Isotopic compositions are referred to as anomalous if the isotopic ratios measured cannot be related to the terrestrial (solar) composition of a given element. While small effects close to the resolution of mass spectrometric techniques can have ambiguous origins, the discovery of large isotopic anomalies in inclusions and grains from primitive meteorites suggests that material from distinct sites of stellar nucleosynthesis has been preserved. Refractory inclusions, which are predominantly composed of the refractory oxides of Al, Ca, Ti, and Mg, in chondritic meteorites commonly have excesses in the heaviest isotopes of Ca, Ti, and Cr which are inferred to have been produced in a supernova. Refractory inclusions also contain excess 26Mg from short lived 26Al decay. However, despite the isotopic anomalies indicating the preservation of distinct nucleosynthetic sites, refractory inclusions have been processed in the solar system and are not interstellar grains. Carbon (graphite and diamond) and silicon carbide grains from the same meteorites also have large isotopic anomalies but these phases are not stable in the oxidized solar nebula which suggests that they are presolar and formed in the circumstellar atmospheres of carbon-rich stars. Diamond has a characteristic signature enriched in the lightest and heaviest isotopes of Xe, and graphite shows a wide range in C isotopic compositions. SiC commonly has C and N isotopic signatures which are characteristic of H-burning in the C-N-O cycle in low-mass stars. Heavier elements such as Si, Ti, Xe, Ba, and Nd, carry an isotopic signature of the s-process. A minor population of SiC (known as Grains X, ca. 1%) are distinct in having decay products of short lived isotopes 26Al (now 26Mg), 44Ti (now 44Ca), and 49V (now 49Ti), as well as 28Si excesses which are characteristic of supernova nucleosynthesis. The preservation of these isotopic anomalies allows the examination of detailed nucleosynthetic pathways in stars.
The Earth's age and early differentiation history are re-evaluated using updated isotopic constraints. From the most primitive terrestrial Pb isotopic compositions found at Isua Greenland, and the Pilbara of Western Australia, combined with precise geochronology of these localities, an age 4.49 +/- 0.02 Ga is obtained. This is interpreted as the mean age of core formation as U/Pb is fractionated due to sequestering of Pb into the Earth's core. The long-lived Rb-Sr isotopic system provides constraints on the time interval for the accretion of the Earth as Rb underwent significant depletion by volatile loss during accretion of the Earth or its precursor planetesimals. A primitive measured 87Sr/86Sr initial ratio of 0.700502 +/- 10 has been obtained for an early Archean (3.46 Ga) barite from the Pilbara Block of Western Australia. Using conservative models for the evolution of Rb/Sr in the early Archean mantle allows an estimate to be placed on the Earth's initial Sr ratio at approximately 4.50 Ga, of 0.69940 +/- 10. This is significantly higher than that measured for the Moon (0.69900 +/- 2) or in the achondrite, Angra dos Reis (0.69894 +/- 2) and for a Rb/Sr ratio of approximately 1/2 of chondrites corresponds to a mean age for accretion of the Earth of 4.48 + /- 0.04 Ga. The now extinct 146Sm-142Nd (T1/2(146)=103 l0(6)yrs) combined with the long-lived 147Sm-143Nd isotopic systematics can also be used to provide limits on the time of early differentiation of the Earth. High precision analyses of the oldest (3.8-3.9 Ga) Archean gneisses from Greenland (Amitsoq and Akilia gneisses), and Canada (Acasta gneiss) do not show measurable (> +/- l0ppm) variations of 142Nd, in contrast to the 33 ppm 142Nd excess reported for an Archean sample. The general lack of 142Nd variations, combined with the presence of highly positive epsilon 143 values (+4.0) at 3.9 Ga, indicates that the record of large-scale Sm/Nd fractionation events was not preserved in the early-Earth from 4.56 Ga to approximately 4.3 Ga. This is consistent with large-scale planetary re-homogenisation during ongoing accretion of the Earth. The lack of isotopic anomalies in short-lived decay systems, together with the Pb and Sr isotopic constraints is thus consistent with core formation and accretion of the Earth occurring over an approximately 100 Ma interval following the formation of meteorites at 4.56 Ga.
Our ideas about the origin and evolution of the solar system have advanced significantly as a result of the past 25 years of space exploration. Metal-sulfide-silicate partitioning seems to have been present in the early dust components of the solar nebula, prior to chondrule formation. The inner solar nebula was depleted in volatile elements by early solar activity. The early formation of the gas giant, Jupiter, affected the subsequent development of inner solar system and is responsible for the existence of the asteroid belt, and the small size of Mars. The Earth and the other terrestrial planets accreted in a gas-free environment, mostly from volatile-depleted planetesimals which were already differentiated into metallic cores and silicate mantles. The origin of the Moon by a single massive impact with a body larger than Mars explains the angular momentum, orbital characteristics and unique nature of the Earth-Moon system. The density and chemical differences between the Earth and Moon are accounted for by deriving the Moon from the mantle of the impactor.
