No description available.

Scleractinian corals increasingly are studied as geochemical archives of modern- and palaeoclimate, but microsampling for geochemical data is complicated by: 1) the microstructural complexity and spatial variability in skeletal growth in different coral genera; and 2) the rapidity and scale of diagenetic alteration that occurs in living coralla. Geochemical sampling techniques now have spatial resolution into the sub-micrometer to tens of micrometers range, and it is hoped that the spatial resolution can be translated to temporal resolution. This study investigated the effects on geochemical analyses imposed by microstructure and diagenesis in different live-collected coral genera representing somewhat different depositional environments. Suites of samples of four reef-building genera (Acropora, Pocillopora, Goniastrea and Porites) were collected from three adjacent environments in intertidal and subtidal positions near the reef edge at Heron Reef, Great Barrier Reef and studied by means of optical and scanning electron microscopy, combined with vibrational and energy dispersive spectroscopy. The first section of this study compares and documents the microstructure of the four coral genera. Each genus was found to have very different three-dimensional arrangements of microstructural elements, and a new general growth model was proposed for Acropora, to take into account differences in the timing of precipitation of trabeculae and thickening deposits. The results highlight the complexity and spatial variability of skeletal growth in different coral genera. Because microstructural patterns vary in different genera, direct observation of microstructural elements and growth lines are necessary to allow geochemical microsamples to be placed into series that represent temporal sequences with known degrees of time averaging. Coral growth rates (i.e., rates of extension) are discussed to determine the range of temporal relationships that exist between closely spaced skeletal microstructural elements. Such data are necessary in order for coral skeletogenesis to be understood and are critical for constraining microsampling strategies aimed at developing true time series geochemical data at very fine spatial and temporal scales. The second part of the study focused on early diagenetic alteration of the corals, which is an equally important concern for geochemical analysis. Early marine diagenesis was documented in the same live-collected samples of the four common reef-building coral genera. Samples show extensive early marine diagenesis where parts of the coralla less than three years old contain abundant macro- and microborings (sponges, algae, cyanobacteria and fungi) and significant amounts of aragonite, high-Mg calcite, low-Mg calcite and brucite [Mg(OH)2] cements. Many of the cements are associated with microendoliths and endobionts that inhabit recently abandoned parts of the skeleton. The cements are problematic for palaeoclimate reconstruction because geochemical proxies used for paleoclimate studies are meant to reflect ambient seawater chemistry and conditions, but the occurrence of brucite and low-Mg calcite demonstrates how far fluid chemistry in microenvironments within the corals has evolved from ambient seawater. Some Porites lobata specimens have had as much as 60% of the most recently deposited skeletal aragonite (i.e., the part of the skeleton that projects into the layer of living polyps) bored and replaced by low-Mg calcite cement. The low-Mg calcite cement has significantly different trace element ratios (Sr/Ca(mmol/mol) = 6.3 ± 1.4; Mg/Ca(mmol/mol) = 12.0 ± 5.1) than the host coral skeletal aragonite (Sr/Ca(mmol/mol) = 9.9 ± 1.3; Mg/Ca(mmol/mol) = 4.5 ± 2.3), thus providing a serious challenge for Sr/Ca or Mg/Ca based sea surface temperature calculations. This study illustrates that many diagenetic changes that can radically alter important geochemical characteristics of coral skeleton occur very early on the sea floor (i.e., while corals are still alive). Documented cements altered trace element inventories (e.g., Sr and Mg), thus, interfering with the use of those elements in palaeotemperature calculations. Hence, significant diagenetic changes that jeopardise palaeoclimate data do not require long-term diagenesis or meteoric exposure. Some of the diagenetic changes (e.g., calcite filled borings) occur at scales that are very difficult to detect short of visual inspection using SEM. Hence, vetting of coral samples with SEM is required before any sample is subjected to geochemical analysis.

