Dissertations / Theses on the topic 'Southwestern Australia'
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1
Edwards, Danielle L. "Biogeography and speciation of southwestern Australian frogs." University of Western Australia. School of Animal Biology, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0058.
Abstract:
[Truncated abstract] Southwestern Australia is a global biodiversity hotspot. The region contains a high number of endemic species, ranging from Gondwanan relicts to more recently evolved plant and animal species. Biogeographic models developed primarily for plants suggest a prominent role of Quaternary climatic fluctuations in the rampant speciation of endemic plants. Those models were not based on explicit spatial analysis of genetic structure, did not estimate divergence dates and may be a poor predictor of patterns in endemic vertebrates. Myobatrachid frogs have featured heavily in the limited investigations of the biogeography of the regions fauna. Myobatrachid frogs are diverse in southwestern Australia, and while we know they have speciated in situ, we know little about the temporal and spatial patterning of speciation events. In order to gain insight into the biogeographic history and potential speciation patterns of Myobatrachid frogs in the southwest I conducted a comparative phylogeography of four frog species spanning three life history strategies. I aimed to: 1) assess the biogeographic history of individual species, 2) determine where patterns of regional diversity exist using a comparative framework, 3) determine whether congruent patterns across species enable the development of explicit biogeographic hypotheses for frogs, and 4) compare patterns of diversity in plants with the models I developed for frogs. I conducted fine-scale intraspecific phylogeographies on four species. ... Geocrinia leai: deep divergences, coincident with late Miocene arid onset, divide this species into western and southeast coastal lineages, with a third only found within the Shannon-Gardner River catchments. Phylogeographic history within each lineage has been shaped by climatic fluctuations from the Pliocene through to the present. Arenophryne shows the first evidence of geological activity in speciation of a Shark Bay endemic. Divergence patterns between the High Rainfall and Southeast Coastal Provinces within C. georgiana are consistent with patterns between Litoria moorei and L. cyclorhynchus and plant biogeographic regions. Subdivision between drainage systems along the southern coast (in M. nichollsi, G. leai and the G. rosea species complex) reflect the relative importance of distinct catchments as refuges during arid maxima, similarly the northern Darling Escarpment is identified as a potential refugium (C. georgiana and G. leai). Divergences in Myobatrachid frogs are far older than those inferred for plants with the late Miocene apparently an important time for speciation of southwestern frogs. Speciation of Myobatrachids broadly relates to the onset of aridity in Australia in the late Miocene, with the exception of earlier/contemporaneous geological activity in Arenophryne. The origins of subsequent intraspecific phylogeographic structure are coincident with subsequent climatic fluctuations and correlated landscape evolution. Divergence within frogs in the forest system may be far older than the Pleistocene models developed for plants because of the heavy reliance on wet systems by relictual frog species persisting in the southwestern corner of Australia.
2
Loo, Christopher. "The ecology of naturalised silvergrass (Vulpia) populations in south-western Australia." University of Western Australia. School of Plant Biology, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0093.
Abstract:
[Truncated abstract] Annual grasses have colonised a diverse range of environments in southern Australia. The “Silvergrasses” of the genus Vulpia are excellent examples being widely distributed, are prevalent weeds of agriculture and have had a long history to naturalise on the continent. Research was undertaken on Vulpia populations to identify if naturalising species have reproductive traits that provide propagules with the best chances of success. Furthermore, research aimed at investigating if these traits vary between species and their populations and how this variability related to the environment. A herbarium and field study was undertaken to establish what Vulpia species occur in SW Australia and to investigate environmental factors affecting their distribution. 169 herbaria specimens was examined and a botanical field survey of 189 sites was carried out in September 1998. Four species occur in the region: V. fasciculata, V. muralis, V. bromoides and two variants of V. myuros (V. myuros var. megalura and V. myuros var. myuros). V. bromoides and V. myuros were introduced early into the region while V. fasciculata and V. muralis more recently. It is plausible that Vulpia invaded the region via early seaport settlements and was spread by agricultural expansion. 96% of field sites contained V. myuros var. myuros, 79% V. myuros var. megalura, 50% V. bromoides, 6% V. fasciculata and 6% contained V. muralis. 90% of sites contained a mix of species and 9% of sites contained pure species stands. V. myuros var. myuros is the most widespread species and dominant form of V. myuros. It is found from high rainfall regions through to arid locations occurring on mostly light textured low fertility soils. V. muralis and V. fasciculata occur infrequently with the former widely dispersed and the later occurring predominantly on sands. V. bromoides occurs extensively in high rainfall regions but rarely extends to locations receiving less than 400-450mm annual rainfall and northward above 30°00’ latitude. It is predominantly on light to loamy textured soils that are fertile and acid. The most common species V. myuros and V. bromoides often coexist within sites but the dominance of one over the other is strongly correlated with growing season length and false break frequency. V. bromoides is positively correlated to growing season length and V. myuros is negatively related. The distribution of Vulpia species is strongly influenced by climate and soils. Variability in distribution is a reflection of the ecological differentiation between species to colonise different environments
3
Dolling, Perry. "Lucerne (Medicago sativa) productivity and its effect on the water balance in southern Western Australia." University of Western Australia. Faculty of Natural and Agricultural Sciences, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0108.
Abstract:
[Truncated abstract] In southern Western Australia the replacement of deep-rooted native vegetation with annual species has resulted in rising water tables and increased salinity due to insufficient water use. The area has a Mediterranean-type climate where rainfall during summer is generally low but variable resulting in limited plant growth. However, if rainfall does occur it potentially can contribute to to the increased water excess or drainage by increasing the soil water content before the main drainage period in winter. The first study investigated factors controlling soil water content changes during the fallow (December to May) in annual farming systems. This was achieved by examining variation in available soil water storage to a depth of 1.0-1.5 m at three sites within 13 seasons. Reasons for the variation were examined using the Agricultural Production Systems Simulator (APSIM). This study also investigated the relationship between soil water content at the end of the fallow period (1 May) and the amount of drainage below 2.5 m by using APSIM coupled to historical weather records at three locations. At the end of the fallow a mean of 24 mm (or 25%) of rainfall during the fallow was retained in the soil. Losses of soil water during the fallow were due to evaporation (mean of 60 mm), transpiration from plant cover (mean of 12 mm) and drainage below the root zone and run off (combined mean of 13 mm). Soil water accumulation during the fallow period had a significant impact on simulated drainage under wheat in the following growing season. Every 1 mm increase in soil wetness at the end of the fallow resulted in a 0.7-1 mm increase in simulated drainage during the growing season. ... Variation in the water excess due to variation in rainfall was greater than the reduction in water excess due to lucerne. This makes the decisions about when to grow lucerne to reduce water excess difficult if livestock enterprises are less profitable than cropping enterprises. The findings of this PhD indicate that lucerne does have a place in Mediterranean-type environments because of its greater water use than current farming practices. However, its use needs to be strategic and the strategy will vary from region to region. For example, in the low rainfall region lucerne sowings need to be matched with high soil water contents and phase length will generally be short (2-3 years). In comparison at high rainfall regions lucerne will need to be grown for longer or combined with other strategies to increase water use.
4
Bhatti, Muhammad Ali. "Genetic variation in naturalized wild radish (Raphanus raphanistrum L.) populations in the mediterranean climate of south-western Australia." University of Western Australia. School of Plant Biology, 2004. http://theses.library.uwa.edu.au/adt-WU2005.0012.
Abstract:
[Truncated abstract] Wild radish (Raphanus raphanistrum L.), an outcrossing annual plant, is one of the most widespread and successful colonising weeds in the Australian wheat belt. It was introduced accidentally during the latter part of the 19th century, apparently independently through the major ports of southern Australia. The widespread success of wild radish, and therefore the likelihood of distinct populations, gives us the opportunity to study the colonizing process with adaptation in annual outbreeding species, and to explore their genetic diversity. The aims of this thesis were to study the genetic diversity of wild radish and to investigate which factors are important in its success. After an initial review of the literature (chapter 2), the thesis describes experiments where genetic variation between and within populations was compared at 55 sites in transects across the wheat belt and high rainfall zones of temperate Western Australia (chapter 3). In chapter 4, variation in life history traits was compared with variation in AFLP molecular markers. The role of seed dormancy in the survival of the species was examined in chapter 5, and variation in the oil content of seeds and their fatty acid composition was examined in chapter 6. Finally, the results were discussed in chapter 7 with special reference to the adaptive value of outcrossing in annual weeds. The results suggest that wild radish has evolved to fit the Australian environment. However, measurement of 14 morphological and phenological characters showed that in most cases within site variation was much greater than that between sites. Most of the variation between sites was associated with geoclusters, a name given to zones of similar environmental conditions in regard to rainfall and temperature. Thus plants from areas with high rainfall and low temperature produced longer, wider pods with more segments, heavier seeds and flowered later than plants from more arid areas.
5
Callow, John Nikolaus. "River response to land clearing and landscape salinisation in southwestern Australia." University of Western Australia. School of Earth and Geographical Sciences, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0085.
Abstract:
[Truncated abstract] Land clearing is known to increase runoff, and in many dryland landscapes is also associated with rising saline watertables, causing increased stream salinity and degrading riparian vegetation. The limited understanding of how river morphology responds to these changes and the potential for vegetation-based strategies to offer river management options under these conditions, has prompted this research. In southwestern Australia the severity of salinity and recent nature of land clearing provides an appropriate setting to investigate river response. A data-based, multidisciplinary methodology was applied to determine how land clearing and landscape salinisation has altered landscape sensitivity through changes in erosive potential, system connectivity and material threshold mechanisms, and how these affect patterns of river response. The study investigated the responses of morphologically similar reaches across fifty two study sites in the Kent River and Dalyup River catchments, in the south coastal rivers region of Western Australia. Land clearing was found to have significantly altered the hydrologic regime and erosive potential in both frequency and magnitude, with flow becoming more perennial, and increased annual discharge, flood peaks and bankfull flow frequency. While sediment transport rates have also increased since land clearing, they remain low on a global scale. Human response to a reduced rainfall regime and related water security pressures has caused large hillslope areas to be decoupled from the main channels by bank and farm dam construction, and have reduced downstream transmission of change. ... By contrast, steeper-sloped mid-catchment areas with minimal vegetation degradation caused by salinity are associated with higher erosive potential. A more erosive response is observed in these reaches where floodplains have been cleared for agricultural purposes. A conceptual model of vegetation growth across the salinity gradient observed in the study catchments was developed, and applied to selected river styles to assess the potential that vegetation-based strategies offer for river management. This work identifies the unsuitability of river restoration strategies, but the potential for river restoration or remediation in a saline landscape. Hydraulic modelling demonstrated that river rehabilitation strategies such as improving the vegetation condition of the riparian buffer using native or commercial species on areas elevated above saline flow can stabilise reaches. For river styles in wide and flat valleys, there is limited potential for vegetation-based river rehabilitation under the current salinity gradient. Field observation and modelling suggest that river remediation may offer geomorphic management options in salt-affected reaches through channelisation to lower watertables, and further research on this is warranted. This work found a consistent response for river styles across the two study catchments. Based on the understanding of river response and the potential for vegetation-based river management for each style, this research offers a regional-scale tool for river management in a saline landscape.
6
Shahrestani, Nakisa. "An ecological characterisation of a shallow seasonal claypan wetland, Southwestern Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2017. https://ro.ecu.edu.au/theses/2045.
Abstract:
Perched, seasonal claypans of southwestern Australia are poorly understood in terms of their ecological character, such as relationship between hydrology and their biota. An example is Little Darkin Swamp, located on the Darling Plateau in southwestern Australia. The overall aim of this thesis was to describe its ecological character, to understand what drives this claypan system and how its ephemeral nature affects wetland processes and functions.
This study first comprised a detailed characterisation of the wetland’s attributes, following the geomorphic-hydrological approach proposed by Semeniuk and Semeniuk (2011). This revealed that its hydrology is highly dependent on rainfall, that it is an endorheic system, with a basin that is structurally spatially heterogeneous with distinct vegetation zones, and that surface waters have nutrient levels that are similar to oligotrophic systems. These features make it similar to other claypan wetlands of southwestern Australia and vernal pools of California, USA.
Continuous high-frequency dissolved oxygen data during the hydroperiod showed that there are large temporal and spatial variations in ecosystem metabolism, and that the trophic status of the wetland is finely balanced, fluctuating between auto- and heterotrophy due to its ephemeral nature. Due to its oligotrophic nature, rates of gross primary production (GPP) and respiration (R) were overall low, and the wetland was overall slightly autotrophic over the study period. Furthermore, dual isotope analysis of δ13C and δ15N of sources and consumers revealed that aquatic macrophytes make a higher contribution to the food web compared to other sampled sources. However, the food web was also supported by sources of carbon that were not sampled, probably filamentous algae and methanotrophic bacteria.
Experimental re-hydration of dried sediments emphasized that the seasonality of the water regime, and the shallow bathymetry of the basin, influences organic matter content, nutrient levels, oxygen consumption, plant growth and macroinvertebrate richness, differently between the centre of the wetland versus the edges. These results confirmed that there are at least two distinct zones in the wetland in terms of biotic response following rewetting, caused by the differences in duration and frequency of inundation of the sediments.