Elemental analyses of the Ogueil Cl meteorite and all previous Cl chondrite analyses were employed to develop a new solar system abundance table, including the standard deviation and number of analyses for each element. The table also comprises the abundances of radioactive and radiogenic nuclides at the present and 4.55 AE ago, as well as abundances by weight in a typical Cl chondrite. The new abundances were within 20% of those determined by Cameron (1982), except for 14 cases in the range 20-50%, and 5 over 50%. The solar abundances were compared with the Cl abundances, showing a total of only 7 disagreements. No significant discrepancies were detected in the major cosmochemical groups, and a smooth trend was found in the abundances of odd-A nuclides. The new set is interpreted as accurate to 10%, with the Cl chondrites matching the primordial solar system abundances to at most 10% deviation.
Soldier crabs are challenging marine organisms to sample as they do not fit neatly into established faunal behavioural categories. Information on the soldier crab life cycle, ichnological products, and behaviour is a prerequisite to designing appropriate sampling, involving the consideration of the study objective (what to sample), temporal factors (when to sample), spatial factors (where to sample) and sampling method (how to sample). Largely infaunal for most of their life cycle, soldier crabs may be relatively sessile or quite vagile within the substrate, and epifaunal (emergent) for late stages of their life cycle. They also exhibit population partitioning, based on sex and size classes (when there are mixed cohorts); for example, it is mostly adult males that emerge in swarms, and mainly females and juveniles that remain in the subsurface. This behaviour has implications for studies of population dynamics that involve abundance, population structure, and sex ratios. To date, there has been emphasis on sampling while the crabs are emergent (forming so called "armies", or surface swarms), with the assumption that the whole population emerges. When infaunal and mobile, soldier crabs also present challenges to sampling in that they can vary in abundance laterally and vertically in a short time, and they can respond to prolonged sampling, or to researcher-induced perturbations during sampling, by burrowing downwards to avoid being collected (resulting in potentially spurious data with respect to their depth of occurrence and abundance). The complexity in behaviour of soldier crabs, the partitioning of populations, and the response to sampling have not been addressed to date by researchers elsewhere whereas it is an important component in the design of sampling methods.
Powderbark wandoo (Eucalyptus accedens) has a powdery triterpenoid-containing substance on the surface of its smooth bark, which is formed from sloughing peridermal cells. When compared with the similar-appearing wandoo (E. wandoo), which occurs in the same area and which does not accumulate powder, fewer bark-associated arthropods are found. Exposure tothis powder accelerated mortality of the ant, Iridomyrmex chasei, a species that tends scale and other sap-sucking insects on the foliage of eucalypts. Ants of this and two other species were unable to reach baits on the top of vertical wooden dowels that had been coated with powder taken from the bark of E. accedens. The powder may deter arthropods from living or moving on the bark by chemical or physical means. It is postulated that the function of the powder is to reduce the threat from herbivorous or scale-tending arthropods that may live on, or traverse, the bark of this species.
The arid-adapted Neobatrachus sutor and Pseudophryne occidentalis are most surface active immediately after heavy rain. The number of these frogs caught in pit-traps declined rapidly over a four day period after rain ceased. As we found no evidence of breeding, we concluded that N. sutor had come to the surface to feed, most probably on termites which we observed in very large numbers. We estimate the number of occasions that these two species of frogs could have been surface active, based on rainfall data, to be ≥ 9 and ≥ 17 yr-1 respectively.
Two recent captures and a sighting of Rankinia adelaidensis increase its recorded geographical distribution in a southerly direction. In accordance with other recent range extensions recorded south of the Swan River, it is probable that the geographical distributions for other species will be extended into the southern coastal plain with further surveys.
We examined the behavioural and spatial ecology of Lophognathus gilberti, a medium-sized, diurnal, dragon lizard that is commonly found in urban areas of north-western Australia. Males defend daily activity areas against other males, but not females. Both males and females shift their daily activity area on sequential days. Lophognathus gilberti use sight and perhaps auditory cues to locate prey, which consists mostly of invertebrates. They catch a prey item every 92 minutes, or 6-7 items each day, most often by sprinting from an elevated perch, but they do not actively search in leaf litter for prey. Three different stationary postures were observed; defensive, vigilant and aggressive. Males also have a courting posture that involves head bobbing, body pressing and tail twitching. These lizards often wave a forelimb and bob their heads after each short sprint. Movement is most often bipedal, with males moving greater distances (37.8 m h-1) than females (13 m h-1). When active, L. gilberti are most often found in full shade, and within 5 m of vegetation cover. They are constantly vigilant and are capable swimmers, diving to the bottom to avoid capture.
We investigated why the western bearded dragon (Pogona minor) is an early coloniser of rehabilitated waste dumps in the mining area around Ora Banda, Western Australia. The daily distance travelled for 19 (14 female and 5 male) P. minor, measured using nylon thread spools attached to the lizard's tail, was 115 m. This corresponded to a mean linear distance moved of 68 m. Our data suggest that P. minor are one of the first species of reptiles to colonise mine site rehabilitation areas because they move appreciably greater daily distances than other agamid lizards, are spatially widely-foraging, frequently forage in or use saltbush (Atriplex spp) and bluebush (Maireana spp) as basking sites, regularly traverse open areas, readily move up and down steep slopes, and eat bull ants which are generally present on rehabilitated sites. Pogona minor also have a high reproductive potential and show no obvious aversion to mine sites as oviposition locations. Pogona minor eggs incubated at 27 °C took an average of 64 days to hatch, the mean snout-to-vent length was 36.1 mm and the mean mass was 1.74 g.