Although termites serve the ecologically important function of converting dead trees into organic matter, they annually cause damage worth billions of dollars to human structures such as houses, power poles and bridges throughout the world. This led to the development of various chemical and physical measures that primarily aimed at preventing the termites from causing damage to wooden structures. While the adverse effects of the chemical methods on the environment and human health has made them widely unacceptable, physical methods are costly and difficult to implement. There is a specific need to develop an environment friendly, cost effective, easily applicable and durable alternative barrier that would effectively protect a wide range of wooden structures. This study aims at designing and developing an eco-friendly, robust and easy to apply barrier material to protect wooden structures. Ether polyurethane (EPU) was chosen as the base material considering its toughness, resilience, hydrolytic stability due to the presence of ether group and easy applicability on large, irregular surfaces. EPU was upgraded to a ‘termite effective’ material by the incorporation of a synthetic pyrethroid, Bifenthrin®. Bifenthrin® was chosen over other termiticides due to its less pervasive nature to the environment along with its repellent/ killer effect on termites. The EPU/ Bifenthrin® system incorporates the specific features of durability of the polymer and slow release of Bifenthrin®, making it more acceptable to the environment and public health. Termite damage resistance of EPU was analyzed by testing the polymer, along with various other polymers (HDPE, PP, PVC and Nylon), with Coptotermes acinaciformes and correlating the termite properties (mandibular force, hardness) with those of the polymeric materials (surface and tensile properties). EPU resisted termite damage, though its softer form incurred 5 times more material damage than the robust cast type. EPUs with high values of hardness incurred ~40% less damage than HDPE and were comparable with the damages on PP. The depth and width of termite damage on HDPE was 5 and 4 times, respectively, than that of PVC. This part of the study inferred that, although hardness of polymeric materials helps prevent termite damage, toughness and resilience too can make it difficult for termites to find a pathway through the material. XPS, FTIR, termite mortality bioassays in an applied setting and elusion tests of Bifenthrin® from EPU in water, acetone and soil were employed to understand the interaction of EPU with Bifenthrin®. Water and soil were chosen as test mediums due to their practical nature. These studies confirm that Bifenthrin® at concentrations as low as 0.5 wt% enriches the surface of EPU due to preferential migration of CF3 group to the surface of EPU. Furthermore, Bifenthrin® incorporated in EPU does not compromise its insecticidal activity and diffuses in a controlled manner at the rate of ~10–8 cm2 s–1 and ~10–7 cm2 s–1 when kept in water and soil media respectively. The durability of EPU/ Bifenthrin® system was analyzed by conducting degradation studies on EPU. The effect of Bifenthrin® on the ageing of EPU was also investigated. The studies involved ageing of the system in natural and accelerated conditions and validating the results by use of Arrhenius models. The sub-soil conditions do not degrade EPU beyond the oxidative levels as the activation energy required to cause changes in properties of EPU are unphysically small (0.02 kJ mol-1). It was found that EPU can sustain its physical integrity for 12 years at room temperature and Bifenthrin® may remain in a 5 mm thick barrier material for up to 10 years. The effect of Bifenthrin® on the tensile properties of EPU is negligible. Studies to analyze the performance of the barrier material, involved testing of timber coated with the EPU/ Bifenthrin® system under real-life conditions against termites in field trials located at two tropical locations in Northern Queensland. EPU/ Bifenthrin® system with nominal concentrations of Bifenthrin® incurred no damage when the concentration of Bifenthrin® was above 0.07 wt% in EPU. The degradation of Bifenthrin® under sub-soil conditions is unlikely. Given that favourable characteristics of EPU and Bifenthrin® the design and development an effective and long-lasting termite barrier material seems feasible.

