Resource Management and Geography - Research Publications
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ItemThe First Isolation and Characterisation of the Protist Labyrinthula sp in Southeastern Australia(WILEY, 2017-07)As a result of anthropogenic influences and global climate change, emerging infectious marine diseases are thought to be increasingly more common and more severe than in the past. The aim of our investigation was to confirm the presence of Labyrinthula, the aetiological agent of the seagrass wasting disease, in Southeastern Australia and provide the first isolation and characterisation of this protist, in Australia. Colonies and individual cells were positively identified as Labyrinthula using published descriptions, diagrams, and photographs. Their identity was then confirmed using DNA barcoding of a region of the 18S rRNA gene. Species level identification of isolates was not possible as the taxonomy of the Labyrinthula is still poorly resolved. Still, a diversity of Labyrinthula was isolated from small sections of the southeast coast of Australia. The isolates were grouped into three haplotypes that are biogeographically restricted. These haplotypes are closely related to previously identified saprotrophic clades. The study highlights the need for further investigation into the global distribution of Labyrinthula, including phylogenetic pathogenicity and analysis of host-parasite interactions in response to stressors. Given the results of our analyses, it is prudent to continue research into disease and epidemic agents to better prepare researchers for potential future outbreaks.
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ItemEnvironmental effects on germination phenology of co-occurring eucalypts: implications for regeneration under climate change(SPRINGER, 2015-09)Germination is considered one of the important phenological stages that are influenced by environmental factors, with timing and abundance determining plant establishment and recruitment. This study investigates the influence of temperature, soil moisture and light on the germination phenology of six Eucalyptus species from two co-occurring groups of three species representing warm-dry and cool-moist sclerophyll forests. Data from germination experiments were used to calibrate the germination module of the mechanistic model TACA-GEM, to evaluate germination phenology under a range of climate change scenarios. With the exception of E. polyanthemos, the optimal niche for all species was characterised by cool-moist stratification, low light, cool temperatures and high soil moisture. Model results indicated that of the warm-dry species, Eucalyptus microcarpa exhibited greater germination and establishment under projected changes of warmer drier conditions than its co-occurring species Eucalyptus polyanthemos and Eucalyptus tricarpa which suggests that E. microcarpa could maintain its current distribution under a warmer and drier climate in southeastern Australia. Among the cool-moist species, Eucalyptus radiata was the only species that established under projected climate change of the 2080s but at such a low probability that its persistence compared to Eucalyptus obliqua and Eucalyptus sieberi cannot be posited. For all cool-moist species, germination did not benefit from the phenological shifts they displayed. This study successfully demonstrated environmental effects on germination phenology and how a shift in climate can influence the timing and success of recruitment.
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ItemIwao's patchiness regression through the origin: biological importance and efficiency of sampling applications(WILEY, 2014-04)Abstract Iwao's mean crowding‐mean density relation can be treated both as a linear function describing the biological characteristics of a species at a population level, or a regression model fitted to empirical data (Iwao's patchiness regression). In this latter form its parameters are commonly used to construct sampling plans for insect pests, which are characteristically patchily distributed or overdispersed. It is shown in this paper that modifying both the linear function and statistical model to force the intercept or lower functional limit through the origin results in more intuitive biological interpretation of parameters and better sampling economy. Firstly, forcing the function through the origin has the effect of ensuring that zero crowding occurs when zero individuals occupy a patch. Secondly, it ensures that negative values of the intercept, which do not yield an intuitive biological interpretation, will not arise. It is shown analytically that sequential sampling plans based on regression through the origin should be more efficient compared to plans based on conventional regression. For two overdispersed data sets, through‐origin based plans collected a significantly lower sample size during validation than plans based on conventional regression, but the improvement in sampling efficiency was not large enough to be of practical benefit. No difference in sample size was observed when through‐origin and conventional regression based plans were validated using underdispersed data. A field researcher wishing to adopt a through‐origin form of Iwao's regression for the biological reasons outlined above can therefore be confident that their sampling strategies will not be affected by doing so.
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ItemThe effect of urban ground covers on arthropods: An experiment(SPRINGER, 2014-03)
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ItemEcological functions of zoosporic hyperparasites.(Frontiers Media SA, 2014)Zoosporic parasites have received increased attention during the last years, but it is still largely unnoted that these parasites can themselves be infected by hyperparasites. Some members of the Chytridiomycota, Blastocladiomycota, Cryptomycota, Hyphochytriomycota, Labyrinthulomycota, Oomycota, and Phytomyxea are hyperparasites of zoosporic hosts. Because of sometimes complex tripartite interactions between hyperparasite, their parasite-host, and the primary host, hyperparasites can be difficult to detect and monitor. Some of these hyperparasites use similar mechanisms as their parasite-hosts to find and infect their target and to access food resources. The life cycle of zoosporic hyperparasites is usually shorter than the life cycle of their hosts, so hyperparasites may accelerate the turnaround times of nutrients within the ecosystem. Hyperparasites may increase the complexity of food webs and play significant roles in regulating population sizes and population dynamics of their hosts. We suggest that hyperparasites lengthen food chains but can also play a role in conducting or suppressing diseases of animals, plants, or algae. Hyperparasites can significantly impact ecosystems in various ways, therefore it is important to increase our understanding about these cryptic and diverse organisms.
