West Australia Research Articles

The enigma of rare Quaternary oolites in the Indian and Pacific Oceans: A result of global oceanographic physicochemical conditions or a sampling bias?

Marine ooids are iconic indicators of shallow seawater carbonate saturation state, and their formation has traditionally been ascribed to physicochemical processes. The Indo-Pacific stands out as a region devoid of oolites, particularly during the Quaternary: the “ooid enigma”. Here we present results from recent coring by the International Ocean Discovery Program (IODP Expedition 356) off west Australia that shows that ooid horizons are common in Pleistocene strata up to 730,000 years old. Extensive “ooid factories” were created due to the presence of long-lived tidally influenced flat–topped tropical platforms suitable for intermittent ooid accretion over hundreds to thousands of years during highstands and times of lower sea level. This work suggests marine ooids may actually be more common in Indo-Pacific than previously reported. Past global ocean alkalinity was elevated during Pleistocene glacial periods and continental climate was generally more arid in the Indo-Pacific region compared to interglacials and the Holocene. Therefore, increased aridity associated with higher alkalinity conditions during the glacials facilitated ooid precipitation on adjacent tropical carbonate platforms particularly offshore from arid Australia. This confluence of factors suggests that more “ooid factories” may be encountered by further coring Indo-Pacific regions with Pleistocene flat long-lived carbonate shelves. However, Indo-Pacific Quaternary ooid occurrences outside Australia are rare, suggesting that the Northwest Shelf may be a unique archive of this non-skeletal precipitate. Further investigations into the petrography and geochemistry of pre-Holocene ooid occurrences will provide insights into their origin and the relative role of biotic, physicochemical and other factors in their formation.

Drugs for treating Buruli ulcer (Mycobacterium ulcerans disease).

Drugs for treating Buruli ulcer (Mycobacterium ulcerans disease).

The amplifying effect of Indonesian Throughflow heat transport on Late Pliocene Southern Hemisphere climate cooling

An unusually short glaciation interrupted the warm Pliocene around 3.3 Ma (Marine Isotope Stage (MIS) M2). Different hypotheses exist to explain why this glaciation event was so pronounced, and why the global climate system returned to warm Pliocene conditions relatively quickly afterwards. One of these proposed mechanisms is a reduced equator-to-pole heat transfer, in response to a tectonically reduced Indonesian Throughflow (ITF). The ITF is a critical part of the global thermohaline ocean circulation, transporting heat from the Indo-Pacific Warm Pool to the Indian Ocean. When ITF connectivity is reduced, the water and heat supply for the Leeuwin Current, flowing poleward along Australia's west coast, is also diminished. To assess the possible relationship between mid-Pliocene glaciations and latitudinal heat transport through the Indonesian Throughflow, we constructed a multi-proxy orbital-scale record for the 3.7–2.8 Ma interval from International Ocean Discovery Program (IODP) Site U1463, off northwest Australia. The comparison of the Site U1463 record with paleoclimate records from nearby Site 763 and West Pacific Warm Pool Site 806 allows for a detailed regional reconstruction of Pliocene paleoceanography and thus for testing the proposed hypothesis.An astronomically-paced decrease in potassium content characterizes the late Pliocene interval of U1463. This record documents the increasing aridity of northwest Australia, periodically alleviated by reinforced summer monsoon precipitation under summer insolation maxima. The δ18O record of the planktonic foraminifer Globigerinoides sacculifer correlates exceptionally well with the sea surface temperature (SST) record from Site 806 in the West Pacific Warm Pool, even during MIS M2. Hence, Site U1463 preserves an uninterrupted ITF signal even during Pliocene glaciations. However, the U1463 δ18OG.sacculifer record exhibits a 0.5‰ offset with the nearby Site 763A record around MIS M2. This implies that Site 763A, about 500 km west of U1463, more closely tracks Indian Ocean SST records across MIS M2. The U1463 data reveal that heat-transport through the Indonesian Throughflow did not shut down completely during MIS M2, but rather its intensity decreased prior to and during MIS M2, causing Site 763A to temporarily reflect an Indian Ocean, rather than an ITF signal. We conclude that ITF variability significantly influenced latitudinal heat transport by means of the Leeuwin Current and hence contributed to the relative intensity of MIS M2. We propose the ITF valve between the Pacific and Indian Ocean as a positive feedback mechanism, in which an initial sea level lowering reduces ITF heat transport, in turn amplifying global cooling by advancing the thermal isolation of Antarctica.