A motor vehicle emission inventory is developed for the Perth metropolitan airshed by integrating data on traffic flow conditions with emission factors that incorporate the effects of both speed and acceleration. This highlights the impact of varying driving conditions on the spatial and temporal resolution of vehicle emissions, and illustrates that traffic congestion enhances pollutant production through increased variations in vehicle accelerations.
The south-west of Western Australia is a biodiversity hotspot and has a high proportion of endemic freshwater fishes. None of the native fish species are primary piscivores and with the exception of the freshwater cobbler (Tandanus bostocki) all species are small (< 200 mm total length (TL)). The introduction of non-native freshwater fish species is considered one of the most damaging threats to this region's native fish diversity. Recently a new, large (maximum size 300 mm total length) feral fish species, the South American Pearl Cichlid (Geophagus brasiliensis), was found in Bennett Brook, a small tributary of the Swan River. The aim of this study was to determine the salinity tolerance of the feral Pearl Cichlid in order to predict it's invasive potential in watercourses of the Swan River catchment. Geophagus brasiliensis tolerated direct transfer from fresh water to 18-27 PPT with no mortality but more importantly, G. brasiliensis was able to resist gradual transference from freshwater to salt water (36 PPT) with very low mortalities. Therefore, ongoing control efforts are required in order to limit/prevent the invasion of this feral species into the Swan and other catchments in the southwest of Western Australia.
The ant fauna in 33 Perth gardens was surveyed by hand collecting, and pitfall trapping. The resulting catch was considered at the species level and also four ant variables (abundance, species richness, species diversity and species evenness) were investigated for correlatlon wlth garden botanical and management variables. Forty-seven ant species from 22 genera were recorded from the gardens. Thirty-six species occurred in less than one third of the gardens which were studied. Some of the species were absent or uncommon in adjacent native vegetation indicating that they were favoured by urbanization while other species from the native vegetation were unable to colonize, or persist in, the gardens. Ant species richness and diversity were significantly lower in gardens than native vegetation while species evenness did not statistically differ between the two types of land use. The ant fauna was enhanced by the length of time the garden had been established, and also increased garden area, leaf litter and ground cover. Gardens where pesticides were used, where tall shrubs were dense or where management (e.g. watering) was intense, had a depauperate ant fauna. This study has indicated that urban gardens are an important refuge for ants and maybe, because ant species richness often reflects that of other invertebrates groups, for a wide range of other invertebrates.
The effect of bird predation on canopy arthropods inhabiting Marri (Eucalyptus calophylla) saplings was examined in Banksia woodland on the Swan Coastal Plain of Western Australia. Twenty pairs of saplings were selected and one of each pair was enclosed in bird-proof mesh to exclude foraging birds. Saplings were sampled in April 1998, prior to bird exclusion, and in August 1997, October 1997 and May 1998 after exclusion. Abundance, species richness and size of some arthropods increased on meshed saplings in certain months following bird exclusion. Spiders (Araneae) were most different between meshed and open saplings, with their abundance increasing on the saplings from which birds were excluded and remaining significantly more abundant after one year. The abundance of larger arthropods (in particular, spiders) increased and smaller animals decreased following bird exclusion, suggesting an interaction with birds on spiders as prey, and between spiders and their prey. Additional evidence of an effect of bird predation on the arthropod fauna was found in the amount of arthropod-related damage to leaves on meshed and open saplings. Damage to leaves, recorded over an 8-week period in spring, on meshed saplings was 21% of total leaf area, compared with 6% on open saplings. These differences indicate that damage to canopy foliage is reduced by bird predation of herbivorous arthropods, and are consistent with trends in arthropod abundances between open and meshed saplings. We conclude that predation by birds affects the composition and size structure of canopy arthropod communities on eucalypts, and there is merit in initiating longer and more extensive studies.
We report significant variation in reptile pit-trapping results for eleven survey periods over two and half years for nine sites in the Goldfields region of Western Australia. We collected a total of 51 species and 2868 individual reptiles from a surveying effort of 33264 pit-trap days. Year-to-year variation in relative abundances for particular species was greater than elsewhere reported as being the result of stochastic events such as fires. Seasonal variation in catch rates suggest that to adequately survey an area, pit-trapping programs need to be undertaken in more than one season. This has significant (financial) consequences for mining companies and other industries that employ consultants to undertake terrestrial fauna surveys to describe that component of the biodiversity for an area. Environmental protection agencies need to adjust their guidelines for terrestrial faunal surveys to adequately describe the biodiversity of an area. Our data indicate that before researchers can claim that year-to-year variation in reptile assemblages are due to stochastic events they must account for 'normal' year-to-year variations.
