Arid Regions Of Australia Research Articles

Batrachochytrium dendrobatidis in the Arid and Thermally Extreme Sonoran Desert.

Batrachochytrium dendrobatidis (Bd), the causative agent of the devastating global amphibian disease chytridiomycosis, was not projected to threaten amphibians in hot and arid regions due to its sensitivity to heat and desiccation. However, Bd is being detected more frequently than ever in hot and arid regions of Australia and the USA, challenging our current understanding of the environmental tolerances of the pathogen under natural conditions. We surveyed for Bd in an extremely hot and arid portion of the Sonoran Desert, where the pathogen is not projected to occur, and related presence and prevalence of the pathogen to local environmental conditions. We collected eDNA samples from isolated desert water sites including six tinajas and 13 catchments in June and August of 2020 and swabbed a total of 281 anurans of three species (red-spotted toad Anaxyrus punctatus, Couch's spadefoot Scaphiopus couchii, and the Sonoran Desert toad Incillius alvarius) across five catchments and six tinajas from June to September of 2020. Overall, Bd occurred at 68.4% of sites, despite extreme heat and aridity routinely exceeding tolerances established in laboratory studies. Average summer maximum air and water temperatures were 40.7°C and 30.7°C, respectively, and sites received an average of just 16.9mm of precipitation throughout the summer monsoon season. Prevalence was low (5.7%) across species and life stage. Our results demonstrate that Bd is capable of persisting and infecting amphibians beyond its projected range, indicating a need to account for higher thermal tolerances when quantifying risk of Bd presence and infection.

Phytochemistry, Medicinal Properties, Bioactive Compounds, and Therapeutic Potential of the Genus Eremophila (Scrophulariaceae).

The genus Eremophila (family Scrophulariaceae) consists of approximately 200 species that are widely distributed in the semi-arid and arid regions of Australia. Multiple Eremophila spp. are used as traditional medicines by the First Australians in the areas in which they grow. They are used for their antibacterial, antifungal, antiviral, antioxidant, anti-diabetic, anti-inflammatory, and cardiac properties. Many species of this genus are beneficial against several diseases and ailments. The antibacterial properties of the genus have been relatively well studied, with several important compounds identified and their mechanisms studied. In particular, Eremophila spp. are rich in terpenoids, and the antimicrobial bioactivities of many of these compounds have already been confirmed. The therapeutic properties of Eremophila spp. preparations and purified compounds have received substantially less attention, and much study is required to validate the traditional uses and to highlight species that warrant further investigation as drug leads. The aim of this study is to review and summarise the research into the medicinal properties, therapeutic mechanisms, and phytochemistry of Eremophila spp., with the aim of focussing future studies into the therapeutic potential of this important genus.

Historical and future climate change fosters expansion of Australian harvester termites, Drepanotermes.

Past evolutionary adaptations to Australia's aridification can help us to understand the potential responses of species in the face of global climate change. Here, we focus on the Australian-endemic genus Drepanotermes, also known as Australian harvester termites, which are mainly found in semiarid and arid regions of Australia. We used species delineation, phylogenetic inference, and ancestral state reconstruction to investigate the evolution of mound-building in Drepanotermes and in relation to reconstructed past climatic conditions. Our findings suggest that mound-building evolved several times independently in Drepanotermes, apparently facilitating expansions into tropical and mesic regions of Australia. The phylogenetic signal of bioclimatic variables, especially limiting environmental factors (e.g., precipitation of the warmest quarter), suggests that the climate exerts a strong selective pressure. Finally, we used environmental niche modeling to predict the present and future habitat suitability for eight Drepanotermes species. Abiotic factors such as annual temperature contributed disproportionately to calibrations, while the inclusion of biotic factors such as predators and vegetation cover improved ecological niche models in some species. A comparison between present and future habitat suitability under two different emission scenarios revealed continued suitability of current ranges as well as substantial habitat gains for most studied species. Human-mediated climate change occurs more quickly than these termites can disperse into newly suitable habitat; however, their role in stabilizing arid ecosystems may allow them to mitigate effects on some other organisms at a local level.