Waves along Eastern boundary currents – The regional winds effect

The wind fields along the five eastern boundary currents (EBC) systems (California, Canary, Humboldt, Benguela, and West Australia) are highly seasonal. This seasonality is mostly determined by the position of the semi-permanent high pressure cells over the ocean. During summer these high pressure cells, with a thermal low pressure systems inland, are the synoptic drivers of along coast winds. These strong summer winds, along the EBC systems, off-shore mid-latitude continental coasts, generate waves that can be rather extreme, considering that these areas can be seen as limited fetch wave fields. A qualitative analysis of the wave climate over the mid-latitudes western coastal areas, along the five EBC systems, based on the ERA-Interim reanalysis wave data, is presented. The influence of coastal wind speed intensification processes in these areas, like the occurrence of coastal low-level jets, and expansion fans in the lee of headlands and capes, on the local wave field is studied. It is shown that, despite the distance between the five EBC systems, their wave fields, particularly during summer, are very similar when the wind sea and swell characteristics are balanced. In summer locally generated wave heights and energy content, along EBC areas, are comparable or even higher than swell ones.

The secular development of accretionary orogens: linking the Gondwana magmatic arc record of West Antarctica, Australia and South America

Combined zircon geochronology and Hf isotopes of plutonic rocks from eastern Marie Byrd Land and Thurston Island, Antarctica, provide a detailed record of Phanerzoic arc magmatism along the paleo-Pacific margin of Gondwana. Magmatism along the Antarctic margin initiated in a dominantly contractional arc setting with an isotopically enriched lithospheric mantle source during the Ross Orogeny (c. 540–485 Ma). After termination of the Ross Orogeny through the Cretaceous, detrital zircon and zircon from igneous rocks record relative increases in zircon εHfi inferred to represent episodes of lithospheric-scale extension and relative decreases during inferred contractional episodes along the Antarctic margin. Comparison of this secular isotopic evolutionary trend with similar data from along the paleo-Pacific margin of Gondwana demonstrates a shared history among Marie Byrd Land, Australia, and Zealandia that contrasts with the shared record of Thurston Island, Antarctic Peninsula, and South America. These two contrasting histories highlight an early Permian along arc geochemical and inferred geodynamic switch from an isotopically enriched contractional arc system in South America, Antarctic Peninsula, and Thurston Island to an isotopically depleted extensional arc system in Marie Byrd Land, Zealandia, and Australia. Despite differences in timing, all segments of the paleo-Pacific margin underwent a similar secular isotopic evolution with dramatic shifts from enriched to juvenile isotopic compositions during extensional collapse.

Transmission electron microscopy of impact‐generated platinum group element alloys from Barberton spherule layers: New clues to their formation

AbstractThe oldest known large bolide impacts onto Earth are represented by approximately 3.47–3.2 Ga old Archean spherule layers of the Barberton Greenstone Belt (BGB) in South Africa and the Pilbara craton in West Australia. These layers were recognized as impact deposits by their excessively high platinum group element (PGE) contents that are indicative of an extraterrestrial component. This was followed by measurements of extraterrestrial Cr isotopic ratios, in some cases. Recently, the extraterrestrial PGE signature in Archean spherule layers from the BGB was localized and positively associated with the presence of submicrometer PGE alloy micronuggets associated with Ni,Cr‐rich spinel. The actual formation of these platinum group mineral (PGM) phases has, however, not yet been resolved. Primary meteoritic particles from the impacting body, the products of impact melting, or condensation from impact vapor plumes have all been proposed as possible genetic process. Resolving this requires detailed microanalytical investigation of the internal microchemical and microstructural compositions, textural characteristics, and crystallographic relationships between the different phases. Here, we report the results of a first transmission electron microscopy (TEM) study of six such PGE microparticles enclosed in Ni‐Cr spinel or occurring in groundmass of Barberton spherule layers from the BARB5 ICDP drill core and from the CT3 exploration core. Results include a variety of chemical and structural PGM compositions that are difficult to explain by a single process, leading to the conclusion that several processes may have been involved in the formation of PGMs in Archean spherule layers from the BGB. There is evidence supporting formation of these PGMs by exsolution from the spinel host phase, precipitation from a melt phase, and condensation from a gas phase (of the impact vapor plume).

