacidites dettmannae, Osmundacidites wellmanii, Cicatricosisporites hughesii, Impardecispora excavate, and others. Albian pollen from these samples include Callialasporites dampieri, Ephedra, and others occur in Albian samples. The high abundance of terrestrial palynomorphs in these samples suggests that Allison Guyot was exposed in the Albian and supported land plants. The high frequency of spores (more than 90 percent) reflects a flora dominated by ferns.

This thesis concerns the predator-prey interactions of three raptor species in a Swedish arctic community: the gyrfalcon (Falco rusticolus), the rough-legged buzzard (Buteo lagopus) and the golden eagle (Aquila chrysaetos). The gyrfalcon behaved like a highly specialised ptarmigan (Lagopus spp.) predator. Gyrfalcon’s functional response to ptarmigan was close to density independent, and ptarmigan remained the dominating prey even in areas with the lowest ptarmigan density. The gyrfalcon did not respond functionally to microtine rodents (i.e. lemmings and voles) and it was clear that the gyrfalcon did not use microtines as an alternative prey category to ptarmigan. As the gyrfalcons did not switch to any alternative prey when ptarmigan was scarce, their reproductive success seemed to be directly dependent on the amount of ptarmigan available in the breeding territories. Of the two ptarmigan species in the study area, rock ptarmigan (L. mutus) dominated gyrfalcon’s diet. Locally, the proportion of rock ptarmigan in gyrfalcons’ diets showed a positive relationship to the expected availability of rock ptarmigan in the breeding territories, indicating a density dependent utilisation. The rough-legged buzzard behaved like a highly specialised microtine rodent predator and Norwegian lemming (Lemmus lemmus) was its preferred microtine species. The buzzards showed a type 2 functional response to lemmings. Surprisingly though, they also had a type 3 functional response to grey-sided voles (Clethrionomus rufocanus). We present an optimal diet model where a central place forager, during good food conditions, benefits from partial prey preference, which renders separate functional responses to each prey category. We discuss how the double functional responses of the buzzard affect the population dynamics of sympatric vole species, on both temporal and spatial scales. The golden eagle behaved like a generalist predator, and it preyed on all major prey categories in the study area: microtines, ptarmigan, mountain hare, (Lepus timidus) and reindeer (Rangifer tarandus). It seemed to respond functionally to microtine rodent fluctuations with an increased consumption of lemmings during a peak year in the microtine rodent cycle. The golden eagle showed a numerical response to its main prey, the ptarmigan. Ptarmigan, microtine rodents and hares seemed to have synchronized population fluctuations in the study area. Such synchronized population fluctuations are believed to be generated by predation. Although the three raptors are the main predators of their community, their predation patterns fail to explain the observed prey population dynamics in the study area.

Genom sin aktivitet med dammbygge och trädfällning skapar bävern produktiva våtmarker med hög diversitet. Man har funnit att vid bäverns dammkonstruktion var artantalet närmare dubbelt så stort jämfört med i dammen och i det rinnande vattnet i bäcken. Ibland väljer bävern att inte dämma upp vattendragen, utan bygger en hydda längs med strandkanten, något som också kan gynna många arter (Törnblom & Henrikson 2011). Syftet med detta arbete är att undersöka hur själva bäverhyddan, byggd intill strandkanten, påverkar förekomsten av vattenlevande evertebrater. Provtagning på vattenlevande evertebrater har gjorts intill bäverhyddor byggda intill strandkanten, samt uppströms och nedströms varje bäverhydda. Statistiska uträkningar har sedan gjort på insamlad data för att se om det råder någon skillnad i antal individer, antal organismgrupper och diversitetsindex mellan bäverhyddan, uppströms och nedströms. Resultatet visar att det fanns en skillnad i antalet individer mellan hyddan, uppströms och nedströms. Det rådde ingen skillnad i antalet olika organismgrupper eller i diversitetsindex. Vattentemperaturens roll och skyddet som ansamlingen av grenar bidrar med är två aspekter som diskuteras som bidragande faktorer till det förhöjda individantalet vid bäverhyddan. Skillnaden i artsammansättning och artantal mellan bäverdammar och bäverhyddor byggda intill strandkanten är något annat som också diskuteras. / The activity of beavers creates productive wetlands with high biodiversity. A previous study found that dam constructions of beavers contribute to a higher number of aquatic invertebrate species compared to upstream and downstream sites. In some cases beavers build their hut along the shore without damming up the water flow (Törnblom & Henrikson 2011). This report is intended to determine how the beaver hut affects the abundance of water living invertebrates.Sampling at the beaver hut, upstream and downstream, of water living invertebrates was performed. To determine differences in individual number, species number and diversity index between the sites statistical calculation was performed. The results show a difference in individual numbers between beaver huts and downstream and upstream sites and the individual number was higher at the beaver hut than the two other sites. No difference in number of species or diversity index was found. The higher temperature of the water and more nutrition is two aspects that are discussed as contributing factor to the higher number of individuals near the hut. The difference in species and species number between a beaver dam and a beaver hut build long side the shore is also discussed.