Drylands face potential threat of robust drought in the CMIP6 SSPs scenarios

In an increasingly globalized and warming world, drought can have devastating impacts on regional agriculture, water resources, and the ecological environment. Reliable prediction of future drought changes is especially important within the context of rapid warming. However, the extent and future trends of drought changes are variable and incomplete in the CMIP6 forcing scenarios. Based on the CMIP6 data, we chose the standardized precipitation-evapotranspiration index to predict future global drought. The results show that when emissions increase under the three shared socioeconomic pathway (SSP) scenarios (SSP126, SSP245 and SSP585), the global climate environment becomes drier and drought grow more severe and longer-lasting. Regions already classified as arid will suffer even more severe drought under high-emission SSPs. Specifically, 36.2% of global land will experience increased drought under SSP126, including 67.0% of regions designated as arid, with droughts intensifying significantly. Under SSP585, 68.3% of global land will suffer increased drought, with 93.2% of the arid regions experiencing significant drought intensification. Furthermore, the global duration of drought is estimated to be 4.4 months, 5.7 months, and 8.6 months for the time periods 1960–2000, 2021–2060, and 2061–2100, respectively. Notably, for the SSP585 scenario, regions that are already arid may become universally drought-stricken by the late 21st century. The most severe aridification trends may occur in the arid regions of Australia, Middle East, South Africa, Amazon basin, North Africa, Europe, and Central Asia. Additionally, Europe and the Amazon River Basin are also facing the threat of future drought. Increased aridification will put these regions and countries at risk of further land and ecological degradation, as well as increased poverty. The results of this study have far-ranging implications not only for how we deal with the impacts of climate warming-induced drought disaster, but also for how these impacts affect socio-economic and ecological security.

Detection and Establishment of Aedes notoscriptus (Diptera: Culicidae) Mosquitoes in Southern California, United States.

Aedes notoscriptus (Skuse), the Australian backyard mosquito, is a pestiferous daytime-biting species native to Australia and the surrounding southwestern Pacific region. It is suspected to play a role in the transmission of several arboviruses and is considered a competent vector of dog heartworm, Dirofilaria immitis (Leidy). This highly adaptable mosquito thrives in natural and artificial water-holding containers in both forested and urbanized areas, from tropical to temperate climates, and has benefitted from a close association with humans, increasing in abundance within its native range. It invaded and successfully established in New Zealand as well as in previously unoccupied temperate and arid regions of Australia. Ae. notoscriptus was discovered in Los Angeles County, CA, in 2014, marking the first time this species had been found outside the southwestern Pacific region. By the end of 2019, immature and adult mosquitoes had been collected from 364 unique locations within 44 cities spanning three southern California counties. The discovery, establishment, and rapid spread of this species in urban areas may signal the global movement and advent of a new invasive container-inhabiting species. The biting nuisance, public health, and veterinary health implications associated with the invasion of southern California by this mosquito are discussed.

An instance of parasitism on a human by a nymph of the kangaroo soft tick, Ornithodoros gurneyi Warburton, 1926 (Acari: Argasidae) in South Australia

The kangaroo soft tick, Ornithodoros gurneyi Warburton, 1926, is a poorly studied argasid of the more arid regions of Australia. Anecdotal accounts have stated that this tick species will bite humans, and yet bites have not been described. Herein we report on an instance of parasitism by a nymph of O. gurneyi on a human, and we provide a summary of confirmed instances of parasitism on humans by this tick based on museum specimens.

Description of two new Australian species of Abantiades Herrich-Schäffer (Lepidoptera: Hepialidae) and females of two further species with notes on their biogeography.

Abantiades cephalocorvus sp. nov. and Abantiades tembyi sp. nov. are described, along with the previously undescribed females of A. macropusinsulariae Simonsen, 2018 and A. pallida Simonsen, 2018. All of these species belong to a triforked Abantiades Herrich-Schäffer clade that is loosely centred around the Nullarbor and other arid regions of Australia. We explore DNA barcodes (mtDNA COI gene) from these and other Abantiades and discuss their significance for species recognition. The species distributions are entirely or largely allopatric and we discuss their origins from a widespread common ancestor that was likely distributed over inland and coastal regions in the mid- to late-Mesozoic before the onset of desertification. Notes on new distributional data for all of the known species in this clade are included.

A new species of Mouse Spider (Actinopodidae, Missulena) from the Goldfields region of Western Australia

A new species of Mouse Spider (family Actinopodidae Simon, 1892), Missulena harewoodi, is described from near the City of Kalgoorlie-Boulder in the Goldfields region of Western Australia. It differs from all other Missulena species by the unusual light grey colouration of the abdomen in combination with small body size and shiny carapace. A phylogenetic analysis of a fragment (658 bp) of the COI barcoding gene places M. harewoodi sp. n. in a clade with four Missulena species from the Pilbara region of Western Australia, more than 900 km away. Missulena harewoodi sp. n. is one of the many species in this genus that are currently only known from a single, or a very limited number of specimen, highlighting the paucity of fauna collections in many arid regions of Australia and the difficulties in sampling these cryptic spiders.