Petrogenesis of Mesoproterozoic mafic rocks in Hainan (South China) and its implication on the southwest Hainan-Laurentia-Australia connection

New U-Pb geochronological, elemental and Nd-Hf isotopic data for the metamorphic mafic rocks from the Baoban Complex in southwest Hainan provide new constraints on their petrogenesis and geodynamic setting. Magmatic zircons from the representative samples yielded weighted mean 207Pb/206Pb ages of 1441–1424 Ma, representing their crystallization ages. These samples show subalkaline to alkaline characteristics and can be geochemically subdivided into three groups in spite of similar formation time. Group 1 has TiO2 of 2.85–3.18 wt.%, Nb of 20.5–21.6 ppm, Nb/U of 45–49, Nb/La of 1.22–1.37, εNd (t) of +6.8–+6.9 and zircon εHf (t) of +9.3–+12.7, suggestive of the derivation from OIB-like source. Group 2 shows Nb contents ranging from 1.0 ppm to 12.6 ppm, εNd (t) values from +5.5 to +5.9 and zircon εHf (t) values from +10.3–+12.4 with right-sloping REE-normalized pattern, indicative of an E-MORB source. Group 3 is characterized by negative Nb-Ta anomalies with Nb/La ratios of 0.51–0.88 and εNd (t) value of ∼+5.1, indicative of the derivation from a previously-metasomatized mantle source. The coeval mafic and felsic rocks in the Baoban Complex are geochronologically and geochemically comparable to the Mesoproterozoic intra-plate magma in southwest Laurentia. The Mesoproterozoic Baoban igneous rocks are generated in a syn-rift setting in response to the Columbia breakup. Southwest Hainan might connected with west Laurentia and Australia at ∼1.43 Ga.

The Kalkarindji Large Igneous Province, Australia: Petrogenesis of the Oldest and Most Compositionally Homogenous Province of the Phanerozoic

The Kalkarindji Large Igneous Province (LIP) is a Middle Cambrian (511 Ma) continental flood basalt (CFB) province located in northern and central–west Australia that has been linked to an extincti ...

Why is south west Australia's ecology so special?

Why is south west Australia's ecology so special?

Trends in wheat yields under representative climate futures: Implications for climate adaptation

Underestimating the impacts of climate change on agricultural production could lead to complacency about the potential adaptation challenges. This study used a Representative Climate Futures (RCF) approach to model projected wheat yields under climate change in Australia. It simulated the range of impacts, resulting from a subset of individual Global Climate Models (GCMs), on wheat production in the major wheat regions of Australia. The study used RCFs that represented ‘most-likely’, ‘best’ and ‘worst’ cases across multiple Representative Concentration pathways (RCPs). Median wheat yields modelled for the South West Australia projected declines between 26% and 38%, under a ‘most-likely’ case for RCP 4.5 by 2090, and between 41% and 49%, under a ‘most-likely’ case for RCP 8.5. Median wheat yields declined under RCP 8.5 for the ‘most-likely’ case across the majority of wheat producing regions, with a range of 1% to 49%. Greater declines were projected under the ‘worst’ cases of hottest and driest climates. However, the ‘best’ cases of least warm and wetter climates projected an increase in median wheat yield, a range of 2% to 87%. Variability also changed from the baseline under all projected RCFs and across all regions, with a standard deviation of up to 2.46t/ha under the ‘most likely’ case at a site in south-eastern Australia. These likely shifts in the size and reliability of yields, combined with concurrent climate change impacts on other factors, mean that agriculture faces significant adaptation challenges, particularly under some of the ‘most-likely’ scenarios and all of the ‘worst’ case scenarios. Further work is required to explore how scenarios in one region relate to those in other regions and thus the overall outcome at the continental scale.