Although spatial variability in fauna assemblages has been discussed in the literature for many decades, terrestrial fauna surveys undertaken to support environmental impact assessments (EIAs) in Western Australia (WA) rarely adequately address this issue when undertaking surveys of the terrestrial vertebrate ecosystems. The specific objective of this investigation was to describe the spatial variability in the trapped terrestrial vertebrate fauna for five vegetation assemblages in the semi-arid northern goldfields region of WA. The trapped terrestrial vertebrate assemblage differed significantly among replicate sites in both the composition and relative abundance in each of the five habitats. A high proportion of species trapped were singletons and doubletons, and many species demonstrated a patchy distribution within habitats. Both of these parameters provide a strong case for addressing spatial diversity in terrestrial fauna surveys undertaken to support EIAs.
Previous work on assessing the errors in the Australian Height Datum (AHD) across Western Australia used fewer and older global positioning system (GPS) data and a global quasigeoid model. A larger and improved State-wide set of 243 GPS-derived ellipsoidal heights and a regional gravimetric quasigeoid model are now available. Therefore, it is possible to re-evaluate the north-south tilt in the AHD and look for regional systematic distortions with some more confidence in Western Australia. This new analysis shows an apparent north-south tilt of ~0.27 mm/km in the existing AHD over the whole of the State, but which increases to ~0.6 mm/km over smaller regions, showing regional systematic distortions. When mean sea-level constraints are removed from the AHD by a minimally constrained least-squares adjustment of the spirit-levelling observations that is less prone to the effect of sea-surface topography, the north-south tilt reduces to ~0.18 mm/km, but the regional distortions remain, showing that errors are present in the spirit-levelling observations.
Mictyris occidentalis, a new species of mictyrid crab (commonly known as soldier crab), is described from Western Australia. Diagnostic features include the macroscopically granular carapace; prominent granular ridges running posteriorly from the antero-lateral spines; front with broadly curved lateral lobes; rounded and projecting shape of the carapace posterior border and distinctly curved and setose dactyls on the 4th pair of walking legs. The new species combines characteristics of congeners M. longicarpus Latreille, 1806 and M. brevidactylus Stimpson, 1858 with which it is compared biometrically. M. occidentalis is the only Mictyris species extant from Shark Bay to Broome in Western Australia and is likely to be endemic. The taxonomic history of Mictyris species is summarised, and recognition of M. brevidactylus as a separate Asian species/ species complex and M. longicarpus as endemic to the eastern coast of Australia is supported. A key to the described species of Mictyris is provided.
Patches of exposed granite bedrock around Cue, in central Western Australia, that have been smoothed by being used for grinding are described and compared with portable grindstones recorded in the same region. Patches had rarely been reported from this area before, although they have long been recognised in the Pilbara. The extension into the southern half of Western Australia of a type of evidence for past human behaviour rarely identified there is significant. Two much-debated questions are also considered, but left unresolved due to insufficient data: whether there is a morphological difference between grindstones used to wet mill grass seeds and those used for dry grinding hard seeds and whether the juxtaposition of grinding, generally considered to have been women's work, with rock carvings, usually assumed to have been made by men, is socio-culturally significant.
The wetlands on the Becher Cuspate Foreland provide an opportunity to undertake palynological studies in a series of discrete small basins all belonging to the same wetland suite - the Becher Suite - from middle to late Holocene. The wetlands have formed progressively as the beachridge plain prograded westwards, and provide a landscape within a temporal framework wherein wetland initiation ranges from circa 4500 years in eastern locations to circa 900 years in western locations. Using patterns of surface pollen composition in relation to extant vegetation as a baseline the middle to late Holocene record was investigated in five wetlands, selected to incorporate different ages and plant/ vegetation assemblages. The five wetland basins, in relatively close proximity and in the same climatic setting, have markedly different pollen history reflecting intra-basinal evolution. Pollen content of the sediment to shallow depth suggests that the following vegetation assemblages will be useful to interpret past vegetation patterns: Centella asiatica (L.) Urb. herb assemblage, Baumea articulata (R. Br.) S. T. Blake sedge assemblage, Typha (L.) sp. sedge assemblage, mixed B. articulata and Typha sp. sedge assemblage, Melaleuca teretifolia Endl. scrub assemblage, M. rhaphiophylia Schauer forest/shrub assemblage, with understorey of C. asiatica, M viminea Lindley heath assemblage, M. cuticularis Labill. assemblage, and wetland margin of Xanthorrhoea preissii Endl., Isolepis nodosa (Rottb.) R. Br. and Sporobolus virginicus (L.) Kunth assemblages. Radiometric dating of the sediment cores was used to provide an age structure. Pollen diversity and abundance against this age structure indicated that, except for X. preissii and I. nodosa, most wetland species were present over the interval of 4500 years BP to the present in the middle to late Holocene. However, there were a number of other important patterns in the down profile abundance of wetland pollen taxa and their inter-basin variation at isochronous levels: a lack of continuity down profile for some species; fluctuations in numbers of pollen taxa that were continuous; lack of correlation in timing of the peak pollen numbers between separate basins; variable total composition at the same isochron level from wetland to wetland; variable total composition of wetland pollen at different ages within the same wetland; the association of pollen species with sediment types; increases and decreases of wetland margin pollen taxa in the down profile composition; and the recent appearance of I, nodosa and X. preissii within the last circa 1500 years. The patterns of pollen derived from wetland vegetation in individual wetlands suggest that the ancestral distribution and abundance of plant assemblages in the Becher wetlands was a function of intra-basin environmental changes caused by wetland evolution. In contrast, pollen derived from upland vegetation exhibited continuity down profile, suggesting that delivery of upland pollen has been largely consistent, though variable in abundance and composition from basin to basin, and being exogenic, it has not reflected (hydrochemical, edaphic or hydroperiod) environmental conditions within the wetlands. The combination of slow rates of sedimentation and bioturbation have obliterated any potential fine scale sequencing of pollen, resulting in a pollen record which may contain a composite of up to several hundred years of mixed wet and dry climate assemblages, making it difficult to interpret detailed climate history. However, the appearance of X. preissii and I. nodosa circa 1500 years ago, coupled with a corresponding change in stratigraphy, probably signals a recent increase in rainfall.