The outcomes of this study showed that the ephemerality (i.e. seasonal drying and wetting) of Little Darkin Swamp drives important internal ecosystem processes, such as ecosystem metabolism, nutrient cycling, and primary production, which in turn determine the trophic status and distribution of biotic communities in the wetland. Therefore, any changes to the hydrological regime will greatly affect how these system functions and can potentially negatively impact such unique shallow, seasonal perched systems of southwestern Australia.
7
Smith, Russell Stephen. "The ecology of two rare Chamelaucium species (Myrtaceae) from Southwestern Australia." Thesis, Smith, Russell Stephen (1994) The ecology of two rare Chamelaucium species (Myrtaceae) from Southwestern Australia. Masters by Research thesis, Murdoch University, 1994. https://researchrepository.murdoch.edu.au/id/eprint/51903/.
Abstract:
Studies were carried out into various aspects of the ecology of Chamelaucium erythrochlorum m.s. and C. roycei m.s. (Myrtaceae), two declared rare and endangered shrubs restricted to the south west of Western Australia. Initially a soil and vegetation survey was a carried out at the site of all known populations of C erythrochlorum and C. roycei and at some nearby environmentally similar areas where the species did not occur. In addition, aspects of the water relations, phenology and reproductive biology of both species was investigated. Measurements of various floral characters and leaf length were compared for a number of the populations of C. erythrochlorum.
Chamelaucium erythrochlorum was found on a range of soils from the infertile gravelly soils at Dardanup Block near Bunbury to fertile red-brown alluvial loams at the Yoongarillup site near Busselton. The soil of the C. roycei sites in the Tutunup-Ruabon area near Busselton varied from moderately acid, brown sandy loams to red-brown loams over a sheet laterite hardpan at a shallow depth.
Classification of the C. erythrochlorum quadrats produced four community groups, determined primarily by understorey species composition. These groups were partly based on geographic factors and partly on topographic position. All quadrats were in the Eucalyptus marginata - E. calophylla or E. marginata - E. haemotoxylon forest structural type.
Classification of the C. roycei sites and other heathland sites, produced three vegetation groups, with two of the groups containing C. roycei. All of the vegetation groups are structurally mid-dense to dense heathland 0.5 to 1.2 metres high with occasional emergents to 3 metres.
Studies into the water relations of C. erythrochlorum, Bossieaea omata and Hypocalymma robustum at Dardanup Block showed that pre-dawn xylem pressure potentials (XPP) were not significantly different between the three species within the C. erythrochlorum "band" in either summer or autumn. C. erythrochlorum was apparently not restricted to this "band" because of increased moisture availability to the adult plants.
Mid-morning XPP only was measured at the C. roycei site (Tutunup), where C. roycei had the second lowest XPP of the six species measured although it was not significantly different from any of them. Some of the heathland species, but not C. roycei, showed no fall in late-moming XPP between December and March which indicates that they were probably accessing abundant water below the laterite hardpan.
Shoot growth of C. erythrochlorum in 1992/93 at Sabina River started in mid July which was about two weeks earlier than at Dardanup. Flowering was also more advanced at Sabina River (August compared to December) and the flowering season lasted considerably longer (until May) than at Dardanup Block where it finished in February.
More plants in the long-unburnt area at Sabina River produced flowers than in the recently burnt area, and they also produced more flowers per plant. In contrast to those at Sabina River very few of the C. erythrochlorum plants monitored at Dardanup Block flowered over the three seasons of the study.
Many of the flowers of C. erythrochlorum at Sabina River were damaged by ant grazing in February. The damage in most cases was caused by the insect chewing a hole in the ovary or eating part of the stamen or petals. Compared to Sabina River there was very little insect grazing of C. erythrochlorum at Dardanup Block.
All adult plants censused at Sabina River survived over the two and a half years of the study. However 15% of the monitored plants at Dardanup Block had died by the end of October 1993. Most of the plant deaths occurred in late autumn or early winter, primarily from the effects of the summer/autumn drought.
Shoot growth in C. roycei started in June and extended through to late January. Flower formation, which was prolific, tended to coincide with shoot growth and plants in the wetter area had the longest flowering season.
By February 1992 almost three quarters of the adult C. roycei at Tutunup had died, apparently from drought. All of the seedlings in the burnt area at Tutunup died in mid-summer while only 17.5% of the seedlings on the railway embankment did so probably because those on the embankment were more mature.
A leaf and floral morphometric study showed that the populations of C. erythrochlorum could be split into those with larger flowers with longer styles and those with smaller flowers with shorter styles. The flowers at Dardanup Block are intermediate between the two groups. The C. erythrochlorum populations can also be split into two groups in regard to leaf length.
A study of ovule and pollen numbers in both rare species showed that the most common number of ovules/flower for C. roycei is 8 (62% of flowers) and that for C. erythrochlorum is 9 (37%) though 10 and 8 ovules/flower were also quite common. In C. erythrochlorum from Sabina River the lower ring of anthers had 20 to 30% more pollen grains than the upper anthers. There was a large difference in the proportion of apparently inviable pollen between the large-flowered and small-flowered types.
The total number of pollen grains per ovule (pollen/ovule ratio) for C. erythrochlorum was about 610 for the large-flowered and small-flowered types assuming 9 ovules/flower which indicates that this species is facultatively xenogamous. However the high proportion of inviable pollen in some plants, and the fact that their ovaries develop only a single ovule, will have a large bearing on the reproductive success of individual plants.
The lower anthers in C. roycei had more pollen grains than those in the upper whorl, though the difference between the two anther positions was less than for C. erythrochlorum. The proportion of apparently inviable grains in C. roycei was much lower than in C. erythrochlorum. The pollen/ovule ratio in C. roycei from Tutunup is about 540, assuming 8 ovules/flower which indicates facultative xenogamy. However, retention of self pollen on the stigma would seem to promote autogamy, or at least prevent cross pollen from reaching the stigma.
8
Rhind, Susan Gaye. "Ecology of the brush-tailed phascogale in jarrah forest of southwestern Australia." Thesis, Rhind, Susan Gaye (1998) Ecology of the brush-tailed phascogale in jarrah forest of southwestern Australia. PhD thesis, Murdoch University, 1998. https://researchrepository.murdoch.edu.au/id/eprint/52136/.
Abstract:
This study investigated the ecology of the marsupial brush-tailed phascogale (Phascogale tapoatafa; phascogale) in jarrah forest of Western Australia (WA). The thesis provides a descriptive account of the species' population dynamics, the phascogale’s size and growth, foraging ecology and nesting behaviour. The main work was undertaken between 1992-1995 and information was gathered by capture and by using radiotelemetry. The availability of food sources and refuge sites was examined and the species' immediate response to a logging operation was investigated. On a broader scale, the taxonomy of phascogales in WA was reviewed and their past and present distributions were explored by modelling and examination of museum records. The species has previously been subject to only one detailed study and this was undertaken in the State of Victoria.
Both similarities and differences were observed between the phascogales in WA and Victoria. Many of the differences appeared to have a nutritional basis. Phascogales are primarily arboreal insectivores and some of the invertebrates most commonly found in scats and stomachs were not abundant on trees. Nectarivory was very rarely observed (cf. Victoria). While phascogales are generalists in diet, they clearly show preferences for certain foods. The strongly seasonal climate in the southwest (long dry summers and wet winters) and the lack of diversity in tree species and low nectar availability probably limit food for WA phascogales. The dispersed nature of tree invertebrates and the apparent scarcity of some preferred prey, such as beetles, possibly explain the exclusive and often large size of female territories.
Phascogales in the study area were smaller and less sexually dimorphic than those in Victoria. Males were 30%, and females 20%, less in weight than those in Victoria. They were similarly smaller in skeletal size. Overall size was also found to vary' between habitat type and between years. In a year of drought phascogales did not achieve typical body size with mature males in that year weighing an average 25% less than usual. The evidence strongly suggests that annual and local availability of food is a major determinant of body size and growth.
Such variability in food availability may also be the evolutionary basis behind the litter sizes of WA phascogales. These are smaller than those in Victoria (mode WA = 6, Victoria = 8). The timing of major life-history events was as described for Victorian phascogales, although births occur a little later in the year. All males died at the end of the single annual breeding season (male semelparity) and young took some five to six months to raise to weaning. Some females survived to breed in a second year but the number encountered was low. The toll of lactation probably reduces lifespan and females were often in poor condition at late lactation and maximum maternal effort appears selectively invested in the first litter.
Typical of the semelparous species, females initially tried to raise as many young as they have teats. However, there was variation in litter sizes among females. The basis for this was anatomical as females had six, seven or eight teats. Such variation occurred throughout the study area, within litters and appears a State-wide phenomenon. Except in a hybrid Antechinus population, there appears to be no marsupial precedent for intrapopulation and intralitter variation in teat number. In such a strongly selected trait, it is speculated that such variation could only persist if the environment was spatially and/or temporally unstable in terms of food availability. There was no evidence that reduction in teat number was a direct trade-off that improved the chance of surviving to breed on a second occasion, but data were limited. The teat trait is presumably under genetic control and the promiscuous mating behaviour of phascogales may contribute, via multiple paternity, to the intralitter variability observed.
In the year of drought litters were significantly female biased. Neither sex were sexually dimorphic until they began foraging for themselves, therefore such bias was unlikely to reduce maternal stress during the drought conditions. The adaptive advantage of the bias was undetermined, but current literature indicates that such bias occurs at conception. However, female offspring probably have better post-weaning survival than males.
Examination of refuge requirements showed that natural nest sites were located in tree hollows. The profile of the trees chosen agree with most studies on hollow-nesting species. There was no apparent preference for particular tree species but there was a preference for nesting in older and senescent or dead trees. Females with dependent young showed particular preference for these trees' forms. However, once a tree was used, no tree characteristics measured were predictors of the tree being used on further occasions. Excluding females with young, phascogales typically spent 2-5 days nesting in the one refuge before moving to another. Females moved between alternative refuges more than males and home range maintenance is proposed to account for the difference (males were not territorial cf. females). For both sexes, parasite avoidance might account for the generally low level of nest-site fidelity. Individuals were estimated to use around 27 (males) and 38 (females) different nest-sites during one year of adult life. The parameters of hollows examined showed a preference for using hollows with small entrances. More than predator avoidance, interspecific competition for hollows may explain such selectivity.
Following the year of drought, communal nesting was common in autumn and winter. This was in marked contrast to data gathered early in the study and to the nesting behaviour of Victorian phascogales. Communal nesting was probably an energy conserving strategy adopted to compensate for unusually small body size. This behaviour may have been a single year event. However, as phascogales in the area are normally much smaller in body mass than those studied in eastern Australia, they may tend to nest communally in winter or when under conditions of hardship.
The immediate response of phascogales to logging was examined. Those affected continued to travel through and feed in the logged areas, which reinforces the concept of high site fidelity among animals. Phascogales were commonly found feeding among ground debris in cut areas indicating flexibility in foraging mode. With rare exceptions they ceased nesting in trees in the logged parts of their territories and confined such nesting to surrounding uncut forest. This suggests that the forestry practice of retaining a select number of hollow-bearing trees/ha may be insufficient to meet the species' refuge requirements in logged areas. Of concern is that currently unlogged sections in logged forest can be cut within 10-20 years yet trees take some 200 years to develop hollows. Additionally, the value of young regrovvth as a food source to this species is questionable. The study highlights the concerns that many scientists have regarding the preservation of hollow-nesting fauna in areas that are impacted by logging.
A revision of the species taxonomy (including the subspecies P. t. pirata) indicates that southern WA phascogales warrant subspecies status. Differences in basiacranial features were found between the regional groups in Australia. However, the issue of long-term geographic and reproductive isolation is perhaps the greater argument for suggesting subspecific status for WA phascogales. This is currently being examined using mitochondrial DNA techniques. This will provide not only a DNA profile of similarities and presumed differences between WA and southeastern phascogales, but will give an estimation of the time that the two groups have been separated.
A modelling exercise undertaken to examine the potential past distribution of WA phascogales showed that climatic conditions favourable to this species are found throughout the southern part of WA. For many of these areas there are no records of phascogales although a single historical work (1909) indicated that they were present in these areas. At that time they were apparently already extinct in some areas and dying out in others. A survey of the northern jarrah forest and a few other areas (by using nestboxes) failed to detect phascogales. The population examined during this study was therefore quite unusual in density, as phascogales were readily found in nestboxes. A myriad of factors culminating in low feral predation in the area seems the most likely explanation for the high densities observed. The conservation status of phascogales in areas other than the study region requires examination. Predation by exotic predators might account for the species' rarity, but food appears a generally limiting factor for phascogales and processes that alter habitat productivity may significantly impact this species.
9
Groom, Philip K. "Ecology and ecophysiology of southwestern Australian hakea species with contrasting leaf morphology and life forms." Thesis, Curtin University, 1996. http://hdl.handle.net/20.500.11937/2292.