Geometric and depositional responses of carbonate build-ups to Miocene sea level and regional tectonics offshore northwest Australia

The geometric and depositional responses of isolated carbonate build-ups to Miocene sea-level change and regional tectonics was investigated using a combination of 3D seismic and borehole data from the Browse Basin, North West Australia, and outcrop information from the Cariatiz Reef, southeast Spain. The interpreted seismic volume documents five (5) Miocene sequence boundaries and five (5) main seismic facies. Seismic attribute analyses proved a highly effective tool for interpreting carbonate facies but, when compared with outcrop information from southeast Spain, data are limited to large-scale features of scales beyond 16.4 m vertically and 18.75 m horizontally. Hence, this work clearly shows that estimations of reservoir potential are significantly underestimated if based on seismic data alone. As a corollary of the structural analysis in this work, growth patterns suggest Messinian structural partitioning across the Browse Basin, with deformation associated with plate collision focused in preferentially orientated faults - thus only influencing carbonate build-up evolution at a local scale.

Detrital zircon U-Pb geochronology and provenance of the Sanxiatian Formation (Huade Group) in the North China Craton: Implications for the breakup of the Columbia supercontinent

The tectonic evolution and Paleoposition of the North China Craton (NCC) in the Columbia supercontinent during Mesoproterozoic is still not well constrained owing to scarce outcrops of the Mesoproterozoic geological records. Here we present detailed U-Pb geochronological study on detrital zircons and trace elemental geochemistry of the Mesoproterozoic meta-sedimentary rocks from the Sanxiatian Formation, the upper Huade Group, in the northern NCC. The youngest cluster of detrital zircons from the Sanxiatian Formation has U-Pb age peak at ∼1357 Ma, which constrains the deposition of the Sanxiatian Formation after ∼1400 Ma. We suggest a stratigraphic correlation among the Sanxiatian, Baiyinbaolage, Liuhongwan and Xiamaling formations, all of which were deposited simultaneously in the northern NCC. The small portion of ∼2530 Ma zircons possibly corresponds with the growth of juvenile crust in the NCC at the late Neoarchean. The distinct ∼1850 Ma population may have originated from the syn-and post- tectonic granites distributed in the Trans-North China Orogen (TNCO), which is related with the collision between the Western and Eastern blocks in the NCC. The ∼1750–∼1600 Ma zircon populations were also sourced from the NCC and are possibly characterized by the post-collisional magmatic events after the amalgamation of the NCC. The zircon clusters younger than 1600 Ma with peaks at ∼1575 Ma and ∼1357 Ma, were interpreted as exotic sources, while the latter possibly related with the final breakup of the supercontinent Columbia. With the compilation of the detrital zircon dataset from the North India, the West Australia, the North Australia, the Siberia blocks and the northwestern Laurentia, the final fragmentation of the supercontinent Columbia is suggested to be characterized by the separation between the NCC, the Australia or the India blocks during the late Mesoproterozoic.