Mitochondrial DNA sequences were used to compare barramundi found in impounded parts of the Ord River system to their cultured counterparts from a fish farm in one dam (Lake Argyle). Two haplotypes were common to all fish sampled, indicating the high probability that farmed fish are escaping, and could potentially interact with the wild population of the lower Ord River. Although the Lake Argyle barramundi farm currently produces only about 50 tonnes of fish per year, there are plans to expand barramundi production at Lake Argyle by up to 200 times this amount. If that was to occur and no efforts were made to reduce the escape of cultured fish, then sufficient numbers of escaped barramundi may survive to reproduce in the wild fishery. Maintaining the genetic integrity of wild barramundi populations will be best achieved by setting and enforcing standards to minimise escapes from fish farms.
The imperfection of the fossil record was used by Charles Darwin to explain the lack of evidence for 'organs of extreme perfection and complication', which under his theory of natural selection must have evolved through a series of gradual transitions. In addition, a major premise in the theory of natural selection is that variation between organisms is required so selection for particular traits can occur. The fossil record has subsequently revealed a small number of sites comprising fossils of exceptional preservation including the Gogo Formation of Western Australia. Here a unique Late Devonian (Frasnian) reef fauna, with exceptional three-dimensional preservation of macrofossils combined with unprecedented soft-tissue preservation has preserved examples of the transitional forms and morphological variation Darwin predicted. The most significant discoveries have contributed: insights into reproductive biology, including the oldest known vertebrate embryos and evidence of sexual dimorphism with internal fertilization; the anatomy and variation present in the earliest gnathostomes, the placoderms, provides evidence of directional selection; some of the earliest morphological changes required in the transition from an aquatic to land environment are seen in the primitive tetrapodomorph, Gogonasus.
Gravimetric models of the geoid over Western Australia have been constructed using two adapted forms of Stokes's integral; one uses the unmodified Stokes kernel and the other uses a deterministically modified kernel. These solutions use a combination of the complete expansion of the EGM96 global geopotential model with Australian gravity and terrain data. The resulting combined solutions for the geoid are compared with the control given by Global Positioning System (GPS) and Australian Height Datum heights at 63 points over Western Australia. The improved fit of the model that uses a modification to Stokes's kernel indicates that this approach is more appropriate for gravimetric geoid computations over Western Australia.
The southwestern corner of the Australian continent has been identified as a global "biodiversity hotspot", defined as an area where "exceptional concentrations of endemic species are undergoing exceptional loss of habitat". In this paper we reconsider the reasons for this conservation priority. We briefly review significant characteristics of the flora and fauna, and the way threatening processes are escalating ecosystem stress to these conservation values. Our specific aim is to examine the ecological consequences of hydrological change, including emergent issues such as climate change, and focus on the coastal plains in higher rainfall zones where the majority of the Western Australian population resides. Here we argue that human-driven and/or climatically driven hydrological change deserve greater attention, since they: i) directly escalate the risk of extinction for some components of the biota, or ii) are underlying and/or contributing factors in the manifestation of other threats to the biota, and may complicate or exacerbate some of those threats (such as fire, Phytophthora and the spread of weeds). This paper briefly outlines the challenges to the region's biodiversity posed by hydrological change. We suggest a societal adoption of approaches based on water literacy will be necessary to avoid irreversible changes associated with a continued reliance on water resource developments and other energy/water intensive industrial activities.
Backfilled burrows belonging to Notomys alexis (Spinifex Hopping Mouse) were excavated in the Pilbara of Western Australia. The size and shape of one of these burrows is described, and it is postulated that the backfilling of burrows by the occupants is a protection strategy against predators such as large goannas and perhaps large snakes.
Recent captures of Nephrurus milii increase its recorded geographical distribution, suggesting the goldfields population extends further north than has previously been recorded and the Pilbara population is more widespread than has been earlier reported. The relative abundance of this species appears to differ appreciably across its range with the consequence that its presence could easily have gone undetected in the northern midwest and Murchison regions and other sections of the Pilbara due to a lack of adequate survey effort.
The greater bilby (Macrotis lagotis) is a conservation significant species because of a contraction in its geographic range and is now only found in a few locations in Australian sandy deserts and the Pilbara or Western Australia. We report on the presence of eight burrows and 605 diggings and scratchings in an area of about 9 ha for a small group of greater bilbies in the Pilbara. We describe burrows that were located adjacent to or under rocks, under an old termite mound and in mature spinifex. Most of the activity area, which had been burnt six months earlier, contained diggings and scratchings that we divided into three categories: nose cone diggings, scratchings and circular holes. Numerous scratchings contained the characteristic scats which can be used to identify the presence of greater bilby in an area. This paper provides information on the evidence that can be used to determine the presence of greater bilby in the Pilbara.