Abstract:
Members of the genus Hakea (Proteaceae) are sclerophyllous, evergreen perennial shrubs or small trees endemic to Australia, with 65% of species confined to the South-West Botanical Province (southwestern Australia). Southwestern Australian Hakea species possess two contrasting leaf morphologies (broad or terete leaves) and fire-related life forms (non-sprouting (fire-killed) or resprouting (fire-surviving)), with each species representing one of four leaf morphology-life form groups.Representative species within each group were studied to determine whether they display similar distribution and ecophysiological patterns at both the adult and seedling stages. The distribution of species within these groups was best based on averages and variations in annual temperature and rainfall. The highest percentage of terete leaved non-sprouters (25 species) occurred in areas of low-moderate rainfall with large annual temperature ranges, whereas terete leaved resprouters (14 species) displayed a patchy distribution. Broad leaved resprouters (28 species) dominated areas of strongly seasonal rainfall, with few species occurring in the drier regions. Broad leaved non-sprouters (33 species) were best represented in areas of low annual temperature. The distribution of non-sprouters/resprouters may be due to the effect of climatic factors on seedling recruitment and/or fire frequencies. Leaf morphology appears to have a more direct influence on species distribution, as broad leaves are favoured in regions of medium-high, seasonal rainfall (less stressful habitats) while terete leaves are better adapted to tolerate hot, dry environments.Terete leaves are either simple (needle-like) or 2-3 pronged, and, apart from their narrow width, are characterised by their greater leaf thickness (> 1 mm), smaller projected area and mass, higher leaf mass per area (a measure of sclerophylly) and a lower density than broad leaves. Broad leaves are much more variable in their shape. Increased leaf thickness and sclerophylly in terete leaves can be partially attributed to the presence of a central parenchyma core and increased palisade thickness. This core is surrounded a compact network of fibre-capped vascular bundles. Thickness and sclerophylly were good indicators of relative nutrient content in terete, but not broad leaves. Both leaf types have a thick cuticle (> 20 mu m) and sunken stomates, with terete leaves possessing a greater stomatal density than broad leaves. Broad leaves are bilateral and hence amphistomatous. Adult and seedling leaves (of a similar leaf type) differed in morphology, but not anatomy, with some species producing broad seedling leaves and terete adult leaves.Seedlings growing under optimal growth conditions (full sunlight, well watered) in pots showed no relationship between rate of growth and ecophysiology with respect to the four species groupings, although seedlings of non-sprouters and broad leaved species had higher transpiration and photosynthetic rates than seedlings of resprouters and terete leaved species respectively. In response to high air temperatures (> 35°C), leaf temperatures close to or lower than the surrounding air temperature only occurred for terete leaved species possessing small individual and total leaf areas. By maintaining leaf photosynthesis rates during periods of relatively high air temperatures, terete leaved seedlings were able to produce more biomass per leaf area while retaining a low leaf area per seedling mass. When subjected to periods of water stress (withholding water), differences in water relations were most evident between seedlings of non-sprouters and resprouters, with resprouter seedlings showing an ability to minimise the decrease in relative water content for a given decrease in XPP. Although terete leaves possess many xeromorphic attributes, terete leaved seedlings were not necessarily superior at avoiding/tolerating drought. Terete leaves in seedlings may have alternative heat dissipation and/or anti-herbivore properties.Seasonal water relations of adult plants were monitored for over a year, including a period of prolonged summer drought at four sites (two on laterite (rocky substrate) and two on deep sand). The eight species inhabiting the lateritic sites were more stressed (more negative xylem pressure potentials (XPP)) in summer than the eight species on sandy soils, with lower conductances and higher leaf specific resistivity (XPP/area-based transpiration, LSR). Broad leaved species had higher transpiration rates and LSR, and more negative midday XPP throughout the study than terete leaved species. When spring (predrought) and summer (drought) data were compared, non-sprouters had lower XPP in summer, and lower transpiration rates and conductances in both seasons than resprouters. Non-sprouters on lateritic sites had the lowest water relations values in summer (drought tolerators). There was a tendency for broad leaved resprouters on sandy soils to have higher summer water relations values (drought avoiders). Broad leaved non-sprouters on lateritic soils could be considered the most water stressed group, with substantial plant death during the summer period. Terete leaved species on sandy soils were the most conservative in their water usage.
10
Luxton, Sarah Jayne. "Modelling refugia for improved conservation outcomes in the northern jarrah forest, southwestern Australia." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/84066.
11
Zosky, Kerry Louise. "Food resources and the decline of woylies Bettongia penicillata ogilbyi in southwestern Australia." Thesis, Zosky, Kerry Louise (2011) Food resources and the decline of woylies Bettongia penicillata ogilbyi in southwestern Australia. PhD thesis, Murdoch University, 2011. https://researchrepository.murdoch.edu.au/id/eprint/41707/.
Abstract:
Since 2001, woylie Bettongia penicillata ogilbyi populations in southwestern Australia have declined by at least 95%. The scale of this decline is larger and more rapid than that observed for the Tasmanian devil Sarcophilus harrisii, African elephant Loxodonta africana and lion Panthera leo. This rapid decrease in population size has prompted investigations to identify the putative causes of the decline. It is well established that changes in diet, food availability or foraging patterns can influence population trends, body condition and breeding and reproductive patterns, which in turn can lead to population declines. On the basis of this observation, the present study was designed to evaluate the dietary ecology of the woylie. Knowledge of the dietary ecology of the woylie is also important for conservation, recovery and ongoing management of existing populations. This study aimed to 1) quantify the diet of the woylie, by examining temporal and spatial variation of dietary components (primarily from faecal material), 2) investigate fungal food availability, the primary dietary component of the woylie and, 3) examine diet as a putative cause of recent population decline.
Faecal material collected between July 2006 and May 2007, from several populations within southwestern Australia was used to quantify the woylie’s diet. The results from the dietary analysis confirmed that woylies are predominantly mycophagous, with fungi (particularly sequestrate fungi) the major dietary component throughout the year at all study locations. Plant, invertebrate and seed material were also found but formed only minor components of the diet. Spatial variation in woylie diet was examined on two scales, regional level variation (southwestern Australia) and subregional variation (within the Upper Warren region). Very little spatial variation in the composition of dietary items was recorded between the subregional or regional study locations with the exception of Karakamia Wildlife Sanctuary, where significantly less fungi and more plant material were recorded. Seasonal variation was observed in the diet, whereby more fungi were consumed in winter and less fungi and more plant, fruits and invertebrates were consumed in the drier months of summer and spring. In addition, greater species richness and diversity of fungi were recorded in the diet during winter and spring compared to summer and autumn.
Sequestrate fungal sporocarp surveys were conducted in addition to the dietary analysis to investigate seasonal and spatial availability of fungi for woylies. Sequestrate sporocarp diversity and availability was shown to vary seasonally, but not spatially within the Upper Warren sites. During the winter months species richness and species diversity were high, sporocarps were more abundant and dry weight was higher. During spring, autumn and summer, sporocarps were less abundant and species richness and diversity were lower. Overall, when sporocarp availability was high (usually in winter) so too was the contribution of fungi in woylie faecal material and when sporocarp abundance was lower (spring and summer), woylies demonstrated a dietary shift and more plant, seed and invertebrate material were consumed. These results indicate a strong relationship between fungi availability and diet composition for the woylie.
When dietary trends were compared to demographic parameters which are often associated with population declines (e.g. body condition and reproductive success), it was found that the contribution of fungi in the diet was not related to woylie body condition, however it was a predictor for woylie reproductive success. Yet, reproductive success is unlikely to be associated with the recent decline of woylie populations as the overall proportion of females encountered with pouch young during the project was consistently high in both declining and declined populations and the proportions are consistent with results from earlier studies. The results from the dietary data comparing pre-decline diet (1999) with post decline diet (2006/7) did not reveal any significant association between decline and the amount of fungi within woylie diets. Furthermore, the decline status of the site showed no relationship to the amount of fungi in the diet. These results indicate that the dietary ecology of the woylie is not the primary causative agent of and is unlikely to have a significant role in the recent decline of woylie populations.
This study represented the first detailed investigation of woylie diet and, in conjunction with food availability data, provided important information on the dietary ecology of the woylie. While the results from this study indicate that diet and/or food resources are unlikely to be the cause of the recent decline in woylie populations, they form an important foundation to actively manage existing woylie populations, and also in the planning and establishment of populations in reintroduction programs.
12
Gaughan, Daniel J. "The diets and feeding ecology of larval fishes in Wilson Inlet, southwestern Australia." Thesis, Gaughan, Daniel J (1992) The diets and feeding ecology of larval fishes in Wilson Inlet, southwestern Australia. PhD thesis, Murdoch University, 1992. https://researchrepository.murdoch.edu.au/id/eprint/52015/.
Abstract:
Fish larvae and zooplankton were sampled at four sites in Wilson Inlet in twelve consecutive months. The annual mean concentration of fish larvae was less than one individual m^-3, whereas that of zooplankton was 447 000 individuals m^-3. The zooplankton assemblage was dominated by various life cycle stages of copepods (51.8% of the total catch), in particular their nauplii, and by tintinnid protozoans (29.8%). Copepod nauplii and Tintinnopsis sp. contributed 32.9 and 17.9 %., respectively, to the mean annual catch of zooplankton. The larvae of 10 species of fish were caught, of which six (Pseudogobius olorum, Afurcagobius suppositus, Favonigobius lateralis, Urocampus carinirostris, Parablennius tasmanianus and Engraulis australis) were common and four (Leptatherina presbyter aides, Atherinosoma elongata, Platycephalus speculator and Hyporhamphus melanochir) were rare. The guts of only the first five of the above six abundant species regularly contained food.
Overall, the relative composition of the diets of the larval fishes and the relative composition of the zooplankton were significantly (p < 0.01) correlated. The composition of the diets of P. olorum, F. lateralis, and P. tasmanianus were also usually positively correlated with the composition of the zooplankton, both on an overall basis and at individual sites within particular months. This did not apply, however, to A. suppositus and U. carinirostris. The nauplii, copepodites and adults of three species of copepods, namely Oithona simplex, Gladioferens imparipes and Acartia cf. simplex, contributed 76% of the total number, and 83% of the total volume, of prey eaten. Other important prey types were harpacticoids, bivalve larvae, polychaete larvae and the rotifer Synchaeta cf. baltica.
The assemblage of larval fishes within Wilson Inlet significantly (p < 0.05) selected only copepod nauplii in terms of numbers, and only O. simplex and G. imparipes with respect to volume. Copepod nauplii were usually positively selected only by P. tasmanianus and F. lateralis. In contrast, A. suppositus typically selected against copepod nauplii, but positively selected G. imparipes and harpacticoids. Pseudogobius olorum and U. carinirostris were the only species which often selected O. simplex, and the former also usually selected against copepod nauplii. Although relatively few prey types contributed to the diets of the fish larvae, the larvae of different species consumed different proportions of the available zooplankton, and this was reflected by the presence of significant dietary guild structure.
The larval fishes in Wilson Inlet consumed on average 0.33% of the standing crop of zooplankton in their region per day. This moderately low rate of consumption suggests that there was an excess of zooplanktonic food available for the fish larvae in Wilson Inlet and that they probably had little impact on the zooplankton populations. Despite the apparently abundant food supply, the larval fishes partitioned the food resources, which would minimize any potential for competition.
13
Tonk, Aafke M. "Longshore sediment transport driven by sea breezes on low-energy sandy beaches, Southwestern Australia." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/7644.
Abstract:
Longshore sediment transport rate was measured during energetic sea breeze activity, on intermediate-to-reflective sandy beaches in Southwestern Australia. Estimates of suspended load were obtained using backscatter sensors, current meters and streamer traps. Total load was determined using fluorescent tracer sand and an impoundment study. The measurementsw ere cross-compareda nd usedt o evaluates everalw idely-used longshore transport equations. The streamer trap measurement revealed an exponential distribution of the suspended sediment flux with vertical mixing decreasing in the onshore direction. A continuous time series of the longshore suspended sediment flux across the surf zone was obtained by combining the streamer trap measurements with data collected using surf zone instruments. Comparison of the suspended longshore flux with the total longshore flux derived from the dispersal of the sand tracer indicated that the relative contribution of the suspendedlo ad to the total load was at least 59 %. The movement of sandt racer on four different beaches demonstrated that nearshore sediments were transported obliquely across the surf zone, challenging our conventional view of dividing nearshore sediment transport into cross-shore and longshore components. Furthermore, tracer was found to move from the outer surf zone to the swash zone and vice versa, indicating a cross-shore sediment exchange. The contribution of the swash zone to the total longshore flux was estimated around 30-40 %. Despite large differences in the temporal and spatial scales of the measurement techniques, the littoral drift rates are comparable, suggesting a northward transport rate of 138,000-200,000 m3 year-1. Longshore sediment transport during sea breezes is mainly the result of a high longshore energy flux exerted by wind waves. This is accurately predicted by the equations of Inman and Bagnold (1963) and CERC (1984). The bimodal wave field, characteristic of Southwestern Australia, renders the Kamphuis (1991b) formula unsuitable in this instance.