Although termites serve the ecologically important function of converting dead trees into organic matter, they annually cause damage worth billions of dollars to human structures such as houses, power poles and bridges throughout the world. This led to the development of various chemical and physical measures that primarily aimed at preventing the termites from causing damage to wooden structures. While the adverse effects of the chemical methods on the environment and human health has made them widely unacceptable, physical methods are costly and difficult to implement. There is a specific need to develop an environment friendly, cost effective, easily applicable and durable alternative barrier that would effectively protect a wide range of wooden structures. This study aims at designing and developing an eco-friendly, robust and easy to apply barrier material to protect wooden structures. Ether polyurethane (EPU) was chosen as the base material considering its toughness, resilience, hydrolytic stability due to the presence of ether group and easy applicability on large, irregular surfaces. EPU was upgraded to a ‘termite effective’ material by the incorporation of a synthetic pyrethroid, Bifenthrin®. Bifenthrin® was chosen over other termiticides due to its less pervasive nature to the environment along with its repellent/ killer effect on termites. The EPU/ Bifenthrin® system incorporates the specific features of durability of the polymer and slow release of Bifenthrin®, making it more acceptable to the environment and public health. Termite damage resistance of EPU was analyzed by testing the polymer, along with various other polymers (HDPE, PP, PVC and Nylon), with Coptotermes acinaciformes and correlating the termite properties (mandibular force, hardness) with those of the polymeric materials (surface and tensile properties). EPU resisted termite damage, though its softer form incurred 5 times more material damage than the robust cast type. EPUs with high values of hardness incurred ~40% less damage than HDPE and were comparable with the damages on PP. The depth and width of termite damage on HDPE was 5 and 4 times, respectively, than that of PVC. This part of the study inferred that, although hardness of polymeric materials helps prevent termite damage, toughness and resilience too can make it difficult for termites to find a pathway through the material. XPS, FTIR, termite mortality bioassays in an applied setting and elusion tests of Bifenthrin® from EPU in water, acetone and soil were employed to understand the interaction of EPU with Bifenthrin®. Water and soil were chosen as test mediums due to their practical nature. These studies confirm that Bifenthrin® at concentrations as low as 0.5 wt% enriches the surface of EPU due to preferential migration of CF3 group to the surface of EPU. Furthermore, Bifenthrin® incorporated in EPU does not compromise its insecticidal activity and diffuses in a controlled manner at the rate of ~10–8 cm2 s–1 and ~10–7 cm2 s–1 when kept in water and soil media respectively. The durability of EPU/ Bifenthrin® system was analyzed by conducting degradation studies on EPU. The effect of Bifenthrin® on the ageing of EPU was also investigated. The studies involved ageing of the system in natural and accelerated conditions and validating the results by use of Arrhenius models. The sub-soil conditions do not degrade EPU beyond the oxidative levels as the activation energy required to cause changes in properties of EPU are unphysically small (0.02 kJ mol-1). It was found that EPU can sustain its physical integrity for 12 years at room temperature and Bifenthrin® may remain in a 5 mm thick barrier material for up to 10 years. The effect of Bifenthrin® on the tensile properties of EPU is negligible. Studies to analyze the performance of the barrier material, involved testing of timber coated with the EPU/ Bifenthrin® system under real-life conditions against termites in field trials located at two tropical locations in Northern Queensland. EPU/ Bifenthrin® system with nominal concentrations of Bifenthrin® incurred no damage when the concentration of Bifenthrin® was above 0.07 wt% in EPU. The degradation of Bifenthrin® under sub-soil conditions is unlikely. Given that favourable characteristics of EPU and Bifenthrin® the design and development an effective and long-lasting termite barrier material seems feasible.

Trajectories of decline have been described in coral reefs throughout the Indo-Pacific region, with long-term losses of abundance, diversity and habitat structure. Since European settlement of the Queensland coastline in the mid-18th century, widespread changes in land use have occurred within Great Barrier Reef (GBR) catchments (e.g. extensive land clearing, agriculture and grazing). Despite direct and indirect evidence indicating decline of inshore reefs, it has proven difficult to ascertain links between land use changes, terrestrial discharge, water quality and the decline of coral reefs at regional scales, and the contributions of anthropogenic influences to the disturbance regimes of inshore reefs remains highly controversial. This thesis uses palaeoecological reconstruction of coral assemblages and high-precision U-Series dating to examine changes in community structure of inshore coral reefs in the Palm Islands region across decadal and centennial scales. Comparisons of modern and historical coral assemblages provide evidence of a collapse of Acropora coral communities at Pelorus Reef in the early 20th Century. Fossil assemblages in an adjacent site at Pelorus provide further evidence of an extrinsic shift from historical Acropora assemblages to more sediment-tolerant corals in modern assemblages, a change without precedence in 800 years of record. Sediment cores (2-5m length) were extracted from Pandora and Havannah reefs to determine long-term rates of reef growth throughout the late Holocene. Computer Axial Tomography (CAT) scans of cores revealed a framework dominated by coral fragments, and U-Series dating of corals revealed rapid and continuous reef growth at both reefs throughout the last 1000 yrs. Comparisons of reef accretion (m ka-1) from cores with published accretion rates from early-mid Holocene inshore GBR reefs show that reef slope environments are now accreting at rates equal to and exceeding those of the last 8000 years. This result contradicts assumptions that inshore reefs are undergoing or have undergone natural trajectories of geomorphic decline. A bayesian approach to determine stability of coral communities from the Pandora and Havannah cores indicates that those coral communities have existed in stable states for upwards of 400yrs, punctuated by periods of instability. Contrary to some paradigms of biodiversity, the high diversity communities were unstable on centennial scales, 4 yet the low diversity assemblages did not necessarily confer stability to these assemblages. Growth rates of inshore reefs were independent of diversity or community structure. From a management perspective, these results provide a longer-term (decades to centuries) understanding of coral community dynamics on inshore reefs of the GBR that provides a basis for detecting and understanding changes following European settlement, and a baseline for the management and potential restoration of coral communities at local and regional scales.