The Crest-tailed Mulgara (Dasycercus cristicauda), a species listed as vulnerable under the Commonwealth Environment Protection and Biodiversity Conservation Act (1999) and as a Schedule 1 species under the Western Australian Conservation Act (1950), was once found throughout and central Australia and Western Australia, but its geographic range has been significantly reduced. The spatial distribution and shape of Mulgara burrows is described for an area that was subsequently cleared in the Pilbara of Western Australia. The area contained a substantial cover (» 50% cover) of spinifex (Triodia sp.) tussocks to about 600 mm high and scattered shrubs when first searched in June 2006 but had been burnt (November 2006) by the time Mulgara were to be translocated before the vegetation was cleared in January 2007. Burrows contained between two and nine entrances, tunnels were mostly on a single level and to a depth of about 300 mm. The lumen for a burrow entrance was typically an arch over a flat bottom with a height of 70-80 mm, and a width of 80-100 mm at the base. Internal tunnels were mostly 50-70 mm wide. Burrows entrances in the burnt landscape were mostly in the open. There was one burrow per 2.5 ha in the area searched, but this was probably a 'hot-spot' for Mulgara for the region. Four Mulgara were caught in 750 Elliott trap-nights and five by digging out 65 recently active burrows in an area of about 22 ha. From this we concluded that a substantial trapping effort was required to trap all the Mulgara in an area. If Mulgara are being translocated from an area, then we would recommend an intensive trapping program combined with searching for and digging out all recently active burrows in the area. Strategies to enhance the capture of Mulgara are discussed.
Wet pitfall traps used to sample invertebrates, in particular, short-range endemic invertebrates for the purpose of supporting environmental impact assessments, killed, as by-catch, numerous small vertebrates. For the five surveys reported here, vertebrate by-catch rates varied between 0.4 and 15.6 individuals per 1000 trap nights using two litre plastic containers half-filled with ethylene glycol. No satisfactory alternative trapping strategy is available that provides quantitative data for sampling short-range endemic invertebrates (e.g., terrestrial molluscs, spiders and millipedes), which are a focus of the Western Australian Environmental Protection Authority. We discuss the trade-off between catching short-range endemic invertebrates as part of an environmental impact assessment against killing small vertebrates as by-catch. We urge government environmental regulators to provide greater clarity on the specific locations of where short-range endemic invertebrate surveys should be undertaken as an interim measure for reducing vertebrate trapping deaths until improved trapping protocols are available and to be more cautious when requiring surveys for short-range endemic invertebrates.
During fieldwork in the eastern goldfields, a gravid female thorny devil (Moloch horridus) was collected. Whilst held in captivity the female deposited eight eggs in a calico bag and apparently urinated over the clutch. We propose that thorny devils may hydrate their eggs after oviposition to reduce desiccation during development in the nesting burrow. This may lead to a fitness increase for the offspring at hatching in the form of increased hatchling size
This Special Issue of the Journal deals with the interactions between fires and wetlands, focusing on particular wetland soils and sediments of the Swan Coastal Plain bioregion that have a propensity to burn. In doing so, contributing authors cover the type of information required to understand those influences, like the nature of the soils and sediments themselves, the implications of the fires for environmental, social and economic values, and how the fires might be prevented.
The unconfined aquifers on the Swan Coastal Plain provide the population of Perth with much of its scheme water and the questionable effects of fire on the quality of surface and ground water, and recharge volumes, remain unanswered. In addition, recent concerns about fire in organic sediments and the effects of groundwater decline on acid sulphate soils have increased the need for research. Based mainly on a review of relevant literature, we formulate hypotheses as to the possible effects of fire on water quality in wetlands, particularly organic-rich ones, on the Swan Coastal Plain. Water quality responses may occur due to catchment effects (increased runoff and erosion, explainable by removal of canopy cover and changes in soil water repellency, resulting in nutrient and sediment fluxes into the wetland, elevated cation concentration and a shift to . alkalinity) and atmospheric effects (the return to the ground of dissolved volatilized reactive and particulate compounds). For both these effects, on the Swan Coastal Plain the over-riding catchment influences are the ways in which the wetlands interact with the shallow unconfined aquifers and how a fire and a changed fire regime might affect this relationship. Profound changes to water quality are possible upon rehydration of burnt or overheated (organic) soils. Cracking and erosion caused by fire can expose acid sulphate soils to oxidizing conditions, resulting in lower pH and mobilization of heavy metals. Superimposed on all these changes are the trophic consequences and how they might influence water quality. Finally we discuss the secondary effects that arise from management attempts to control or prevent fire in a wetland, such as fire suppression effects, flooding or trenching to stop a peat burn, or prescription burning around a wetland to reduce fuel loadings, each of which might trigger or exacerbate any of the above mentioned water quality responses. Management should therefore apply a precautionary approach to prevent irreversible losses (like erosion of organic soil profiles) and otherwise use an adaptive management approach to test the hypotheses stated herein.