14
Herath, Dulana Nilupul. "Fire impacts on restored shrublands following mining for heavy minerals near Eneabba, southwestern Australia." Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/556.
Abstract:
Following mineral-sand mining in the northern sandplains near Eneabba, southwestern Australia, rehabilitation managers have the difficult task of restoring shrubland communities of exceptional plant species richness. Management aims to restore a fully functional and self-sustaining shrubland community with similar vegetation and resilience properties to that of the surrounding natural vegetation. This thesis examines the performance of the restoration program by Iluka Resources Ltd. (and their predecessors) by comparing current vegetation properties and their response to fires on previously mined land versus the surrounding natural shrubland. As biomass accumulates post-restoration, fires will return as a natural disturbance factor and, as a result, a desirable measure of restoration success might include the ability of the postmined lands to recover from disturbance. Pre-burnt plant species diversity, composition, structure and key functional attributes in four mined sites rehabilitated 8 (R8) to 24 (R24) years ago were compared with those of surrounding natural areas classified on the basis of substrate type (low and high sand dunes, shallow sand swales, sand over laterite and sand over limestone). The rehabilitated sites (except R8) had more species (about 140) than natural sites (about 100) with 12–37% species in common with natural sites. Floristic composition was most similar to the local swales and dunes (physically closest).Two strong colonizers, the fire-killed Acacia blakelyi and the fire-tolerant Melaleuca leuropoma, were universally present. Plant densities were about a quarter to half those of natural sites. Fire-resprouters were under-represented. Growth-form distributions were most similar to those of the dunes, with some woody shrubs up to 2.5 m tall present. Greater iron levels and soil hardness (penetrability) were the only soil factors consistently greater in rehabilitated sites. Following experimental fires at the same study sites, species richness fell by 22–41% in rehabilitated sites but increased by 4–29% in natural sites. Species present before fire were reduced by 40–56% in rehabilitated sites and 4–12% in natural sites. Only 42–66% of resprouting species recovered in rehabilitated sites, whereas 96–100% recovered in natural sites. Nonsprouting species recruitment was also lower in rehabilitated (18–57%) than natural (67–85%) sites. Seedling mortality over the first summer after fire was higher in rehabilitated sites (59-86% death of individuals) than in natural sites (14-60%). PCoA ordination showed that fire altered the floristic composition of rehabilitated sites much more than it did in natural sites, mostly attributable to the loss of the extant resprouter species. It was found that the smaller lignotuber size (source of dormant buds) recorded in rehabilitated (vs. natural) resprouters was responsible for their higher post-fire mortality. For equivalent crown size in ten common lignotuberous shrub species, lignotuber circumferences were, on average, 50% smaller at rehabilitated sites.As a result, overall persistence in these species was much lower in rehabilitated (mean of 52% alive, range of 11–93%) versus natural sites (mean of 96%, range of 79–100%), but improved with time since restoration for five of the ten selected species. Apart from differences in the age of the plants (natural sites having much older plants recruited after previous fires), the lower soil penetrability at rehabilitated sites may have restricted lignotuber development. A tradeoff favoring a higher crown volume to lignotuber size ratio was also apparent in nine of the ten species with greater crown volumes (by 37%) and smaller lignotubers (by 36%) in rehabilitated sites. Demographic attributes for six selected woody species were compared between rehabilitated and natural sites (~3-30 years since disturbance) to investigate growth patterns and optimum fire-return intervals. At matched years since restoration or last fire, nonsprouter species in rehabilitated sites grew larger (1.1 to 4.7 times) and produced/stored more viable seeds per plant (1.1 to 10.9 times). Despite older aged individuals in natural sites at matched years since restoration vs. last fire, restored resprouters were larger (1.1 to 3.6 times) and produced/stored more viable seeds (1.1 to 6.9 times). Although greater growth and fecundity rates were recorded in rehabilitated sites, the estimated optimum fire-return interval based on maximum seed production was similar in rehabilitated and natural sites for five out of six species.However, mean fire intervals typical of surrounding natural vegetation near the Eneabba area (13 years over the last 40 years) may not be suitable for rehabilitated minesites at Eneabba, whereby longer initial fire intervals (20–30 years) would better ensure persistence of resprouter individuals via the seedling recruitment strategy and resprouting strategy. Iv My study indicated that the returned vegetation can at present be classified as “rehabilitated” or “partially restored” but not “completely restored” since the original plant diversity, composition, structure, and resilience properties to fire have not yet been achieved. It may not be possible/realistic to achieve complete restoration since mining is such a destructive disturbance type that some complex ecological attributes may take centuries to develop. I discuss six key factors as important in improving the overall restoration success at Eneabba: 1) restoration of a deeper topsoil and looser subsoil profile; 2) collection of appropriate amounts of only local provenance species, mulch and topsoil; 3) control of highly competitive species; 4) management of fertilizer additions; 5) reseeding and replanting in subsequent years after the initial restoration treatments, including after initial fires; and 6) delaying the introduction of management fires until the restored vegetation develops sufficient fire-resilience properties.
15
Herath, Dulana Nilupul. "Fire impacts on restored shrublands following mining for heavy minerals near Eneabba, southwestern Australia." Curtin University of Technology, Department of Environmental Biology, 2008. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=116352.
Abstract:
Following mineral-sand mining in the northern sandplains near Eneabba, southwestern Australia, rehabilitation managers have the difficult task of restoring shrubland communities of exceptional plant species richness. Management aims to restore a fully functional and self-sustaining shrubland community with similar vegetation and resilience properties to that of the surrounding natural vegetation. This thesis examines the performance of the restoration program by Iluka Resources Ltd. (and their predecessors) by comparing current vegetation properties and their response to fires on previously mined land versus the surrounding natural shrubland. As biomass accumulates post-restoration, fires will return as a natural disturbance factor and, as a result, a desirable measure of restoration success might include the ability of the postmined lands to recover from disturbance. Pre-burnt plant species diversity, composition, structure and key functional attributes in four mined sites rehabilitated 8 (R8) to 24 (R24) years ago were compared with those of surrounding natural areas classified on the basis of substrate type (low and high sand dunes, shallow sand swales, sand over laterite and sand over limestone). The rehabilitated sites (except R8) had more species (about 140) than natural sites (about 100) with 12–37% species in common with natural sites. Floristic composition was most similar to the local swales and dunes (physically closest).Two strong colonizers, the fire-killed Acacia blakelyi and the fire-tolerant Melaleuca leuropoma, were universally present. Plant densities were about a quarter to half those of natural sites. Fire-resprouters were under-represented. Growth-form distributions were most similar to those of the dunes, with some woody shrubs up to 2.5 m tall present. Greater iron levels and soil hardness (penetrability) were the only soil factors consistently greater in rehabilitated sites. Following experimental fires at the same study sites, species richness fell by 22–41% in rehabilitated sites but increased by 4–29% in natural sites. Species present before fire were reduced by 40–56% in rehabilitated sites and 4–12% in natural sites. Only 42–66% of resprouting species recovered in rehabilitated sites, whereas 96–100% recovered in natural sites. Nonsprouting species recruitment was also lower in rehabilitated (18–57%) than natural (67–85%) sites. Seedling mortality over the first summer after fire was higher in rehabilitated sites (59-86% death of individuals) than in natural sites (14-60%). PCoA ordination showed that fire altered the floristic composition of rehabilitated sites much more than it did in natural sites, mostly attributable to the loss of the extant resprouter species. It was found that the smaller lignotuber size (source of dormant buds) recorded in rehabilitated (vs. natural) resprouters was responsible for their higher post-fire mortality. For equivalent crown size in ten common lignotuberous shrub species, lignotuber circumferences were, on average, 50% smaller at rehabilitated sites.
As a result, overall persistence in these species was much lower in rehabilitated (mean of 52% alive, range of 11–93%) versus natural sites (mean of 96%, range of 79–100%), but improved with time since restoration for five of the ten selected species. Apart from differences in the age of the plants (natural sites having much older plants recruited after previous fires), the lower soil penetrability at rehabilitated sites may have restricted lignotuber development. A tradeoff favoring a higher crown volume to lignotuber size ratio was also apparent in nine of the ten species with greater crown volumes (by 37%) and smaller lignotubers (by 36%) in rehabilitated sites. Demographic attributes for six selected woody species were compared between rehabilitated and natural sites (~3-30 years since disturbance) to investigate growth patterns and optimum fire-return intervals. At matched years since restoration or last fire, nonsprouter species in rehabilitated sites grew larger (1.1 to 4.7 times) and produced/stored more viable seeds per plant (1.1 to 10.9 times). Despite older aged individuals in natural sites at matched years since restoration vs. last fire, restored resprouters were larger (1.1 to 3.6 times) and produced/stored more viable seeds (1.1 to 6.9 times). Although greater growth and fecundity rates were recorded in rehabilitated sites, the estimated optimum fire-return interval based on maximum seed production was similar in rehabilitated and natural sites for five out of six species.
However, mean fire intervals typical of surrounding natural vegetation near the Eneabba area (13 years over the last 40 years) may not be suitable for rehabilitated minesites at Eneabba, whereby longer initial fire intervals (20–30 years) would better ensure persistence of resprouter individuals via the seedling recruitment strategy and resprouting strategy. Iv My study indicated that the returned vegetation can at present be classified as “rehabilitated” or “partially restored” but not “completely restored” since the original plant diversity, composition, structure, and resilience properties to fire have not yet been achieved. It may not be possible/realistic to achieve complete restoration since mining is such a destructive disturbance type that some complex ecological attributes may take centuries to develop. I discuss six key factors as important in improving the overall restoration success at Eneabba: 1) restoration of a deeper topsoil and looser subsoil profile; 2) collection of appropriate amounts of only local provenance species, mulch and topsoil; 3) control of highly competitive species; 4) management of fertilizer additions; 5) reseeding and replanting in subsequent years after the initial restoration treatments, including after initial fires; and 6) delaying the introduction of management fires until the restored vegetation develops sufficient fire-resilience properties.
16
Semeniuk, Christine. "Evolution of wetland habitats and vegetation associations on a holocene coastal plain, Southwestern Australia." Thesis, Semeniuk, Christine (2002) Evolution of wetland habitats and vegetation associations on a holocene coastal plain, Southwestern Australia. PhD thesis, Murdoch University, 2002. https://researchrepository.murdoch.edu.au/id/eprint/51816/.
Abstract:
This study takes a multi-disciplinary approach to the investigation of a genetically related suite of wetlands, the Becher Suite, on the Swan Coastal Plain in southwestern Australia. The wetlands occur on a vegetated beachridge plain which forms the surface of an accretionary cuspate foreland, the Becher Cuspate Foreland. The Becher Cuspate Foreland is the largest sedimentary coastal deposit on the southwestern Australian coast which, by nature of its formation, contains a 7,000 year Holocene history of sea level changes, shoreline and beachridge plain development, and climate history. When swales within the beachridge plain became waterlogged or inundated by a rising water table following coastal progradation and a gradually falling sea level, it signalled the commencement of wetland development. Because of the varying geographic relationship between the ground surface and the water table, wetland initiation across the beachridge plain was staggered, commencing circa 4,500 years BP and continuing to circa 600 years BP.
Wetland basins were filled with carbonate mud and peat, and over time, sedimentologic, pedogenic, diagenetic and hydrological processes created stratified wetland sedimentary sequences. An increase in the heterogeneity of wetland fill in response to regional climatic processes progressively influenced hydrological functions in and adjacent to wetland basins. The combined effects of a local and variable wetland stratigraphy and plant uptake and release on cation concentrations down profile in sediments, interstitial waters and groundwater, resulted in very localised hydrochemical signatures specific to the type of sedimentary fills, their evolutionary stage, and to their extant vegetation association. The Becher Suite wetlands demonstrate that less than a metre of wetland sediment not only sets the wetland apart from larger scale regional processes, but establishes a physical, chemical and biological system which evolves independently.
Vegetation across the range of wetlands in the study area exhibits an increase in complexity of pattern and form with increased age of wetland. In the youngest wetlands, the vegetation is uniform sedgeland. With increasing age, the pattern becomes concentrically zoned with two, three and four zones, comprising mixed sedgeland, herbland, shrubland, or low forest, and an outer zone of closed grass tree. The fluctuations in plant communities recorded over 10 years, as well as that recorded geohistorically in the pollen record indicate expansion and contraction of vegetation assemblages in response to fluctuating hydrological conditions within the wetland basins, and in the long term, in response to some climate forcing.
17
Judd, Simon L. "Terrestrial isopods (Crustacea: Oniscidea) and biogeographical patterns from South-Western Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2004. https://ro.ecu.edu.au/theses/1613.