Arthropod parasites and micropredators, such as ticks and mosquitoes, influence terrestrial ecosystems and harm their hosts directly and indirectly by vectoring micro-organisms. Whether micropredators similarly affect marine ecosystems and hosts is not well understood. In coral reef fish communities, the most abundant micropredators are isopods, in particular, gnathiids. Our understanding of how isopods affect fishes has been restricted by a lack of information regarding basic isopod biology including; patterns of abundance, parasite identity, host specificity and host pathology. Also it is unknown if small juvenile fish are parasitised by isopods, and if this affects their survival. Sequentially, the aims of my PhD thesis were to understand the ecology of several lesser known parasites in sufficient detail to perform manipulative experiments that could test the effects of micropredation on small juvenile reef fish. All field studies took place at Lizard Island, Great Barrier Reef My first study aimed to describe temporal and spatial patterns of isopod abundance by measuring emergence rates. Gnathiid isopod juveniles emerge from the benthos into the water column to find hosts or change locations. Although diel patterns have been demonstrated, the relationship between substrate and emergence on coral reefs is not clear. I measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera) in 6 “habitats” at 2 very different sites at Lizard Island. Isopods were collected from the periphery and centres of 3 sizes of reef, and from the substrate between these reefs (sand or rubble). At both sites, the most abundant gnathiid species (Gnathia falcipenis and Gnathia sp C), was exclusive to that site. Although strong diel patterns in emergence were observed, gnathiid abundance could not be predicted by habitat. However, gnathiids were larger and more often fed over reef borders than in the centres of reefs. To explain these patterns, I suggested that first stage larvae had the largest influence on total abundance and were patchily distributed in accordance with adults from which they had recently hatched. As later stage larvae also depend on fish, more successful (fed and older larvae) are found on the edges of reefs where appropriate hosts may be more abundant. Gnathiids were over-dispersed in all habitats investigated, including apparently homogeneous beds of coral rubble and sand. This indicated that gnathiid distribution may be better predicted by very fine scale differences in substrate, or that larvae are simply gregarious, and that abundance may be difficult to predict on the basis of substrate. Without reliable differences in parasite abundance among habitats at Lizard Island, subsequent studies would rely on manipulating parasite abundance via excluding wild parasites in the field (which proved very difficult) or by controlling abundance in laboratory simulations. I then investigated host specificity in the 2 most abundant gnathiid species from the previous study. Discrete species distributions between the two sites suggested that the 2 parasites may have had different diets. Host-specificity data for gnathiid isopods are scarce because the parasitic juvenile stages are difficult to identify and host-parasite contact is often brief. Engorged third stage gnathiids were photographed and permitted to moult into adults to allow identification. I compared mtDNA sequences from their blood meals to host sequences available on GenBank. The host frequency distributions used by each species were significantly different; only four host families were shared. I concluded that G. falcipenis and Gnathia sp C operate as preferential feeders. Importantly, this work showed that G. falcipenis was indeed a natural parasite of several species of damselfish (Pomacentridae) that could be collected as young recruits and used in manipulative experiments. I then used G. falcipenis as a model parasite to investigate the effects of isopods on recently recruited Dischistodus perspicillatus and small juvenile Acanthochromis polyacanthus damselfishes. Working with honours student Ms Rose Penfold, we determined that A. polyacanthus was infected by gnathiids in the wild at sizes as small as 4.2 mm SL. Laboratory infections revealed that larger A. polyacanthus were much better at eating gnathiids, a behaviour which prevented infection, and that smaller fish were more likely to die post-infection. Infection prevalence was > 3 % during the day, but we could not sample fish for nocturnal infection prevalence. A caging experiment suggested that most micropredation on damselfish took place at night. For D. perspicillatus, I found that exposure to 2 parasites each evening for 7 nights after settlement halved the growth of these fish. Lastly, numerous free-swimming cymothoid isopods were found associated with larval fish in light traps. Cymothoids have a multi-morphic life cycle composed of micropredatory stages that eventually become females, which are permanently attached to fishes. Because cymothoid taxonomy is based around female morphology, natatory-stage cymothoids can not be identified. I sequenced mtDNA from natatory and adult female life history stages and matched 4 of 11 natatory cymothoid morphotypes. Molecular data were also used to produce a phylogeny exploring the evolution of different forms of host attachment within the Cymothoidae. This phylogeny suggests that external attachment, formerly thought to be plesiomorphic, is a derived condition and has evolved several times independently. I suggest that attachment to the buccal cavity or gills is a primitive form of attachment. This research has provided information on emergence patterns and hostspecificity which is necessary for the future study of isopod vector biology. It also provides a platform for future taxonomic and phylogenetic studies on cymothoids. I demonstrate that gnathiids infect juvenile coral reef fish and suggest that they may influence survival both directly and indirectly by reducing growth and predisposing infected fish to size-selective mortality. Thus, interactions between isopod micropredators and recruiting fishes may determine the survivorship of individual fish and influence the subsequent community structure.