Endurance of juvenile Western Australian varanid lizards was compared with that of conspecific adults. Among adults, endurance generally increased intra-specifically with increasing body size. However, juvenile varanids have a higher than expected endurance. Possible causes for this heightened endurance are discussed, and probably result from a relatively high maximal metabolic rate, as has been previously described for juvenile varanids. Origins of relatively high metabolic rates are unknown, but may be caused by greater oxygen affinity of juvenile haemoglobin when compared to adult conspecifics.
The process of evolution underpins all in biology, directs research and provides a unifying explanation for the history and diversity of life. The study of evolutionary biology draws on many disciplines (from molecular biology to ecology to palaeontology), and has applications in numerous areas, such as medicine, conservation, and agriculture. How then do we use evolution to train university undergraduates in a meaningful way, and what do we want them to learn? There are many aspects of evolution that could be taught at the undergraduate level, and content will vary depending on the course-context. Some basic components include the evidence for evolution, microevolution, speciation and macroevolution. However, teaching evolution offers exciting opportunities to convey more than just content. Evolutionary biology immerses students in the process of science and should encourage them to think critically and to carefully analyse concepts, problems and evidence. It offers students nearing graduation the opportunity to draw together their learning across different areas in biology, asking them to synthesize their thinking and appreciate how problems in evolution can be analysed with multidisciplinary tools. In this paper we argue the importance of teaching evolution and justify its place in the teaching curriculum by providing examples of its wide applications, and by using case studies to illustrate the value of inquiry learning in teaching evolution at all undergraduate levels.
In Western Australia, peat is distributed throughout the Swan Coastal Plain, in the South West and North West regions of the State. Peat is typically associated with wetlands and its distribution has significantly reduced over the past 100 years. The major threats to the current distribution of peat are fire and land use changes. Peat is thought to be at increased risk of fire in particular due to the proximity of residential development and the drying period being experienced in South Western Australia. Peat, largely arising from accumulated plant matter, burns very easily when dry and fire in these systems is often very hard to extinguish due to the depth of material. Peat smoke is made up of a complex mixture of water vapour, gases and fine particles. In general, peat smoke is characterized by high concentrations of organic carbon, elemental carbon, and potassium. The gases in peat smoke include carbon monoxide, carbon dioxide, nitrogen oxides, sulfur oxides, carbonyl compounds, polycyclic aromatic hydrocarbons and other irritant and hazardous volatile organic compounds. All of these have been shown to cause deleterious physiologic responses at high concentrations in laboratory studies of animals and a limited number of chamber studies of humans at lower concentrations. There is little known about the health effects of exposure to peat smoke as few studies have focused specifically on this potential source of air pollution. Information is, however, available on the composition of peat smoke and there are some studies arising from specific fires which resulted from burning of underground environments, including events in Russia, USA and Indonesia. Peat smoke therefore represents a concern for communities living in areas where there is an increased risk of fire and where duration of fire in these systems is lengthy. This paper presents a review of information available on adverse health effects, notably respiratory diseases and symptoms, associated with components of peat smoke. The health effects reported from epidemiological studies from which exposure to peat fires has been referenced is also reviewed, along with a summary of some of the literature on exposures to bushfire smoke which shares similar components to peat smoke.
The threatened Western Ringtail Possum (Pseudocheirus occidentalis) is relatively abundant in numerous locations on the coastal strip between Bunbury and Dunsborough, Western Australia. But this area is subject to rapid residential development and there is the inevitable conflict between protecting a threatened species and development. We recorded 306 dreys, mostly in Peppermint trees, in the Dunsborough town site. Areas with high concentrations of dreys did not necessarily coincide with where most possums were found foraging. Over six nights 118 P. occidentalis were seen in road side verges, 246 in remnant vegetation and 53 in residential areas, indicating that they are abundant in this highly disturbed habitat. We use these data to discuss potential management options (i.e., no development, do nothing, translocate or in-situ management) for new development sites in the region.
At Mileura Station, Western Australia, the low rainfall is concentrated into the creek systems. Regular plant production takes place in the creeks so that annuals and perennials both show seasonality to which the animals' life cycles appear to be geared. In years of heavy rainfall the whole land surface is productive and animals breed abundantly. In years of low rainfall only enough plant food is produced to enable animals to survive and few or none breed. Animal populations survive in the region by a capacity for nomadism or an ability for a few individuals to survive in favoured sites during dry times coupled with an ability to reproduce rapidly when conditions are good. In addition to physiological and behavioural adaptations to the arid conditions, examples are presented to suggest that the longevity of animals is determined by the frequency with which years occur when breeding and recruitment are successful. Populations in which no individuals can live long enough to survive from one productive season to the next will soon be eliminated. -from Author
In the flora of south-western Australia, vegetative colour change in summer and autumn followed by regreening after rain is much more widespread than previously reported, though patchy in occurrence and variable within species. The term diallagy (adj. diallagous) is proposed to describe the strategy of reversible change between the green and coloured states. It is here recorded for 99 species in 59 genera of 24 families of flowering plants, both monocots and dicots. These species occur in a number of widely distributed habitats. In some species, extent of colour change increases as long as the dry weather continues. The change generally is reversed after 10-15 mm or more of rain falls over a short period (24 hours). Regreening takes from several days to several weeks. The mechanisms operating within the plants are yet to be investigated, but possibilities are discussed to point the way to further research; some are likely to be similar to that reported for Borya. In an extreme dry summer such as that of 2000-2001, death occurs in some species. Paradoxically, other species flower at this season, in some cases close to diallagous species. It is suggested that these have retained a summer/autumn flowering period (from a tropical origin) to take advantage of pollinators at a season when few sources of nectar and pollen are available.