Abstract:
This thesis examines terrestrial isopod (Crustacea: Oniscidea) diversity and biogeography from south-western Australia, a region already recognised for the exceptional high biodiversity and concentrations of endemic species. A taxonomic investigation of isopods in the Western Australian Museum and material collected systematically as part of this study revealed seventy taxa, sixty of which were considered native species. The thesis provides a comprehensive review of regional taxonomic history and includes a key, complete with a set of forty characters states and taxa, illustrated by a number of photographic plates that are designed for use by specialists and non-specialists alike. Prior to this study all the region's indigenous terrestrial isopods were poorly described and, while many taxa are still to be resolved at the species level, it appears at least 35 species are new to science. The distributions of indigenous taxa form some clear and consistent biogeographical patterns. Distributions of taxa are influenced by steep rainfall gradients, the seasonality of rainfall and by biophysical characteristics of the landscape including, localised landforms and differing microhabitat utilisation. The region is one of high diversity, with both widely distributed species and highly localised endemics. Two areas, the Perth region of the Swan Coastal Plain and the tall, wet southern forests, are particularly species rich. Beta diversity is also high. This reflects a heterogeneous landscape with profound differences in microhabitat availability, differences often due to recent exogenous disturbance. The construction of a biogeographic model showed a major fauna/ break, which created northern and southern bioregions to which 68% of the taxa were endemic. This biogeographical boundary is significant in that it had not been recognised in any previous biogeographical schemes. Data derived from the analysis of soil, leaf litter and log microhabitat samples show that the existence of terrestrial isopods in south-western Australia is intractably related to organic matter. The geographical range of species is often best explained by the types of microhabitat utilised and their degree of moisture dependency. The wetter forests of the region contain relictual short range endemics reliant upon surface organic matter, particularly leaf litter. Moisture is clearly a limiting factor in the distribution of all species. The five most common genera can be differentiated by their dependence upon different moisture regimes in a range of microhabitat types. The spatial and temporal continuity of different types of organic matter in forested landscapes is considered critical to the conservation of the group in south-Western Australia. Land management practices, such as logging and burning, which influence the nature and distribution of organic matter, are likely to induce profound changes in terrestrial isopod communities. Regular and broadscale prescription burning and the increasing scarcity of large and decayed logs are considered to be a primary threat to their conservation status. Hypotheses involving the historical role of surface organic matter are developed to explain the speciation patterns of the group in the region. In order to test these models, and to provide an urgently needed assessment of the conservation status of relictual forest invertebrates, clear taxonomic priorities are recommended.
18
Williams, Aleida Helen. "An ecophysiological comparison of rare ironstone endemics and their common congeners." University of Western Australia. School of Plant Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0241.
Abstract:
[Truncated abstract] In south-western Australia a rare plant community occurs on shallow soils overlaying massive ironstone rock. These 'ironstone communities' are open shrublands, which are subject to extremes in drought and solar radiation and support many rare and endemic species. The restricted distribution of many of these species may be related to their high degree of specialisation to this harsh habitat and their inability to respond plastically to different environmental conditions. Indeed, earlier work has shown that ironstone Hakea species (Proteaceae) have a specialist root-system morphology investing mainly in deep roots, thereby increasing their chance of accessing cracks in the rock surface and obtaining water before the onset of summer drought. In this thesis I further examine aspects of specialisation and its possible consequences for species rarity using two ironstone Hakea species and comparing them with two of their widely distributed congeners. In the first experiment (Chapter 2) I explore inherent drought tolerance, independent of root-system morphology, as a further specialisation to the ironstone environment. All species were grown in sand in pots in a glasshouse for 7 months and then droughted for 5 weeks. There was no evidence that the ironstone species had a greater inherent drought tolerance than their common congeners. During drought all species maintained leaf water content of mature leaves by reducing stomatal conductance and osmotically adjusting, though ironstone species tended to OA (osmotic adjustment) more than common species. ... This suboptimal investment of resources may result in a lower competitive ability in shadier environments, and thus could partially explain their restricted distribution. In Chapter 4, I investigated the plasticity of root traits in response to levels of phosphorus supply. South-western Australian soils are phosphorus impoverished and phosphorus is well known to elicit plastic responses in root allocation and architecture. Ironstone species showed less plasticity in total root length, producing similar root length across P treatments, while common species showed an increase in root length with increasing [P]. Other root characteristics were similarly plastic in response to P treatment between species. However, when supplied with increasing [P], ironstone species invested an increasing proportion of roots in the bottom of pots while common species invested more in the top. This differential response in root allocation in response to P may reflect a fundamental trade-off between nutrient and water acquisition, with the ironstone species mainly foraging for water and investing in deeper roots, while the common species invest more in superficial roots to obtain nutrients. In conclusion, the rarity and restricted distribution of the ironstone Hakea species may be related to their specialist root-system morphology as well as a lowered phenotypic plasticity of functional traits. A reduction in plasticity may reduce their competitive ability outside their ironstone habitats, and thus contribute to the restricted distribution of these species. This may also be the case for other rock-outcrop endemics and more generally, for other rare plant species restricted to particular habitats where a lowered phenotypic plasticity in traits relevant to their particular habitat may contribute to their restricted distribution.
19
Itzstein-Davey, Freea. "Changes in the abundance and diversity of the Proteaceae over the Cainozoic in south-western Australia." University of Western Australia. School of Earth and Geographical Sciences, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0040.
Abstract:
South-western Australia is a globally significant hotspot of plant species diversity, with high endemism and many rare plant species. Proteaceae is a major component of the south-western flora, though little is known about how its diversity developed. This prompted the present study to investigate changes in the abundance and diversity of Proteaceae, in south-western Australia, by concurrently studying three sediment sequences of different ages over the Cainozoic and a modern pollen rain study. Modern pollen-vegetation relationships in the two Proteaceae species rich nodes of the northern and southern sandplains were quantified. It was found that Proteaceous genera can contribute up to 50% of the total pollen rain. Banksia/Dryandra pollen was the most abundant with Isopogon, Petrophile and Lambertia also commonly noted. The vegetation and environmental setting during three pivotal periods of the Cainozoic: Holocene, Pliocene and Eocene, were investigated. Eocene sediment from Lake Lefroy confirmed the presence of a Nothofagus dominated rainforest in the Middle to Late Eocene. At this time Proteaceae species were at least as diverse as today, if not more so, contributing up to a maximum of 42% of the total pollen rain. Taxa recorded included: Banksieaeidites arcuatus, Propylipollis biporus, Proteacidites confragosus, Proteacidites crassus, Proteacidites nasus and Proteacidites pachypolus. Several taxa remain undescribed and unnamed. This study also identified that Proteaceae pollen representation varies across small lateral distances. Thus as samples varied spatially and temporally, single core samples are not sufficient to identify spatial patterns in Proteaceae or other low pollen producing taxa. Some 7.91 cm of laminated Pliocene sediment from Yallalie, south-western Australia, was also examined. It covers 84 years of record and confirmed other regional reports that south-western Australia was covered by a rich vegetation mosaic consisting of heathy and wet rainforest elements. Although Proteaceae species were a consistent component of the pollen counts, diversity and abundance (maximum of 5%) was low throughout the studied section. Banksia/Dryandra types were most commonly noted. A 2 m core was retrieved from Two Mile Lake, near the Stirling Ranges and provided an early Holocene vegetation history. Geochemical and palynological evidence recorded little change, suggesting the environment of deposition was relatively uniform. Proteaceae species were noted throughout the core, though in low numbers, at a maximum of 3.5 % of the total pollen rain. Banksia/Dryandra was the most abundant while Isopogon, Lambertia, Petrophile and Franklandia were also noted. A regression model was developed through the modern pollen rain study to predict the number of Proteaceae in the vegetation. This was also applied to the fossil pollen records. The estimated number of Proteaceae species in the Eocene suggests a maximum of 20 and a minimum of 10 taxa. For the Pliocene record, an estimated 7 - 9 species was found and for the Holocene pollen, between 7 - 8 were present. Thus the Eocene was similar in Proteaceae diversity to today. The results from the Pliocene and Holocene suggest that Proteaceae diversity was lower than today. Findings of this research indicate that Proteaceae species are an important and consistent component of vegetation in south-western Australia over the Cainozoic. It is likely that both changing pollination mechanisms and changes in associated vegetation are important in the determining the dispersal of Proteaceaous pollen. By understanding how the vegetation has changed and developed in south-western Australia, present vegetation can be managed to include intra-specific variation and ensure the majority of species are conserved for present and future generations to enjoy.
20
Groom, Philip K. "Ecology and ecophysiology of southwestern Australian hakea species with contrasting leaf morphology and life forms." Curtin University of Technology, School of Environmental Biology, 1996. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=12057.
Abstract:
Members of the genus Hakea (Proteaceae) are sclerophyllous, evergreen perennial shrubs or small trees endemic to Australia, with 65% of species confined to the South-West Botanical Province (southwestern Australia). Southwestern Australian Hakea species possess two contrasting leaf morphologies (broad or terete leaves) and fire-related life forms (non-sprouting (fire-killed) or resprouting (fire-surviving)), with each species representing one of four leaf morphology-life form groups.Representative species within each group were studied to determine whether they display similar distribution and ecophysiological patterns at both the adult and seedling stages. The distribution of species within these groups was best based on averages and variations in annual temperature and rainfall. The highest percentage of terete leaved non-sprouters (25 species) occurred in areas of low-moderate rainfall with large annual temperature ranges, whereas terete leaved resprouters (14 species) displayed a patchy distribution. Broad leaved resprouters (28 species) dominated areas of strongly seasonal rainfall, with few species occurring in the drier regions. Broad leaved non-sprouters (33 species) were best represented in areas of low annual temperature. The distribution of non-sprouters/resprouters may be due to the effect of climatic factors on seedling recruitment and/or fire frequencies. Leaf morphology appears to have a more direct influence on species distribution, as broad leaves are favoured in regions of medium-high, seasonal rainfall (less stressful habitats) while terete leaves are better adapted to tolerate hot, dry environments.Terete leaves are either simple (needle-like) or 2-3 pronged, and, apart from their narrow width, are characterised by their greater leaf thickness (> 1 mm), smaller projected area and mass, higher leaf mass per area (a measure of sclerophylly) and a ++lower density than broad leaves. Broad leaves are much more variable in their shape. Increased leaf thickness and sclerophylly in terete leaves can be partially attributed to the presence of a central parenchyma core and increased palisade thickness. This core is surrounded a compact network of fibre-capped vascular bundles. Thickness and sclerophylly were good indicators of relative nutrient content in terete, but not broad leaves. Both leaf types have a thick cuticle (> 20 mu m) and sunken stomates, with terete leaves possessing a greater stomatal density than broad leaves. Broad leaves are bilateral and hence amphistomatous. Adult and seedling leaves (of a similar leaf type) differed in morphology, but not anatomy, with some species producing broad seedling leaves and terete adult leaves.Seedlings growing under optimal growth conditions (full sunlight, well watered) in pots showed no relationship between rate of growth and ecophysiology with respect to the four species groupings, although seedlings of non-sprouters and broad leaved species had higher transpiration and photosynthetic rates than seedlings of resprouters and terete leaved species respectively. In response to high air temperatures (> 35°C), leaf temperatures close to or lower than the surrounding air temperature only occurred for terete leaved species possessing small individual and total leaf areas. By maintaining leaf photosynthesis rates during periods of relatively high air temperatures, terete leaved seedlings were able to produce more biomass per leaf area while retaining a low leaf area per seedling mass. When subjected to periods of water stress (withholding water), differences in water relations were most evident between seedlings of non-sprouters and resprouters, with resprouter seedlings showing an ability to minimise the decrease in relative water content for a given decrease in XPP. ++
Although terete leaves possess many xeromorphic attributes, terete leaved seedlings were not necessarily superior at avoiding/tolerating drought. Terete leaves in seedlings may have alternative heat dissipation and/or anti-herbivore properties.Seasonal water relations of adult plants were monitored for over a year, including a period of prolonged summer drought at four sites (two on laterite (rocky substrate) and two on deep sand). The eight species inhabiting the lateritic sites were more stressed (more negative xylem pressure potentials (XPP)) in summer than the eight species on sandy soils, with lower conductances and higher leaf specific resistivity (XPP/area-based transpiration, LSR). Broad leaved species had higher transpiration rates and LSR, and more negative midday XPP throughout the study than terete leaved species. When spring (predrought) and summer (drought) data were compared, non-sprouters had lower XPP in summer, and lower transpiration rates and conductances in both seasons than resprouters. Non-sprouters on lateritic sites had the lowest water relations values in summer (drought tolerators). There was a tendency for broad leaved resprouters on sandy soils to have higher summer water relations values (drought avoiders). Broad leaved non-sprouters on lateritic soils could be considered the most water stressed group, with substantial plant death during the summer period. Terete leaved species on sandy soils were the most conservative in their water usage.
21
Rossi, Alana. "An archaeological re-investigation of the Mulka's Cave Aboriginal rock art site, near Hyden, Southwestern Australia." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2010. https://ro.ecu.edu.au/theses/1884.
Abstract:
Mulka's Cave is a profusely decorated hollow boulder at The Humps, a large granite dome near Hyden, a small town 350 km southeast of Perth. The importance of the artwork has been recognised for 50 years. Test excavations in the cave in 1988 yielded 210 mainly quartz artefacts assignable to the Australian Small Tool phase and a radiocarbon date of 420 ± 50 BP from just below the lowest artefact found. The artwork was recorded in detail in 2004. The recorder considered the radiocarbon date to be 'anomalously young' because most of the artwork is in poor condition, suggesting that it was made 3000-2000 years ago. Other dated rock art sites in Southwestern Australia came into use 4000-3000 BP. The excavators argued that the site was fairly insignificant, while the rock art researcher thought the profusion of motifs (452) made it a site of some significance, particularly in Southwestern Australia. The main aim of this study was to investigate these conflicting claims by re-investigating how Mulka's Cave had been used by Aboriginal people in the archaeological past.