Movement patterns of three species of sparrow in the central Monte desert, Argentina: differences between and within species

Accurate knowledge of the movements of passerine populations in the southern hemisphere is difficult to attain, in part owing to differences in movements between and within species and between and within populations. In temperate South America, descriptions of patterns of movements are often based on reports of local changes in abundance and occurrence of species and there have been few detailed studies of movements at the local population level. We banded and monitored individuals of three species of sparrow -the Many-coloured Chaco-Finch (Saltatricula multicolor), Ringed Warbling-Finch (Poospiza torquata) and Rufous-collared Sparrow (Zonotrichia capensis) in a temperate site in the central Monte desert, Argentina, to evaluate differences in site-attachment between and within species. We found resident populations of all three species, the juveniles of which showed little site-attachment. We also observed a large influx of mobile Ringed Warbling-Finches and Rufous-collared Sparrows during the non-breeding season. We confirmed population partial migration of two subspecies of Rufous-collared Sparrows (and, possibly, a third otherwise resident subspecies), and possibly also within Ringed Warbling-Finches. The influxes of mobile individuals during the non-breeding season may be in response to unpredictable climate and consequent availability of resources, as has been found in arid regions of Australia and Africa. Our results provide a basis for a better understanding of the evolution of movement patterns of birds in temperate South America.

Rainwater utilization from roof catchments in arid regions: A case study for Australia

Water is a scarce resource in arid regions, and hence water harvesting is critically important in these regions for which many different means are adopted including groundwater and rainwater harvesting. This paper examines the feasibility of rainwater harvesting from roof catchments in arid regions of Australia. For this, ten representative locations in the arid regions of Australia are selected. Also, ten different sizes of rainwater tanks ranging from 5 kL to 50 kL and three different combinations of water uses are considered. A model is developed to simulate the performance of a rainwater harvesting (RWH) system. It is found that the reliability of a RWH system is highly dependent on mean annual rainfall at the location of interest. It is found that a 20 kL tank can provide a reliability of 61%–97% for toilet and laundry use depending on the location within the Australian arid regions. At the current water price, RWH system is not financially viable in the Australian arid regions. The methodology adopted in this paper can be adapted to other similar arid regions of the world.

Aridification drove repeated episodes of diversification between Australian biomes: Evidence from a multi-locus phylogeny of Australian toadlets (Uperoleia: Myobatrachidae)

Australia is a large and complex landmass that comprises diverse biomes ranging from tropical rainforests to harsh deserts. While Australian biotic diversity has evolved in response to landscape and climate changes, evidence of Miocene or later biome shifts are few. The Australo-Papuan endemic frog genus Uperoleia is widely distributed across mesic, monsoonal tropic and arid regions of Australia. Thus, it represents an ideal system to evaluate biome shifts as they relate to known landscape and climate history. We comprehensively sampled the distributional range of 25 described Uperoleia species and generated a detailed molecular phylogeny for the genus based on one mitochondrial and five nuclear loci. Our results support a single origin of monsoonal tropic taxa, followed by diversification within the region under the influence of the Australian monsoon. Molecular dating analyses suggest the major divergence between eastern mesic and monsoonal species occurred in the Miocene approximately 17million years ago, with repeated evolution of species from monsoonal biomes to arid or mesic biomes in the later Miocene, early Pliocene and at the beginning of the Pleistocene. Our detailed sampling helps to clarify the true distributions of species and contributes to on-going work to improve the taxonomy of the genus. Topological differences between nuclear and mitochondrial phylogenies within major clades suggest a history of mitochondrial introgression and capture, and reduce the ability to resolve close interspecific relationships.

Proximate causes and possible adaptive functions of mast seeding and barren flower shows in spinifex grasses (Triodia spp.) in arid regions of Australia