Slowing Down on the Path to Knowledge

Slowing Down on the Path to Knowledge Paul Stoller Michael D. Jackson, As Wide as the World is Wise: Reinventing Philosophical Anthropology. New York: Columbia University Press, 2016. 272 pp. Michael D. Jackson, The Work of Art: Rethinking the Elementary Forms of Religious Life. New York: Columbia University Press, 2016. 256 pp. Elders among the Songhay people of the Republics of Niger and Mali long ago taught me an important lesson: it takes a great deal of time to learn important things. As a young and impatient student, I asked too many questions and pushed my teachers about the deep truths of Songhay culture. They politely refused. They told me that my mind was too young to learn important things. They said that the mind stretches with time-in-the-world. When age and collective experience have ripened a person's mind, he or she is then ready to receive the wise truths of the ancestors. What can a young mind, they would ask rhetorically, comprehend about being a human being? Although their orientation to learning frustrated me at first, I gradually became more and more appreciative of their slow epistemology. In time, I came to understand more [End Page 393] fully the wisdom of taking a slower approach to anthropology, an approach that provides ample time for the maturation of knowledge. When considering the corpus of Michael Jackson's anthropological work, the benefits of a slow and sustained approach to anthropology become powerfully obvious. You could suggest that Jackson practices a fast anthropology. He has, after all, published more books (poetry, ethnographies, memoirs, and collections of essays) than I can count. These books are wonderfully varied in scope and subject and are written with the precision and craft of a poet. And yet, if you follow the development of Jackson's thought, it becomes clear—at least to me—that a slow approach to the acquisition of knowledge has shaped his thinking about the human condition. ________ We live in complex and unstable times. There are no quick-fix answers to the political, social, and intellectual problems of the current era. Given the multiplex whys and wherefores of contemporary life, is it still possible to make sense of the human condition? What knowledge can anthropologists contribute to this ever-important question? Can anthropological wisdom chart a path that leads to a life well-lived? Can it provide us with a roadmap toward well-being in the world? In Jackson's latest books—one on reinventing philosophical anthropology and one on the power of art in shaping the contours of social life—the author explores these vexing questions with perspicacity. Indeed, these are the big questions that define human being-in-the world. In As Wide as the World is Wise, Jackson elegantly explores the spaces between things—murky spaces in which human beings are always already, to borrow from Jacques Derrida, situated. These are spaces that escape brute categorization. They are spaces that are defiantly non-concrete. For his epigraph, Jackson quotes Jacques Derrida. The logocentrism of Greek metaphysics will always be haunted…by the "absolutely other" to the extent that the Logos can never englobe everything. There is always something which escapes, something different, something other and opaque which refuses to be totalized into a homogeneous identity. (Derrida 1984:117) [End Page 394] In this wonderfully crafted work, Jackson is our guide to those existential spaces that are different and opaque. After more than 40 years of fieldwork in West Africa and Australia, after a lifetime of reading, reflection, and writing about living-in-the-world, Jackson has produced a work that describes how his experience directed him to follow the sinuous, nontotalizing path between things—between the one and the many, between identity and difference, between ourselves and others, between the personal and the professional, between belief and experience, between being and thought, between fate and freewill, between center and periphery. As Wide as the World is Wise, then, is a book that explores the imaginative spaces between anthropology and philosophy. This work is rich, deep, and textured. It showcases Jackson's erudition and his skill as a writer. Given the limitations of space, I cannot dive...

Environmental contributions to gastrointestinal and liver cancer in the Asia–Pacific region

In the Asia-Pacific region, gastric, colorectal, and hepatocellular (liver) cancer show substantial regional variation in incidence consistent with the presence of important environmental factors. For gastric cancer, global incidence is concentrated in Asia with substantially higher rates in East Asia than in South-East Asia and Australia. The differences in incidence rates for gastric cancer in the Asia-Pacific region may be due, in part, to differences in the prevalence of Helicobacter pylori infection and the prevalence of H.pylori virulence factors. Smoking is also correlated with gastric cancer risk and is responsible for the highest population attributable fraction among men in East Asia. Colorectal cancer has increased rapidly in incidence to become the third most common digestive cancer in Asia. According to cohort studies in Asia, smoking, alcohol use, obesity, and physical inactivity increase the risk of colorectal cancer. Unlike West Asia, East Asia and Australia have high incidence rates for colorectal cancer that correlates to a high Human Development Index and a high prevalence of alcohol consumption and obesity. Liver cancer is the second most common digestive cancer in Asia. The high incidence of liver cancer in East Asia and South-East Asia is concordant with the high prevalence of hepatitis B virus and hepatitis C virus infection. Other important risk factors include alcohol use, smoking, and diabetes. The identification of the earlier and other environmental factors (currently under investigation) is central to the development and implementation of effective cancer control programs for the region.