Development actions such as urban, residential, commercial, industrial and mining contribute significantly to the loss of biodiversity worldwide. As development and subsequent loss and degradation of habitats continue, terrestrial biodiversity offsets, or mitigation schemes are conservation instruments that increasingly are being developed, implemented, and used throughout Australia and abroad. However, the failure of offset policies and practices to incorporate sound ecological principles into their design and implementation has led to ineffective conservation and management of biodiversity through offsetting. The aim of this research was to develop a ‘recommended best practice’ offset framework for environments experiencing development pressure, and to inform planners and decision makers on a sound ecological approach to improve biodiversity outcomes for terrestrial ecosystems through the use of offsetting/mitigation schemes. A content analysis technique was applied to evaluate 26 local, provincial, and national biodiversity offset policies, guidance/discussion papers, and planning documents from five countries. Five ecological and planning criteria were applied to evaluate the offset policies. The results from the policy evaluation found that most offset policies contained vague, ambiguous statements and difficult to apply concepts and these results were consistent with a plethora of existing literature, which had identified that the planning of offsets lacked effective consideration and implementation of landscape-ecological principles, and that the protection of biodiversity through offsetting was not occurring. It is therefore important that national, state, and regional policies provide sufficient detail, with definitive performance criteria, indicators and targets, rather than vague principles which are open to ambiguous interpretation and inconsistency in implementation. The results from this research suggested that offset policies failed to protect biodiversity in that the majority of policies evaluated did not effectively incorporate ecological principles that would result in no-net-loss of biodiversity outcomes. This included a failure to recognise and consider the impact of offsets at a landscape-ecosystem scale in relation to ecosystem functionality and the viability of biotic populations. This research also indicated that a variety of tools (e.g., remote sensing, field surveys, and expert opinion) can be used to ensure effective consideration of landscape, ecological, and planning aspects of offsetting. The results of a case study in the Coomera-Pimpama region of Gold Coast City, Australia found that Gold Coast City Council explicitly considered only two of the five recommended off-setting criteria outlined in this research and as a result the conservation of biodiversity and in particular the habitat of the koala (Phascolarctos cinereus) in this area remained threatened. Key strategies were identified to help improve biodiversity outcomes from offsetting and these included: requirements to assess both impacted and offset sites, minimisation of threats to offset sites, and collaboration with professionals in other agencies, ensure that statements are accompanied by definitions, policies provide sufficient detail with definitive performance criteria, indicators and targets, active engagement with agencies dealing with offsetting procedures, professionals, or researchers, effective commitments to facilitative integration, structural integration and collaboration, and strategic integration.