No abstract available

West Nile Virus (WNV) has emerged as a major cause of viral encephalitis. Since its outbreak in the United States 27,000 people have presented with clinical WNV disease resulting in 1074 fatalities. WNV causes a range of disease from mild febrile illnesses to severe and fatal encephalitis. To date, there are currently no therapeutic agents or vaccines available to treat WNV infection in humans. In order to address this, a better understanding of the mechanisms responsible for viral neuroinvasion and neuropathology are required. Using a range of in vitro and in vivo studies, we have investigated the routes by which WNV enters the CNS. Virus replication was observed in the brain microvascular endothelial cells in mice that succumbed to WNV encephalitis. Moreover, we demonstrated that infection of a polarized HBMEC with WNV induced apoptosis. Microarray analysis of WNV-infected HBMEC’s revealed that WNV elicited the expression of cytokines that have been shown to contribute to permeablization of the BBB. These findings suggest that WNV can enter the CNS through the BBB via multiple mechanisms. Real-time RT-PCR performed on WNVinfected HBMECs identified two host genes involved in the host cellular anti-oxidant response that were differentially regulated during viral infection. Furthermore, the addition of the antioxidant, N-acetylcysteine, restored cell viability and decreased viral replication, indicating that oxidative stress contributes to WNV-induced pathogenesis. The current state of knowledge regarding the pathogenesis of WNV encephalitis is based on studies that have defined the role of systemic immune responses to WNV. Limited investigations have been undertaken to determine the contribution of brain cells in the defence, or damage to the brain once WNV has gained access to the CNS. Real-time RT-PCR results in conjunction with in vivo CBA assay data, suggested several candidate host genes that could contribute to the pathogenesis of WNV. Thus, it is necessary to further define the mechanisms of WNV induced pathogenesis as this will aid in the development of targeted strategies to prevent neurological infection and mitigate neurological diseases in affected individuals.

The mixed sand and gravel barrier beaches located on the South Island's East Coast are formed predominantly of Greywacke, eroded from the mountains, and transported via the major river systems. These barriers act as the interface between the South Pacific Ocean and the surrounding hinterland. In times of high energy coastal events, breaching is common. This thesis examines the form and function of the Waihao-Wainono barrier, a section of the coastline situated north of the Waitaki River. Breaches along this part of the barrier are frequent and several have rendered the surrounding farmland unusable for several years due to the effects of saltwater inundation. There is some concern among the local community as to exactly why the barrier breaches at certain locations and not others, making land planning and management a difficult task for farmers. Several of the local landowners believe that since the construction of the Waitaki Dam in 1935, a significant decrease in sediment size along the barrier has occurred. It is also thought that the barrier form has experienced substantial change. Through the use of physical techniques used in the field of coastal science, 17 sites along the Waihao-Wainono barrier were studied. Excavations were carried out, surface and substrate profiles recorded and sediment samples collected from the surface. sub-surface and substrate of the barrier. Analysis of the barrier form and barrier volume concluded that the past breach sites consisted of steeper lower foreshore slopes than the non-breach sites, and at two sites, the substrate was not reached. Breach areas display the greatest barrier volume of all the study sites, which is contrary to belief. In relation to the surface sediments, the majority of barrier profiles displayed the distinct mean grain size cross shore zonation, characteristic of mixed sand and gravel beaches. The best and most consistent surface sorting was also identified as being a characteristic of the breach sites. The sediment size is not shown to have drastically reduced over the thirty year sampling period as was perceived by the local community. Within the sub-surface of the barrier, the sediments displayed chaotic sizes and generally poorly sorted material. Several of the breach sites contained a distinct change in sediment size between the coarser surface layer and the finer layer located immediately below. This layering of coarse and fine sized sediments leads to differences in permeability within the barrier, which is thought to be a major factor in why these sites have breached. Resulting from these findings, a group of characteristics of breach sites was formed and several predictions made as to where the barrier may breach in the near future.