This research became possible because local tourist organisations obtained federal funding to install an elevated walkway outside the cave in 2006. Under Section 18 of the Aboriginal Heritage Act (1972) 12 of the 34 postholes required were excavated and artefacts were collected from all the ground surfaces to be impacted. Subsequently, under Section 16 of the AHA, four, small, 0.5 x 0.5 m, testpits were excavated around the site: outside the cave entrance, on The Humps and in the Camping Area; a sheltered spot where the Traditional Owners had camped as children, with their grandparents. Organic material was scarce, so analysis focused on the numbers and types of stone artefacts recovered. The artefacts excavated in 1988 were also re-analysed. Five radiocarbon dates were obtained, which suggested that people began visiting the Camping Area (and using ochre) about 6500 BP, making Mulka's Cave one of the oldest radiometrically dated rock art sites in southern Western Australia.
The artefact data from Mulka's Cave were compared to those from these sites. The low artefact discard rate and high proportion of retouched/formal tools found at Mulka's Cave may indicate that the site was used differently from the other sites, but the data are problematic. Most (70%) of the handstencils in Mulka's Cave can be attributed to adolescents, possibly boys, which may also suggest that the site had ceremonial significance; perhaps as a focus for male initiation rituals. The artefact data do not support this hypothesis, however. There is no evidence of spatial patterning in artefact type or frequency across the site, which would be expected if the cave had had a ritual function. Instead, the Camping Area, Walkway Area and Mulka's Cave itself seem to have been used similarly.
It was concluded that, given the scarcity of free-standing potable water in the surrounding region and the presence at The Humps of two capacious gnammas (rockholes), that people probably visited the site when the gnammas were full. A wide variety of plant and animal foods would also have been available before the country was cleared for agriculture. When at Mulka's Cave, they may well have added to the corpus of rock art and carried out other ceremonial business, but there is no archaeological evidence for the latter.
It was also concluded that much more research needs to be undertaken in this neglected part of the semi-arid zone before the significance of Mulka's Cave can be properly assessed and its place in the archaeological record of Southwestern Australia determined.
22
au, kdsmith@fish wa gov, and Kimberley Dale Smith. "Distributions, relative abundances and reproductive biology of the deep-water crabs Hypothalassia acerba and Chaceon bicolor in southwestern Australia." Murdoch University, 2006. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20061129.142618.
Abstract:
Three species of large crab are found in Western Australian waters, namely the champagne crab Hypothalassia acerba, the crystal crab Chaceon bicolor and the giant crab Pseudocarcinus gigas, all of which are fished commercially in these waters. This thesis reports the results of studies carried out on the biology of the first two species, for which there were previously very little information. The results increase our knowledge of the benthic fauna in deeper waters off the southwestern Australian coast and provide data that can be used by fisheries managers to develop plans for conserving the stocks of H. acerba and C. bicolor.
The champagne crab Hypothalassia acerba is found southwards of Kalbarri at ~ 27aS, 114aE on the west coast and eastwards to Eucla at ~ 32aS, 129aE on the south coast. There is a small commercial trap fishery for H. acerba on both the lower west and south coasts of Western Australia. However, on the west coast, H. acerba is managed as a single species fishery, whereas on the south coast it is a component of a multi-species fishery, which also includes the southern rock lobster Jasus edwardsii and P. gigas. On the west coast, the commercial catches of H. acerba increased sharply from ~ 1,500 kg in 1989 to reach maximum levels of 30-46,000 kg in 1997-99, reflecting a marked increase in fishing effort. However, it subsequently declined to essentially zero after 2000 due to effort shifting towards fishing for C. bicolor. Catches of H. acerba on the south coast peaked at 26-27,000 kg in 1997-98 but, in contrast to those on the west coast, remained relatively high in 2001 to 2003.
The crystal crab Chaceon bicolor occurs in water depths of ~ 450 to 1220 m around Australia and New Zealand. However the commercial fishery is almost entirely located between Carnarvon on the north-west coast at ~ 25aS, 113aE to approximately Windy Harbor at ~ 35aS, 116aE on the south coast. Commercial catches of C. bicolor in southwestern Australia, which came almost entirely from the lower west coast, rose from very low levels in 1997 to ~ 222,000 kg in 2001 and then remained close to this level in 2002 and 2003. These trends largely reflect an increase in fishing effort.
Hypothalassia acerba was sampled seasonally by setting traps at depths of 35, 90, 145, 200, 255, 310 and 365 m on the west and south coasts of Western Australia. Catch rates on the west and south coasts peaked sharply at depths of 200 and 145 m, respectively, but at similar temperatures of 16 - 17¢XC. The catches on those coasts contained 69 and 84% males, respectively. The carapace length of H. acerba declined significantly by 4 mm for each 100 m increase in depth. Males attained a greater maximum carapace length than females on both the west coast, i.e. 135 vs 113 mm, and south coast, i.e. 138 vs 120 mm. Furthermore, after adjustment to a common depth of 200 m, the mean carapace length of males was greater than females on both the west coast (96.6 vs 94.6 mm) and south coast (101.5 and 91.4 mm) and the latter difference was significant (p < 0.001). These results thus show that, for H. acerba, (1) the distribution is related to depth and temperature, (2) body size is inversely related to water depth and (3) males grow to a larger size and are more prevalent in catches than females. There was also evidence that the distribution of H. acerba changed slightly with season and that there was spatial partitioning by this species and other large deep water invertebrate predators.
The trends exhibited by reproductive variables demonstrate that H. acerba reproduces seasonally on the lower west coast, with ovaries maturing progressively between July and December and oviposition occurring between January and March. The characteristics of H. acerba on the south coast differed in the following ways from those on the lower west coast. (i) No ovigerous females and only two females with egg remnants were caught. (ii) Ovaries did not develop late yolk granule oocytes until females had reached a larger size. (iii) Investment in gonadal development was less. These results strongly suggest that conditions on the south coast are not as conducive for ovarian development and reproduction and indicate that females migrate from the south to lower west coast for spawning. In contrast to H. acerba, C. bicolor reproduces throughout much or all of the year on the lower west coast, presumably reflecting its occupancy of far deeper waters where environmental conditions vary less during the year. Although the mean weights of ovigerous females of H. acerba and C. bicolor were not significantly different (p > 0.05), the mean fecundity of the former species (356,210) was significantly greater (p < 0.001) than that of the latter species (192,070). The relatively high fecundity of H. acerba may reflect adaptations by this species to optimise egg production during its relatively short breeding season.
The size at onset of sexual maturity (SOM) of the females of crustacean species, which is often used by fisheries managers for developing management plans for such species, is typically estimated using logistic regression analysis of the proportions of mature females in sequential size classes. The validity of this approach depends on the composition of the samples reflecting accurately that present in the environment. However, catches obtained by traps, a passive fishing method, typically contain disproportionately greater numbers of large crabs, whereas those obtained using active fishing methods, such as seine netting and otter trawling, will presumably represent far better the size composition of the population. Since H. acerba and C. bicolor could be caught in numbers only by using traps, comparisons between the influence of passive and active fishing methods were explored using the extensive data previously collected for Portunus pelagicus employing different sampling methods (de Lestang et al. 2003a,b). These data are analysed in order to demonstrate that the females of P. pelagicus caught by trapping were predominantly mature, whereas those obtained by seining and trawling contained numerous immature as well as mature females. The samples of females collected by trap are, therefore, clearly biased towards mature crabs. Consequently, for any size class, it would be predicted that the proportion of mature females in trap catches will be overestimated, thus shifting the logistic curve fitted to the proportions of mature crabs at each size to the left, and thereby yielding an underestimate of the SOM. This conclusion is substantiated by the fact that the carapace width of female P. pelagicus, at which 50% of individuals reach maturity (SOM50), was estimated to be markedly greater when using the proportion of mature females obtained by seine-netting and otter trawling collectively, i.e. 101.1 mm, than by trapping, i.e. 86.1 mm. From the above data for P. pelagicus, it is considered likely that, through a greater vulnerability of mature females of these species to capture by traps, the respective SOM50s derived for female H. acerba and C. bicolor from trap samples (i.e. carapace lengths of 69.7 and 90.5 mm) will represent considerable underestimates of the true SOM50s.
Many workers have assumed that the chelae of male crabs undergo a change in allometry at the pubertal moult and that this could thus be used as the basis for determining the size of those crabs at morphometric maturity. Since initial plots of the logarithms of propodus length and carapace width (CW) of the males of P. pelagicus and carapace length (CL) of the males of H. acerba and C. bicolor revealed no conspicuous change in allometry, the question of whether the chelae of these species undergo such an allometric change was explored statistically. The Akaike and Bayesian Information Criteria were thus used to ascertain whether a linear, quadratic, broken stick or overlapping-lines model best represented the above logarithmic size data. Since the broken stick model provided the best fit for P. pelagicus, the chelae of this species does undergo allometric change. This occurred at 80.0 mm CW, which is ~ 8 mm less than the CW at physiological maturity. In contrast, my analyses provided no evidence that the chelae of either H. acerba or C. bicolor exhibited an inflection and thus morphometric maturity could not be determined for these two species from chela length. Thus, mangers will have to use the SOM50 for physiological maturity, which was estimated to be 68.1 and 94.3 mm CL for H. acerba and C. bicolor, respectively.
23
Smith, Brett. "The late quaternary history of Southern hemisphere mediterranean climate regions in the Western Cape, South Africa, and Southwestern Australia." Doctoral thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/12162.
Abstract:
Includes abstract.Includes bibliographical references (leaves 215-241).
The study is focused on four study sites, two in the Western Cape, namely the Bruno section and Lake Michelle and two in southwestern Australia, namely Wambellup Swamp and Devil's Pool. These sites were chosen as they are well situated to investigate the complex interaction between Late Quaternary climate change, the influence of fluctuating sea levels and the impact of human interaction with the environments in question and provide a regional picture of these interactions.
24
Smith, Kimberley Dale. "Distributions, relative abundances and reproductive biology of the deep-water crabs Hypothalassia acerba and Chaceon bicolor in southwestern Australia." Thesis, Smith, Kimberley Dale (2006) Distributions, relative abundances and reproductive biology of the deep-water crabs Hypothalassia acerba and Chaceon bicolor in southwestern Australia. PhD thesis, Murdoch University, 2006. https://researchrepository.murdoch.edu.au/id/eprint/318/.
Abstract:
Three species of large crab are found in Western Australian waters, namely the champagne crab Hypothalassia acerba, the crystal crab Chaceon bicolor and the giant crab Pseudocarcinus gigas, all of which are fished commercially in these waters. This thesis reports the results of studies carried out on the biology of the first two species, for which there were previously very little information. The results increase our knowledge of the benthic fauna in deeper waters off the southwestern Australian coast and provide data that can be used by fisheries managers to develop plans for conserving the stocks of H. acerba and C. bicolor.
The champagne crab Hypothalassia acerba is found southwards of Kalbarri at ~ 27 degrees S, 114 degrees E on the west coast and eastwards to Eucla at ~ 32 degrees S, 129 degrees E on the south coast. There is a small commercial trap fishery for H. acerba on both the lower west and south coasts of Western Australia. However, on the west coast, H. acerba is managed as a single species fishery, whereas on the south coast it is a component of a multi-species fishery, which also includes the southern rock lobster Jasus edwardsii and P. gigas. On the west coast, the commercial catches of H. acerba increased sharply from ~ 1,500 kg in 1989 to reach maximum levels of 30-46,000 kg in 1997-99, reflecting a marked increase in fishing effort. However, it subsequently declined to essentially zero after 2000 due to effort shifting towards fishing for C. bicolor. Catches of H. acerba on the south coast peaked at 26-27,000 kg in 1997-98 but, in contrast to those on the west coast, remained relatively high in 2001 to 2003.
The crystal crab Chaceon bicolor occurs in water depths of ~ 450 to 1220 m around Australia and New Zealand. However the commercial fishery is almost entirely located between Carnarvon on the north-west coast at ~ 25 degrees S, 113 degrees E to approximately Windy Harbor at ~ 35 degrees S, 116 degrees E on the south coast. Commercial catches of C. bicolor in southwestern Australia, which came almost entirely from the lower west coast, rose from very low levels in 1997 to ~ 222,000 kg in 2001 and then remained close to this level in 2002 and 2003. These trends largely reflect an increase in fishing effort.