Arthropod parasites and micropredators, such as ticks and mosquitoes, influence terrestrial ecosystems and harm their hosts directly and indirectly by vectoring micro-organisms. Whether micropredators similarly affect marine ecosystems and hosts is not well understood. In coral reef fish communities, the most abundant micropredators are isopods, in particular, gnathiids. Our understanding of how isopods affect fishes has been restricted by a lack of information regarding basic isopod biology including; patterns of abundance, parasite identity, host specificity and host pathology. Also it is unknown if small juvenile fish are parasitised by isopods, and if this affects their survival. Sequentially, the aims of my PhD thesis were to understand the ecology of several lesser known parasites in sufficient detail to perform manipulative experiments that could test the effects of micropredation on small juvenile reef fish. All field studies took place at Lizard Island, Great Barrier Reef My first study aimed to describe temporal and spatial patterns of isopod abundance by measuring emergence rates. Gnathiid isopod juveniles emerge from the benthos into the water column to find hosts or change locations. Although diel patterns have been demonstrated, the relationship between substrate and emergence on coral reefs is not clear. I measured emergence rates of parasitic isopods (Gnathiidea and Flabellifera) in 6 “habitats” at 2 very different sites at Lizard Island. Isopods were collected from the periphery and centres of 3 sizes of reef, and from the substrate between these reefs (sand or rubble). At both sites, the most abundant gnathiid species (Gnathia falcipenis and Gnathia sp C), was exclusive to that site. Although strong diel patterns in emergence were observed, gnathiid abundance could not be predicted by habitat. However, gnathiids were larger and more often fed over reef borders than in the centres of reefs. To explain these patterns, I suggested that first stage larvae had the largest influence on total abundance and were patchily distributed in accordance with adults from which they had recently hatched. As later stage larvae also depend on fish, more successful (fed and older larvae) are found on the edges of reefs where appropriate hosts may be more abundant. Gnathiids were over-dispersed in all habitats investigated, including apparently homogeneous beds of coral rubble and sand. This indicated that gnathiid distribution may be better predicted by very fine scale differences in substrate, or that larvae are simply gregarious, and that abundance may be difficult to predict on the basis of substrate. Without reliable differences in parasite abundance among habitats at Lizard Island, subsequent studies would rely on manipulating parasite abundance via excluding wild parasites in the field (which proved very difficult) or by controlling abundance in laboratory simulations. I then investigated host specificity in the 2 most abundant gnathiid species from the previous study. Discrete species distributions between the two sites suggested that the 2 parasites may have had different diets. Host-specificity data for gnathiid isopods are scarce because the parasitic juvenile stages are difficult to identify and host-parasite contact is often brief. Engorged third stage gnathiids were photographed and permitted to moult into adults to allow identification. I compared mtDNA sequences from their blood meals to host sequences available on GenBank. The host frequency distributions used by each species were significantly different; only four host families were shared. I concluded that G. falcipenis and Gnathia sp C operate as preferential feeders. Importantly, this work showed that G. falcipenis was indeed a natural parasite of several species of damselfish (Pomacentridae) that could be collected as young recruits and used in manipulative experiments. I then used G. falcipenis as a model parasite to investigate the effects of isopods on recently recruited Dischistodus perspicillatus and small juvenile Acanthochromis polyacanthus damselfishes. Working with honours student Ms Rose Penfold, we determined that A. polyacanthus was infected by gnathiids in the wild at sizes as small as 4.2 mm SL. Laboratory infections revealed that larger A. polyacanthus were much better at eating gnathiids, a behaviour which prevented infection, and that smaller fish were more likely to die post-infection. Infection prevalence was > 3 % during the day, but we could not sample fish for nocturnal infection prevalence. A caging experiment suggested that most micropredation on damselfish took place at night. For D. perspicillatus, I found that exposure to 2 parasites each evening for 7 nights after settlement halved the growth of these fish. Lastly, numerous free-swimming cymothoid isopods were found associated with larval fish in light traps. Cymothoids have a multi-morphic life cycle composed of micropredatory stages that eventually become females, which are permanently attached to fishes. Because cymothoid taxonomy is based around female morphology, natatory-stage cymothoids can not be identified. I sequenced mtDNA from natatory and adult female life history stages and matched 4 of 11 natatory cymothoid morphotypes. Molecular data were also used to produce a phylogeny exploring the evolution of different forms of host attachment within the Cymothoidae. This phylogeny suggests that external attachment, formerly thought to be plesiomorphic, is a derived condition and has evolved several times independently. I suggest that attachment to the buccal cavity or gills is a primitive form of attachment. This research has provided information on emergence patterns and hostspecificity which is necessary for the future study of isopod vector biology. It also provides a platform for future taxonomic and phylogenetic studies on cymothoids. I demonstrate that gnathiids infect juvenile coral reef fish and suggest that they may influence survival both directly and indirectly by reducing growth and predisposing infected fish to size-selective mortality. Thus, interactions between isopod micropredators and recruiting fishes may determine the survivorship of individual fish and influence the subsequent community structure.

Thesis (M.Sc.) - Carleton University, 2002. / Includes bibliographical references (p. 100-104). Also available in electronic format on the Internet.

Thèse (D.R.M.)--Université du Québec à Montréal, 1999. / Bibliogr.: f. 176-197. Document électronique également accessible en format PDF. CaQCU