This study examines the biology of the venus tuskfish Choerodon venustus from the southern Great Barrier Reef to enable better-informed management decisions. Venus tuskfish are taken almost exclusively by line fishing. The size of the catch is uncertain, but the annual Queensland commercial catch is probably about 30 t and the recreational catch much greater than this (possibly ca. 300 t). The species is not the primary target of fishers and can be regarded as by-catch taken while targeting other species. However C. venustus is the second or third most commonly retained species in the study area. Venus tuskfish are taken in habitats associated with coral and other reefs across a depth range from 5 m to 90 m. The species is a benthic predator, taking molluscs, echinoderms, annelids, arthropods, and fish (in decreasing order of importance). Feeding intensity was greatest in summer. There was evidence of complex feeding behaviours and a dominance hierarchy amongst feeding fish that may result in large males being more susceptible to fishing. The species is slow growing and long lived. Up to 38 bands were observed on the opercular bones of C. venustus. Back-calculation methods yielded von Bertalanffy growth parameters of L¥ =669 mm, K = 0.09 and t0 = -3.89. Male fish appear to grow faster than females. This may be related either to faster growing fish becoming males, growth acceleration following sex reversal, or both. Selective removal of faster growing males in heavily fished locations may result in a greater proportion of slower growing females in the remaining population. iv Choerodon venustus is a protogynous hermaphrodite; the proportion of males increases as the fish increase in size, transitional fish exist and remnant female tissue was evident in testes. The species is a serial spawner with an extended breeding season perhaps peaking in autumn and around the new and full moon. Females mature between 200 and 250 mm forklength (LCF). Venus tuskfish display sexually dimorphic colouration and appear to have a socio-sexual group structure. Fish occur in extended groups with several large males associated with a larger number of smaller females. Multiple sex-reversals may occur in the groups perhaps in response to the loss of the larger males. Large females produce over 100,000 eggs in the ovaries. The number of eggs released at each spawning is unknown. There is a direct cubic relationship between length and the weight of female gonads. Large females over 500 mm LCF are capable of producing over 20 times the number of eggs of small mature females (around 250 mm LCF). The locations sampled showed marked differences in fishing effort. The Capricorn Bunker Group was subject to much higher fishing effort than the Swains Reefs. Estimates of fishing mortality reflected this trend. Line fishing selects large male fish. The heavily fished Masthead Island had smaller males, females and transitional fish. Fish below 300 mm LCF were not captured efficiently. Venus tuskfish may be capable of modifying their life cycle in response to increased fishing mortality. Sex reversal may be related to the absence of large males in social groups. Hence sex ratio remains constant between fished and unfished locations. In heavily fished populations, females are smaller and consequently produce fewer eggs. Modeling suggests unfished areas may have a potential fecundity over six times that of those heavily exploited. Choerodon venustus are severely impacted by barotrauma during capture, and few captured and released fish are likely to survive. There are special challenges in managing venus tuskfish including: · Their status as a largely bycatch species; · The poor survival of released fish due to barotrauma; · A lack of good measures of catch and effort caused by inconsistent naming of the species and inherent errors in current data collection methods; · Their extended spawning period and likely widespread spawning sites and · The need to support group fecundity by protecting larger fish. A combination of a series of fish reserves, raising the minimum legal size to 36 cm TL, effective catch limits and an effective education program are likely to support the sustainability of the fishery.

Thesis ( Ph.D. ) -- McMaster University, 1997. / Includes bibliographical references (p. 190-197) Also available via World Wide Web.