One is a version of Neumanns' CLIPER adapted for the region and referred to as CPLR, another is a method developed in Western Australia which uses the low-level relatively vorticity field in the environment of the cyclone as a predictor, and the last is pure persistence. The three methods were used to produce 214 triplets of forecasts from best-track data for 13 cyclones and the results compared. The Wilcoxon test was used to test the significance of differences between forecasts for various subsets of cyclones. The results suggest that a) the performances of the first two methods match that of persistence overall, and are superior when the error in the persistence forecast is greater than the mean error or when the cyclones are recurving, and b) the second method matches CPLR overall and surpasses it with some categories of cyclones. -from Authors
In the Western Australian wheatbelt, small intact remnants of bushland can contribute significantly to overall biodiversity. Our comprehensive vascular flora survey of Nature Reserve A21064, a reserve of 110 hectares near the town of Arthur River, has highlighted this aspect. Comprehensive surveys of selective wheatbelt reserves provide benchmarks to help us better understand the flora and vegetation in this highly cleared and fragmented agricultural landscape. In the diverse flora of this relatively undisturbed upland remnant ten distinct plant communities encompassing heaths, herbfields, mallee and woodlands can be recognised. The survey identified 323 vascular plant taxa including one rare species, seven priority species and a number of taxa of special interest recorded from 51 families. Weeds accounted for 22 species (6.8% of total flora), however, the extent of invasion is relatively low.
Granite domes provided Aboriginal people living on the surrounding plains with a variety of economic products. Granite domes also acted as focal points for the activities of ancestral heroes who journeyed throughout the landscape. Aboriginal religious practice includes ritual dramas which replicate the activities of these ancestral heroes at such sites. Surface geology therefore determines both the economic practices and religious activities undertaken by Aboriginal people within their territories.
This paper outlines descriptions of colour in the literature pertaining to the flora of the South-western Australian Floristic Region, comparing pre-settlement exploration by Dutch, French and English voyagers with modern general texts. It was found that colour has been and continues to be poorly described, preventing any analysis of the biological diversity of colour to enable comparison across or between floras or species. Forthcoming work on more accurate colour description using the Natural Color System of Sweden is foreshadowed.
The influence of the Leeuwin Current on the marine flora of the Houtman Abrolhos is examined. The marine plants (seaweeds and seagrasses) are assessed by comparisons of the Houtman Abrolhos species diversity and composition relative to a nearby coastal region (Jurien Bay), using the tropical and temperate floras of Western Australia as benchmarks. Our results demonstrate that, in terms of assemblage structure and taxonomic distinctness, the marine flora of the Houtman Abrolhos clearly represent a transitional zone between tropical and temperate regions, with the strong tropical influence a direct result of the Leeuwin Current. In contrast, the nearby inshore flora of the Jurien Bay region exhibits a much lower, almost negligible tropical Influence.
The Houtman Abrolhos reefs comprise three carbonate platforms situated between latitudes 28° and 29.5°S on the western continental margin of Australia, close to the present southerly limit for coral growth. The geomorphology of the platforms and their low islands varies from atoll-like in the south to less regular forms in the north. "Blue-hole' terrains are conspicuous elements of the eastern parts of the platforms. Lagoon sand sheets are dominated by corals and calcareous red algae, in contrast to shelf sediments which are composed of bryozoans, calcareous red algae, molluscs and foraminifers. The coral reefs of the Abrolhos platforms have a probable maximum thickness of 130m, and postdate open carbonate shelves of Paleocene to Upper Eocene age. The growth history of the Abrolhos over the last few hundred thousand years is closely linked to global sea level fluctuations. Late Quaternary stratigraphy exposed in platform islands is dominated by coral-algal framestone/bindstone and rudstone, for which preliminary dates suggest a Last Interglacial age (c125 ka BP). Late Holocene coral reef development is largely restricted to leeward reef slopes, walls of "blue-holes', and leeward, more easterly surfaces of platforms. The persistence of reef growth during the Quaternary is linked to the presence of the Leeuwin Current, which probably only came into existence during the Early to Middle Pleistocene. -from Authors
Lack of upwelling, and low marine productivity, results in seabirds being much less abundant off Western Australia than along the coasts of W South America and SW Africa. The breeding and non-breeding distributions of seabirds appear to be influenced by the presence of the Leeuwin Current, as do the timing and success of their breeding activity. For instance, in a year of strong Leeuwin Current flow, little penguins Eudyptula minor near Perth carried less food, were in poorer condition and laid eggs much later than in a year of weaker flow. -Authors