Hypothalassia acerba was sampled seasonally by setting traps at depths of 35, 90, 145, 200, 255, 310 and 365 m on the west and south coasts of Western Australia. Catch rates on the west and south coasts peaked sharply at depths of 200 and 145 m, respectively, but at similar temperatures of 16 - 17 degrees C. The catches on those coasts contained 69 and 84% males, respectively. The carapace length of H. acerba declined significantly by 4 mm for each 100 m increase in depth. Males attained a greater maximum carapace length than females on both the west coast, i.e. 135 vs 113 mm, and south coast, i.e. 138 vs 120 mm. Furthermore, after adjustment to a common depth of 200 m, the mean carapace length of males was greater than females on both the west coast (96.6 vs 94.6 mm) and south coast (101.5 and 91.4 mm) and the latter difference was significant (p < 0.001). These results thus show that, for H. acerba, (1) the distribution is related to depth and temperature, (2) body size is inversely related to water depth and (3) males grow to a larger size and are more prevalent in catches than females. There was also evidence that the distribution of H. acerba changed slightly with season and that there was spatial partitioning by this species and other large deep water invertebrate predators.
The trends exhibited by reproductive variables demonstrate that H. acerba reproduces seasonally on the lower west coast, with ovaries maturing progressively between July and December and oviposition occurring between January and March. The characteristics of H. acerba on the south coast differed in the following ways from those on the lower west coast. (i) No ovigerous females and only two females with egg remnants were caught. (ii) Ovaries did not develop late yolk granule oocytes until females had reached a larger size. (iii) Investment in gonadal development was less. These results strongly suggest that conditions on the south coast are not as conducive for ovarian development and reproduction and indicate that females migrate from the south to lower west coast for spawning. In contrast to H. acerba, C. bicolor reproduces throughout much or all of the year on the lower west coast, presumably reflecting its occupancy of far deeper waters where environmental conditions vary less during the year. Although the mean weights of ovigerous females of H. acerba and C. bicolor were not significantly different (p > 0.05), the mean fecundity of the former species (356,210) was significantly greater (p < 0.001) than that of the latter species (192,070). The relatively high fecundity of H. acerba may reflect adaptations by this species to optimise egg production during its relatively short breeding season.
The size at onset of sexual maturity (SOM) of the females of crustacean species, which is often used by fisheries managers for developing management plans for such species, is typically estimated using logistic regression analysis of the proportions of mature females in sequential size classes. The validity of this approach depends on the composition of the samples reflecting accurately that present in the environment. However, catches obtained by traps, a passive fishing method, typically contain disproportionately greater numbers of large crabs, whereas those obtained using active fishing methods, such as seine netting and otter trawling, will presumably represent far better the size composition of the population. Since H. acerba and C. bicolor could be caught in numbers only by using traps, comparisons between the influence of passive and active fishing methods were explored using the extensive data previously collected for Portunus pelagicus employing different sampling methods (de Lestang et al. 2003a,b). These data are analysed in order to demonstrate that the females of P. pelagicus caught by trapping were predominantly mature, whereas those obtained by seining and trawling contained numerous immature as well as mature females. The samples of females collected by trap are, therefore, clearly biased towards mature crabs. Consequently, for any size class, it would be predicted that the proportion of mature females in trap catches will be overestimated, thus shifting the logistic curve fitted to the proportions of mature crabs at each size to the left, and thereby yielding an underestimate of the SOM. This conclusion is substantiated by the fact that the carapace width of female P. pelagicus, at which 50% of individuals reach maturity (SOM50), was estimated to be markedly greater when using the proportion of mature females obtained by seine-netting and otter trawling collectively, i.e. 101.1 mm, than by trapping, i.e. 86.1 mm. From the above data for P. pelagicus, it is considered likely that, through a greater vulnerability of mature females of these species to capture by traps, the respective SOM50s derived for female H. acerba and C. bicolor from trap samples (i.e. carapace lengths of 69.7 and 90.5 mm) will represent considerable underestimates of the true SOM50s.
Many workers have assumed that the chelae of male crabs undergo a change in allometry at the pubertal moult and that this could thus be used as the basis for determining the size of those crabs at morphometric maturity. Since initial plots of the logarithms of propodus length and carapace width (CW) of the males of P. pelagicus and carapace length (CL) of the males of H. acerba and C. bicolor revealed no conspicuous change in allometry, the question of whether the chelae of these species undergo such an allometric change was explored statistically. The Akaike and Bayesian Information Criteria were thus used to ascertain whether a linear, quadratic, broken stick or overlapping-lines model best represented the above logarithmic size data. Since the broken stick model provided the best fit for P. pelagicus, the chelae of this species does undergo allometric change. This occurred at 80.0 mm CW, which is ~ 8 mm less than the CW at physiological maturity. In contrast, my analyses provided no evidence that the chelae of either H. acerba or C. bicolor exhibited an inflection and thus morphometric maturity could not be determined for these two species from chela length. Thus, mangers will have to use the SOM50 for physiological maturity, which was estimated to be 68.1 and 94.3 mm CL for H. acerba and C. bicolor, respectively.
25
Smith, Kimberley Dale. "Distributions, relative abundances and reproductive biology of the deep-water crabs Hypothalassia acerba and Chaceon bicolor in southwestern Australia." Smith, Kimberley Dale (2006) Distributions, relative abundances and reproductive biology of the deep-water crabs Hypothalassia acerba and Chaceon bicolor in southwestern Australia. PhD thesis, Murdoch University, 2006. http://researchrepository.murdoch.edu.au/318/.
Abstract:
Three species of large crab are found in Western Australian waters, namely the champagne crab Hypothalassia acerba, the crystal crab Chaceon bicolor and the giant crab Pseudocarcinus gigas, all of which are fished commercially in these waters. This thesis reports the results of studies carried out on the biology of the first two species, for which there were previously very little information. The results increase our knowledge of the benthic fauna in deeper waters off the southwestern Australian coast and provide data that can be used by fisheries managers to develop plans for conserving the stocks of H. acerba and C. bicolor.
The champagne crab Hypothalassia acerba is found southwards of Kalbarri at ~ 27 degrees S, 114 degrees E on the west coast and eastwards to Eucla at ~ 32 degrees S, 129 degrees E on the south coast. There is a small commercial trap fishery for H. acerba on both the lower west and south coasts of Western Australia. However, on the west coast, H. acerba is managed as a single species fishery, whereas on the south coast it is a component of a multi-species fishery, which also includes the southern rock lobster Jasus edwardsii and P. gigas. On the west coast, the commercial catches of H. acerba increased sharply from ~ 1,500 kg in 1989 to reach maximum levels of 30-46,000 kg in 1997-99, reflecting a marked increase in fishing effort. However, it subsequently declined to essentially zero after 2000 due to effort shifting towards fishing for C. bicolor. Catches of H. acerba on the south coast peaked at 26-27,000 kg in 1997-98 but, in contrast to those on the west coast, remained relatively high in 2001 to 2003.
The crystal crab Chaceon bicolor occurs in water depths of ~ 450 to 1220 m around Australia and New Zealand. However the commercial fishery is almost entirely located between Carnarvon on the north-west coast at ~ 25 degrees S, 113 degrees E to approximately Windy Harbor at ~ 35 degrees S, 116 degrees E on the south coast. Commercial catches of C. bicolor in southwestern Australia, which came almost entirely from the lower west coast, rose from very low levels in 1997 to ~ 222,000 kg in 2001 and then remained close to this level in 2002 and 2003. These trends largely reflect an increase in fishing effort.
Hypothalassia acerba was sampled seasonally by setting traps at depths of 35, 90, 145, 200, 255, 310 and 365 m on the west and south coasts of Western Australia. Catch rates on the west and south coasts peaked sharply at depths of 200 and 145 m, respectively, but at similar temperatures of 16 - 17 degrees C. The catches on those coasts contained 69 and 84% males, respectively. The carapace length of H. acerba declined significantly by 4 mm for each 100 m increase in depth. Males attained a greater maximum carapace length than females on both the west coast, i.e. 135 vs 113 mm, and south coast, i.e. 138 vs 120 mm. Furthermore, after adjustment to a common depth of 200 m, the mean carapace length of males was greater than females on both the west coast (96.6 vs 94.6 mm) and south coast (101.5 and 91.4 mm) and the latter difference was significant (p < 0.001). These results thus show that, for H. acerba, (1) the distribution is related to depth and temperature, (2) body size is inversely related to water depth and (3) males grow to a larger size and are more prevalent in catches than females. There was also evidence that the distribution of H. acerba changed slightly with season and that there was spatial partitioning by this species and other large deep water invertebrate predators.
The trends exhibited by reproductive variables demonstrate that H. acerba reproduces seasonally on the lower west coast, with ovaries maturing progressively between July and December and oviposition occurring between January and March. The characteristics of H. acerba on the south coast differed in the following ways from those on the lower west coast. (i) No ovigerous females and only two females with egg remnants were caught. (ii) Ovaries did not develop late yolk granule oocytes until females had reached a larger size. (iii) Investment in gonadal development was less. These results strongly suggest that conditions on the south coast are not as conducive for ovarian development and reproduction and indicate that females migrate from the south to lower west coast for spawning. In contrast to H. acerba, C. bicolor reproduces throughout much or all of the year on the lower west coast, presumably reflecting its occupancy of far deeper waters where environmental conditions vary less during the year. Although the mean weights of ovigerous females of H. acerba and C. bicolor were not significantly different (p > 0.05), the mean fecundity of the former species (356,210) was significantly greater (p < 0.001) than that of the latter species (192,070). The relatively high fecundity of H. acerba may reflect adaptations by this species to optimise egg production during its relatively short breeding season.
The size at onset of sexual maturity (SOM) of the females of crustacean species, which is often used by fisheries managers for developing management plans for such species, is typically estimated using logistic regression analysis of the proportions of mature females in sequential size classes. The validity of this approach depends on the composition of the samples reflecting accurately that present in the environment. However, catches obtained by traps, a passive fishing method, typically contain disproportionately greater numbers of large crabs, whereas those obtained using active fishing methods, such as seine netting and otter trawling, will presumably represent far better the size composition of the population. Since H. acerba and C. bicolor could be caught in numbers only by using traps, comparisons between the influence of passive and active fishing methods were explored using the extensive data previously collected for Portunus pelagicus employing different sampling methods (de Lestang et al. 2003a,b). These data are analysed in order to demonstrate that the females of P. pelagicus caught by trapping were predominantly mature, whereas those obtained by seining and trawling contained numerous immature as well as mature females. The samples of females collected by trap are, therefore, clearly biased towards mature crabs. Consequently, for any size class, it would be predicted that the proportion of mature females in trap catches will be overestimated, thus shifting the logistic curve fitted to the proportions of mature crabs at each size to the left, and thereby yielding an underestimate of the SOM. This conclusion is substantiated by the fact that the carapace width of female P. pelagicus, at which 50% of individuals reach maturity (SOM50), was estimated to be markedly greater when using the proportion of mature females obtained by seine-netting and otter trawling collectively, i.e. 101.1 mm, than by trapping, i.e. 86.1 mm. From the above data for P. pelagicus, it is considered likely that, through a greater vulnerability of mature females of these species to capture by traps, the respective SOM50s derived for female H. acerba and C. bicolor from trap samples (i.e. carapace lengths of 69.7 and 90.5 mm) will represent considerable underestimates of the true SOM50s.
Many workers have assumed that the chelae of male crabs undergo a change in allometry at the pubertal moult and that this could thus be used as the basis for determining the size of those crabs at morphometric maturity. Since initial plots of the logarithms of propodus length and carapace width (CW) of the males of P. pelagicus and carapace length (CL) of the males of H. acerba and C. bicolor revealed no conspicuous change in allometry, the question of whether the chelae of these species undergo such an allometric change was explored statistically. The Akaike and Bayesian Information Criteria were thus used to ascertain whether a linear, quadratic, broken stick or overlapping-lines model best represented the above logarithmic size data. Since the broken stick model provided the best fit for P. pelagicus, the chelae of this species does undergo allometric change. This occurred at 80.0 mm CW, which is ~ 8 mm less than the CW at physiological maturity. In contrast, my analyses provided no evidence that the chelae of either H. acerba or C. bicolor exhibited an inflection and thus morphometric maturity could not be determined for these two species from chela length. Thus, mangers will have to use the SOM50 for physiological maturity, which was estimated to be 68.1 and 94.3 mm CL for H. acerba and C. bicolor, respectively.
26
Rutherford, Jasmine Lee. "The role of geology, geomorphology, climate and vegetation, in controlling spatial and temporal changes in groundwater discharge from weathered crystalline basement aquifers in southwestern Australia." University of Western Australia. School of Earth and Geographical Sciences, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0006.