The drying tendency of shallow meridional circulations in monsoons

Shallow meridional overturning circulations are superimposed on the deep circulations that produce precipitation in nearly all monsoon regions, and these shallow circulations transport subtropical, mid‐tropospheric dry air into the tropical monsoon precipitation maxima. Here horizontal moisture advection produced by shallow meridional circulations is characterized in the monsoon regions of West Africa, South Asia, Australia, and southern Africa during local summer. Horizontal flow in the upper and lower branches of the shallow meridional circulations consistently dries and moistens air, respectively, in the continental precipitation maxima of each region. The peak drying by horizontal advection occurs at a lower altitude than peak winds in the upper branch of the shallow circulations, consistent with the small scale height of water vapour. Advection of time‐mean moisture by time‐mean wind dominates horizontal moisture advection in South Asia and West Africa, while most horizontal moisture advection in Australia and southern Africa is produced by transient eddies. Much of the transient eddy advection can be accurately represented as a first‐order horizontal diffusion with a constant, globally uniform diffusivity. These results suggest that horizontal moisture advection in theoretical and conceptual models of seasonal mean monsoons can be adequately represented in terms of time‐mean winds plus a simple horizontal moisture diffusion. Finally, interannual variations in the summer mean regional averages of monsoon precipitation and horizontal advective drying in the lower free troposphere are shown to be negatively correlated in most regions, consistent with the hypothesis that advective drying by shallow meridional circulations inhibits monsoon precipitation.

Characterizing carbonate facies using high-definition frequency decomposition: Case study from North West Australia

Carbonate facies identification is difficult using conventional seismic attributes due to subtle lithologic changes that cannot be easily recognized. Therefore, there is a need to develop new methodologies to study their evolution and their associated sedimentary processes, which will eventually lead to better prediction for reservoir-quality rocks. New insights into the Cenozoic carbonates in North West Australia have been captured with the application of a high-definition seismic attribute workflow. The workflow starts with conditioning of the seismic volume using structurally oriented noise attenuation filters to remove any random and coherent noise from the input data. It also benefits from a high-definition frequency decomposition that matches the original seismic resolution without smearing interfaces using a “matching pursuit” algorithm. A color blend of multigeometric attributes, such as semblance and conformance, has also been used in the workflow to define edges and discontinuities present in the data within carbonate deposits that are attributed to depositional geometries, such as barrier reefs. Our workflow has been developed to investigate the geomorphology and the sedimentary processes affecting Cenozoic successions in the Northern Carnarvon Basin in North West Australia. Geomorphological and sedimentological observations have been documented such as an Eocene rounded carbonate ramp with evidence of slump blocks and scarps, Middle Miocene accretions generated due to longshore drift, and the presence of Pliocene-Pleistocene patch and barrier reefs. These observations were extracted as geobodies to allow for visualization, and they can be used in an automated seismically based facies classification scheme. The new appreciations are not only useful for understanding the carbonate evolution but can also be used to identify geohazards such as slumps ahead of future drilling.

Movement, distribution and marine reserve use by an endangered migratory giant

AbstractAimUnderstanding the spatial and temporal variation in the distribution of migratory species is critical for management and conservation efforts. However, challenges in observing mobile marine species throughout their migratory pathways can impede the identification of critical habitat, linkages between these habitats and threat‐mitigation strategies. This study aimed to gain insight into the long‐term residency and movement patterns of the whale shark (Rhincodon typus) and to reveal important habitat in the context of R. typus usage of existing Marine Protected Areas (MPAs).LocationSouth‐eastern Indian Ocean.MethodsSatellite telemetry was used to remotely track the long‐term movements of 29 R. typus, and to quantify shark usage of the existing MPA network. From the tracking data and environmental predictors, nonlinear models were developed to predict suitable R. typus habitat throughout the south‐eastern Indian Ocean.ResultsThis study includes the first documented complete return migrations by R. typus to Ningaloo Marine Park, which was found to be an important area for R. typus all year‐round. We found that while existing MPAs along Australia's west coast do afford some protection to R. typus, telemetry‐based habitat models revealed large areas of suitable habitat not currently protected, particularly along the Western Australian coast, in the Timor Sea, and in Indonesian and international waters.Main conclusionsAnimal‐borne telemetric devices allowed the gathering of long‐term spatial information from the elusive and highly mobile R. typus, revealing the spatial scale of their migration in the south‐eastern Indian Ocean. Suitable habitat was predicted to occur inside conservation areas, but our findings indicate that the current MPA network may not sufficiently protect R. typus throughout the year. We suggest that telemetry‐based habitat models can be an important tool to inform conservation planning and spatial management efforts for migratory species.