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ItemA new cost-effective method to mitigate ammonia loss from intensive cattle feedlots: application of lignite(NATURE PORTFOLIO, 2015-11-20)In open beef feedlot systems, more than 50% of dietary nitrogen (N) is lost as ammonia (NH3). Here we report an effective and economically-viable method to mitigate NH3 emissions by the application of lignite. We constructed two cattle pens (20 × 20 m) to determine the effectiveness of lignite in reducing NH3 emissions. Twenty-four steers were fed identical commercial rations in each pen. The treatment pen surface was dressed with 4.5 kg m(-2) lignite dry mass while no lignite was applied in the control pen. We measured volatilised NH3 concentrations using Ecotech EC9842 NH3 analysers in conjunction with a mass balance method to calculate NH3 fluxes. Application of lignite decreased NH3 loss from the pen by approximately 66%. The cumulative NH3 losses were 6.26 and 2.13 kg N head(-1) in the control and lignite treatment, respectively. In addition to the environmental benefits of reduced NH3 losses, the value of retained N nutrient in the lignite treated manure is more than $37 AUD head(-1) yr(-1), based on the current fertiliser cost and estimated cost of lignite application. We show that lignite application is a cost-effective method to reduce NH3 loss from cattle feedlots.
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Item"Cryptic" diagenesis and its implications for speleothem geochronologies(Elsevier, 2016-09-15)Speleothems are usually considered as one of the most amenable palaeoclimate archives for U-series dating. A number of studies in recent years, however, report cases of diagenetic alteration which compromises the use of U-series systematics in speleothems, resulting in inaccurate U-Th ages. Here we present the results of a high-resolution U-Th dating study of a stalagmite (CC26) from Corchia Cave in Italy where we document a number of departures from an otherwise well-defined age-depth model, and explore potential causes for these outliers. Unlike examples illustrated in previous studies, CC26 contains no visible evidence of neomorphism, and appears, at least superficially, ideally suited to dating. Good reproducibility obtained between multi-aliquot U-Th analyses removes any possibility of analytical issues contributing to these outliers. Furthermore, replicate analyses of samples from the same stratigraphic layer yielded ages in stratigraphic sequence, implying very localized open-system behavior. Uranium loss is suggested as a causative mechanism on account of the fact that all the outliers are older than their assumed true age. A limited number of micro-voids were observed under micro-CT analyses, and it is proposed that these were pathways for U loss. Uranium-loss modelling allows us to constrain the possible timing of diagenetic alteration and indicates that the precursor for the outlier with the largest age discrepancy (309%) must have been aragonite. This study indicates that visibly unaltered speleothems may still contain small domains that have experienced post-depositional alteration. Such “cryptic” diagenesis, as recorded in this stalagmite, has implications for the constancy of accuracy of the U-series dating technique, and suggests a need for careful examination of speleothems prior to dating, particularly in low-resolution U-Th studies.
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ItemGovernmentality and the conduct of water: China's South-North Water Transfer Project(WILEY, 2016-10)Governmentality is a way of thinking about dispersed practices of governing, including attempts to render space governable. China's South–North Water Transfer (SNWT) project, the world's largest interbasin water transfer project, is a programme of government that attempts to render the distribution of water across space more governable and administrable. This article analyses English and Chinese academic, media and government documents through a governmentality lens. It aims to examine the SNWT project's machinery, mentality and spatiality, including its narrative, its constitution of objects and subjects in space, its multiple techniques of government, and its physical and administrative assemblages. In decentring the problem of the state in relation to the SNWT project we can learn much about both the politics of water and the nature of Chinese governmentalities. This article shows how the SNWT naturalises water scarcity, normalises the pre‐eminence of North China, sustains engineering over regulatory solutions and reconfigures hydrosocial relations, while also outlining the limits to and endemic conflicts within this vast programme of government.
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ItemNo Preview AvailableSocially just publishing: Implications for geographers and their journals(Geographical Society of Finland, 2017-12-15)There have been a range of protests against the high journal subscription costs, and author processing charges (APCs) levied for publishing in the more prestigious and commercially run journals that are favoured by geographers. But open protests across the sector like the ‘Academic Spring’ of 2012, and challenges to commercial copyright agreements, have been fragmented and less than successful. I renew the argument for ‘socially just’ publishing in geography. For geographers this is not limited to choosing alternative publication venues. It also involves a considerable effort by senior faculty members that are assessing hiring and promotion cases, to read and assess scholarship independently of its place of publication, and to reward the efforts of colleagues that offer their work as a public good. Criteria other than the citation index and prestige of a journal need to be foregrounded. Geographers can also be publishers, and I offer my experience editing the free online Journal of Political Ecology.