Abstract:
[Truncated abstract] The Collie River drainage basin is an important water resource catchment in southwestern Australia. Salinisation of a major water supply within the catchment, the Wellington Reservoir, has arisen due to changes in the water and salt balance in response to land clearing over saprolite aquifers. Paired catchment studies, the Collie Experimental Catchments (CECs), established in the early 1970’s in high and low rainfall areas increased our understanding of water and salt (predominantly chloride) movement in these aquifers through the collection and analysis of high resolution spatio-temporal data. However, the conceptual models developed from this work take little account of landscape heterogeneity, and this has caused problems in subsequent modelling studies, where success in calibrating stream flow has been countered by difficulties in predicting salt loads. The challenge remains to better describe variability in the Collie landscape and understand the influence of climate, vegetation, geology and geomorphology on observed water and salt fluxes. The release of salt from the lower saprolite aquifer and the role of the surficial aquifer in buffering groundwater discharge were investigated. The acquisition, analysis and interpretation of new regolith and geophysical data in 2001-2003 from the CECs, together with data from a high resolution digital elevation model, and existing drilling information, were used to construct a geologicalgeomorphological compartment framework, to observe changes in aquifer behaviour ... Significant differences in the salt flux from compartments have been noted at a range of scales, with implications for both water resource and land management. The approach developed to identify compartments and assess their efficiency could be simplified, using catchment critical parameters determined from geological and geomorphological characteristics. As a consequence, the implementation of a compartment framework in catchments with saprolite aquifers should allow for more informed decisions to be made in the selection of sites for revegetation strategies or the development of engineering works. This is particularly important in the Collie Catchment where reclamation scenarios are currently being discussed. Consideration of the catchment as a compartmentalised system would help manage salt loads in the Collie River and return the Wellington Reservoir to a functional water resource.
27
Scaccabarozzi, Daniela. "Pollination Ecology and Pollination Evolutionary Processes with Relevance in Ecosystem Restoration – Pollination Biology of Diuris: Testing for Batesian Mimicry in Southwestern Australia." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/77285.
Abstract:
The thesis demonstrates a unique pollination system in the Australian orchid genus Diuris via floral mimicry of multiple pea plants (Faboideae). In order to frame the pollination ecology of the putative model pea plants, we also verify the type of pollinator interactions (generalised vs specialized), occurring in communities of pea plants in the southwestern Australian Floristic Region (SWAFR). Our findings support one of the rare confirmed case of guild mimicry in plant world.
28
Rutherford, Jasmine Lee. "The role of geology, geomorphology, climate and vegetation, in controlling spatial and temporal changes in groundwater discharge from weathered crystalline basement aquifers in southwestern Australia /." Connect to this title, 2005. http://theses.library.uwa.edu.au/adt-WU2006.0006.
29
Olierook, Hugo K. H. "Tectono-stratigraphic evolution during rifting of the southwestern Australian margin." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/595.
Abstract:
Basin development and magmatism on the southwestern Australian margin are profoundly affected by continental breakup. Before and after breakup, sedimentary basins experienced regime switches in: fluvial-dominated to paralic sedimentation; paleo-drainage and provenance from south–north to east–west, and; locally heterogeneous subsidence and exhumation driven by tectonic events to more regionally homogeneous subsidence and exhumation driven predominantly by epeirogenesis. The breakup of eastern Gondwana resulted in coeval magmatism, driven by the Kerguelen mantle plume.
30
Mastalerz, Allison. "The role of ornamental gardening in forest plant invasions across an urban-rural gradient in Southwestern Ohio." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377866412.
31
Goldsworthy, Savita Delphini. "Assessing the current distribution of Southwestern Australian shallow-water reef fish assemblages in relation to management bioregions, and the change in these assemblages over time." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/83045.
Abstract:
This research documented the current distribution of shallow-water reef fish along ~2000 km of coastline in Southwest Australia and provided insights into how these assemblages have changed over the last 14 years. Fish communities formed four unique assemblages along the coast, with the boundaries of these assemblages differing from current management regions. These assemblages changed over the 14-year monitoring period with variations in the thermal niche, endemism and trophic level of species present.
32
Williams, Elizabeth. "Wet underfoot? Earth mound sites and the recent prehistory of southwestern Victoria." Phd thesis, 1985. http://hdl.handle.net/1885/109346.
Abstract:
Artificially constructed earth mounds are found in a number
of areas in Austalia and are associated with wetlands and localities
which have a high rainfall and poorly drained soils. Sites range in
size from 3m to 100m in diameter and 0.2 to 3 m in height. Previous
work suggested that mounds first appeared during the mid to late
Holocene. Some authors (e.g. Lourandos 1983: 85-87) see the introduction
of mounds as linked to an increase in production in prehistoric
economies, or 'intensification'.
My Ph.D research comprised a detailed study of mounds in one
region, southwestern Victoria. Ethnographic accounts note that mounds
here were used for a variety of purposes, including ovens, general
camping areas and as foundations for substantial huts. Archaeological
work, including survey, excavation, and geochemical and magnetic
sampling of sediments, shewed that mounds were used for the above
purposes in the prehistoric past. The study confirmed that mounds
appear relatively late in the prehistoric sequence, after 2500 yBP.
All but one site first appeared after 2000 yBP. This is well after
the introduction of certain technological changes such as the
'Australian small tool tradition', which probably entered the region
between 4 to 5000 years ago. The appearance of mounds does not appear
to be linked with this technological change and mounds instead seem to
be part of a sequence of generalised changes in site types and numbers
first appearing in the region about 2500 years ago. My research
suggests that these changes reflected shifts in a number of aspects of
prehistoric societies, including changes in the organisation of camps
and the use of labour,and a shift to a more long-term occupation of
settlements.
At present there is too little information to determine
whether only one prime mover was involved. Some authors (e.g. Beaton
1983) maintain that 'population pressure' was the major prime mover,
while others (e.g. Lourandos 1983, 1984) argue that changes were caused
by shifts in alliance networks, leading to 'intensification'. I
believe that both these factors were probably involved and that an
environmental shift to a wetter climate about 2000 years ago, also
contributed to these changes.
33
Barquero-Molina, Miriam. "Kinematics of bidirectional extension and coeval NW-directed contraction in orthogneisses of the biranup complex, Albany Fraser Orogen, Southwestern Australia." 2009. http://hdl.handle.net/2152/10567.
Abstract:
Granulite-facies orthogneisses of the Mesoproterozoic Albany-Fraser Orogen from the locality of Bremer Bay, in southwestern Australia, record at least three phases of widespread, pervasive NW- and NE-trending bidirectional extension that alternate with shortening and/or shear related structures. Crustal extension occurred ca. 1180 Ma, based on SHRIMP U–Pb zircon geochronology of melts generated during deformation, which coincided with Stage II (1215-1140 Ma) of the Albany-Fraser Orogeny, a period of NW-directed contraction. Eight different deformation phases can be recognized in the Bremer Bay area: (1) formation of a pervasive migmatitic fabric, defined by alternating leucosomes and melanosomes, parallel to the main compositional layering, and axial planar to localized isoclinal folds of cm-wide melt bands; (2) first bidirectional extension phase, which formed cm-scale square boudins of mafic layers parallel to the main migmatitic fabric; (3) formation of open to isoclinal, upright to overturned, SW-plunging, NW-verging m-scale folds of early square and rectangular boudins and dominant migmatitic foliation; (4) renewed coeval NE- and NW-directed extension that produced intermediate (< 1 meter to a few meters) boudins of the migmatitic fabric and compositional layering; (5) formation of regional-scale, NW-verging, SW-plunging overturned folds of all previous structures; (6) third phase of bidirectional extension that formed large, decameter-scale boudins of the migmatitic fabric; (7) late folding phase that resulted in the formation of m-scale open to tight, SW-plunging, upright to moderately overturned, NW-verging folds; and (8) fracturing related to the intrusion of dominantly N-NW- and N-NE-trending intermediate and felsic few cm- to few dm-wide pegmatite veins. Melt generation was concurrent with all stages of deformation. The Albany-Fraser Orogen is reinterpreted as a diachronous orogen, resulting from the closure of the asymmetrically shaped ocean basin between the West Australian and Mawson cratons, which widens considerably from NE to SW along the length of the orogenic front. Subduction on the western side of the orogen was the driving force for NW-directed collision during Stage II of the orogeny. Slab breakoff and orogenic collapse following closure of an intracratonic ocean basin could account for the multiple phases of bidirectional extension, granulite facies metamorphism and pervasive partial melting throughout deformation.text
34
Lee, Peter Sang-Hoon. "Predicting bird habitat resources in temperate woodlands using remotely sensed data : case study in the Great Western Woodlands, southwestern Australia." Phd thesis, 2011. http://hdl.handle.net/1885/150319.
Abstract:
Scant data exist that can inform conservation planners in the Great Western Woodlands (GWW). Yet this extensive area of temperate woodland in southwestern Western Australia is vital for the conservation of many woodland bird species. In this thesis, a modelling approach was developed for predicting the potential distribution of woodland bird habitat functional groups in GWW as a function of their habitat resource use. This model was generated from remotely sensed data-based inputs in conjunction with published bird habitat resource information. Habitat resource information was collected from published literature related to woodland and/or GWW bird species. Based on this information, vegetation structure-related habitat resources were identified and 104 GWW bird species were classified into Bird habitat functional groups (BHFGs). To analyse vegetation structure within GWW, four different satellite-borne data sets (MODIS, ASTER, PALSAR and GLAS) were analysed. The ability of different remote sensing technologies to identify vegetation structure variables was evaluated by comparing remotely sensed data to data collected in the field for selected vegetation sites. The variables were used to model vegetation structure in the landscape of GWW. A bird habitat resource classification model was developed with the nine BHFGs based on the vegetation structure-related habitat resources identified through the literature review. Each spatial data layer derived from the four satellite data sets provided values correlated with five specific Vegetation structure variables: Vegetation cover from ASTER; Foliage density from MODIS; Shrub layer complexity from ASTER; Vegetation volume from PALSAR; and Vegetation height from GLAS. The vegetation structure-based data layers were combined into a three-dimensional Landscape prediction of vegetation structure variables (LPVSV) for predicting bird habitat types derived in terms of the Vegetation structure variables. The BHFGs and the LPVSV were then combined into a Potential bird habitat functional group spatial prediction system (PBHFG-SPS). Due to the lack of field observation on birds in GWW, the predictive capability of the PBHFG-SPS could not be tested. Difficulties in investigating the GWW landscape and the limitations of available data and information about GWW are discussed, as are methods for improving the model developed in this study. The approach developed in this thesis was considered useful for investigating vegetation structure for the purpose of bird conservation, given the limited biophysical field data over extensive and remote areas such as GWW.
35
Merrett, H. D. "2D lithospheric imaging of the Delamerian and Lachlan Orogens, southwestern Victoria, Australia from Broadband Magnetotellurics." Thesis, 2016. http://hdl.handle.net/2440/121124.
Abstract:
This item is only available electronically.A geophysical study utilising the method of magnetotellurics (MT) was carried out across southwestern Victoria, Australia, imaging the electrical resistivity structure of the lithosphere beneath the Delamerian and Lachlan Orogens. Broadband MT (0.001-1000 Hz) data were collected along a 160 km west-southwest to east-northeast transect adjacent to crustal seismic profiling. Phase tensor analyses from MT responses reveal a distinct change in electrical resistivity structure and continuation further southwards of the Glenelg and Grampians-Stavely geological zones defined by the Yarramyljup Fault, marking the western limit of exploration interest for the Stavely Copper Porphyries. The Stawell and Bendigo Zones also show change across the Moyston and Avoca faults, respectively. Results of 2D modelling reveal a more conductive lower crust (10-30 Ωm) and upper mantle beneath the Lachlan Orogen compared to the Delamerian Orogen. This significant resistivity gradient coincides with the Mortlake discontinuity and location of the Moyston fault. Broad-scale fluid alteration zones were observed through joint analysis with seismic profiling, leaving behind a signature of low-reflectivity, correlating to higher conductivities of the altered host rocks. Isotopic analysis of xenoliths from western Victoria reveal the lithospheric mantle has undergone discrete episodes of modal metasomatism. This may relate to near-surface Devonian granite intrusions constrained to the Lachlan Orogen where we attribute the mid to lower crustal conductivity anomaly (below the Stawell Zone) as fossil metasomatised ascent paths of these granitic melts. This conductivity enhancement may have served to overprint an already conductive lithosphere, enriched in hydrogen from subduction related processes during the Cambrian. A predominately reflective upper crust exhibits high resistivity owing to turbidite and metasedimentary rock sequences of the Lachlan Orogen, representative of low porosity and permeability. Conductive sediments of the Otway Basin have also been imaged down to 3 km depth southwest of Hamilton.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2016
36
Apak, Sukru N. "Structural development and control on stratigraphy and sedimentation in the Cooper Basin, northeastern South Australia and southwestern Queensland / by Sukru N. Apak." 1994. http://hdl.handle.net/2440/21506.
Abstract:
Bibliography: leaves 94-105.xvi, 105, [91] leaves : ill. (some col), maps (some col.) ; 30 cm. 50 maps in box; 35 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, National Centre for Petroleum Geology and Geophysics, 1995?
37
Apak, Sukru N. "Structural development and control on stratigraphy and sedimentation in the Cooper Basin, northeastern South Australia and southwestern Queensland / by Sukru N. Apak." Thesis, 1994. http://hdl.handle.net/2440/21506.
Abstract:
Bibliography: leaves 94-105.xvi, 105, [91] leaves : ill. (some col), maps (some col.) ; 30 cm. 50 maps in box; 35 cm.
Thesis (Ph.D.)--University of Adelaide, National Centre for Petroleum Geology and Geophysics, 1995?