Sesquiterpene Variation in West Australian Sandalwood (Santalum spicatum)

West Australian sandalwood (Santalum spicatum) has long been exploited for its fragrant, sesquiterpene-rich heartwood; however sandalwood fragrance qualities vary substantially, which is of interest to the sandalwood industry. We investigated metabolite profiles of trees from the arid northern and southeastern and semi-arid southwestern regions of West Australia for patterns in composition and co-occurrence of sesquiterpenes. Total sesquiterpene content was similar across the entire sample collection; however sesquiterpene composition was highly variable. Northern populations contained the highest levels of desirable fragrance compounds, α- and β-santalol, as did individuals from the southwest. Southeastern populations were higher in E,E-farnesol, an undesired allergenic constituent, and low in santalols. These trees generally also contained higher levels of α-bisabolol. E,E-farnesol co-occurred with dendrolasin. Contrasting α-santalol and E,E-farnesol chemotypes revealed potential for future genetic tree improvement. Although chemical variation was evident both within and among regions, variation was generally lower within regions. Our results showed distinct patterns in chemical diversity of S. spicatum across its natural distribution, consistent with earlier investigations into sandalwood population genetics. These results are relevant for plantation tree improvement and conservation efforts.

Hydrological response to bauxite mining and rehabilitation in the jarrah forest in south west Australia

Study regionJarrah forest in south west Australia. Study focusThe hydrological response to bauxite mining in the jarrah forest could differ from other land uses such as timber harvesting or clearing for agriculture, since mining involves excavation of the upper regolith in addition to changes in forest cover due to clearing and subsequent rehabilitation. Three catchments, one subject to mining, a second subject to an intensive forest thinning treatment and an untreated control were monitored for streamflow, rainfall, groundwater and leaf area index over a 36-year period. New hydrological insights for the regionMining caused a peak streamflow response of 225mm or 18% of rainfall, before returning to pre-disturbance levels 11 years after mining commenced. Streamflow changes were closely associated with changes in a groundwater discharge area in the valley floor. Changes in groundwater level, in turn, were related to rainfall and leaf area index, and these effects did not differ between mine rehabilitation and unmined catchment areas. The streamflow response to mining could not be distinguished from the intensive thinning treatment in this study, or from clearfelling or clearing for agriculture reported elsewhere in the jarrah forest. The results indicate that shallow subsurface flow processes, considered to dominate streamflow generation in jarrah forest catchments, do not extend beyond the valley floor and immediately adjacent slopes which were not disturbed by mining.

Phylogeography of the mouth-brooding freshwater fish Glossamia aprion (Apogonidae) in northern and eastern Australia: historical biogeography and allopatric speciation

We examined the influence of past and present landscape structure across five regions of northern and eastern Australia on phylogeographic structure in the freshwater fish Glossamia aprion. We predicted the geological isolation of North West Australia would promote the strongest phylogeographic structure, including highest endemism of candidate species and deepest divergences within species, and past low sea level riverine connections in the Carpentaria Region would greatly reduce phylogeographic structure. The allozyme data indicated five candidate species within Australian Glossamia, although the mtDNA data revealed only four of these taxa. Diversity and endemism of the candidate species was highest in North West Australia, but Carpentaria was not the only region to have low species diversity or an absence of endemic species. Three of the five candidate species were narrow range endemics and occurred in regions with known endemism of candidate species in other freshwater fauna. The reported subspecies Glossamia aprion gillii was clearly distinct based on the genetic data, while the fifth species, G. a. aprion, was widely distributed across four of the five regions. The intra-specific analyses for G. a. aprion showed highest phylogeographic structure in North West Australia and lowest phylogeographic structure in Carpentaria. Overall, the results demonstrate the long-term legacy of variable landscape structure on phylogeographic patterns and allopatric speciation.