Mast seeding, the intermittent production of large synchronised seed crops among plant populations, is a phenomenon that occurs at exceptionally long intervals in spinifex grasses (Triodia spp.) from arid regions of Australia. This is despite the reliance of these fire-sensitive plants on seeds for post-fire regeneration, and that spinifex grasslands rate among Australia’s most flammable ecosystems. The proximate causes and possible adaptive functions of masting in seven species of spinifex from arid regions within the 350-mm rainfall isohyet were investigated. Specifically, the seed set percentages of 79 specimens collected between 1947 and 2012 were related to the following environmental covariates: antecedent rainfall over 6, 12 and 36 months, relative humidity, and the number of days above 40°C and below 0°C during anthesis. Given the potential importance of seeding events for post-fire regeneration, it was also investigated whether masting in Triodia could represent a fire-related form of environmentally predictive masting, by testing whether high-yield years corresponded to years of increased fire occurrence. Examination of the dataset showed that 43% of specimens contained completely aborted inflorescences (0% seed fill), while seed set ranged from 2 to 69% in the remaining specimens. High levels of insect activity were also found, with 42% of specimens showing evidence of insect occupation. Statistical analyses showed that the main environmental driver of seed set was high precipitation over the previous 12 months, and that high-yield years were strongly related to years of increased fire likelihood. The number of days over 40°C was a weakly significant driver of yield, while the remaining covariates were not significant. It is hypothesised that intermittent reproduction by Triodia is a fire-related form of environmentally predictive masting, which maximises chances of post-fire regeneration by satiating seed predators during flammable periods (i.e. after heavy rain years). Furthermore, it is suggested that non-viable flower crops after initial low rainfalls may have an adaptive function, by diluting pre-dispersal seed predator densities with ‘decoy’ ovules that do not mature and lead to the starvation of developing larvae.

Habitat use and ecological observations of the Ooldea dunnart (Sminthopsis ooldea) at Uluru–Kata Tjuta National Park, Northern Territory

The Ooldea dunnart (Sminthopsis ooldea) is a small (10–11 g) and poorly known dasyurid marsupial that is endemic to the central and western arid regions of Australia. Surveys carried out at Uluru–Kata Tjuta National Park, Northern Territory, from 1994 to 2010 yielded 37 captures of this elusive species, providing novel insights into its biology. Most captures were made in pitfall traps, with spring breeding confirmed by the presence of pregnant or lactating females during October and November. Animals were captured in mallee and mulga woodland and spinifex (Triodia spp.) dominated dune fields and sand plains. Capture rates were variable in most habitat types, but were relatively consistent in one site dominated by mulga (Acacia aneura). Although we found no consistent association between captures of S. ooldea and prior rainfall, fewest animals were captured in the two wettest years of the study. Ooldea dunnarts showed no clear response to fire. We suggest that mulga is a key habitat for S. ooldea, but also that the demography of this species may be shaped by biotic and/or abiotic factors that remain to be fully elucidated.

Regional flood frequency analysis in arid regions: A case study for Australia

Summary A large part of the world faces the problem of aridity, e.g. in Australia, the semi-arid and arid regions occupy about 50–75% of the country. There is a serious lack of data on many key hydrological processes in the arid regions, which makes it difficult to understand the hydrological processes in these regions. Although arid regions are characterised by a very low mean annual rainfall, it can experience severe flooding causing widespread damage. In hydrological literature, there is a limited presence of the application of regional flood frequency analysis (RFFA) studies for the world arid regions due to limited data availability. This paper presents a RFFA study for the semi-arid and arid regions of Australia using the most up-to-date data set and compares the results with that of the world data. It has been found that arid catchments exhibit a higher loss and lower runoff coefficient values as expected. Based on four model selection criteria and L -moments ratio diagram, it has been found that a Generalised Pareto distribution is preferable to the Exponential distribution to fit the partial duration series flood data in the arid regions of Australia. It has also been found that the arid region exhibits much steeper flood frequency growth curve than that of the humid region and the growth curve gets steeper with the decreasing mean annual rainfall. The developed growth curve for the semi-arid and arid region of Australia is found to be similar to other typical semi-arid and arid regions of the world. The developed prediction equation for the mean annual flood in the semi-arid and arid region of Australia uses two readily obtainable predictor variables (catchment area and design rainfall intensity), which can be used along with the developed growth curve to estimate design floods for the ungauged catchments in these regions with reasonable accuracy. The growth curve developed in this study is primarily applicable to the semi-arid and arid regions of Australia; however, this may be adapted to other similar regions of the world along with the locally developed prediction equation for the scaling factor (i.e. mean annual flood in this case) to derive preliminary design flood estimates.

Biogeography of Nicotiana section Suaveolentes (Solanaceae) reveals geographical tracks in arid Australia

Aim Nicotiana section Suaveolentes is largely endemic to Australia but includes one species endemic to Africa, one to New Caledonia and Tongatupa, and one to the Marquesas Islands in the Pacific. Other sections of Nicotiana are found in the New World. In Australia, Suaveolentes is widespread across the continent, with many taxa adapted to the Eremean zone. We aim to analyse the biogeography of the Australian clade, both to shed light on the evolution of the group and to determine general area relationships that provide insight into the history of the arid-zone biota. Location Mesic and arid regions of continental Australia, the Central–South Pacific and Namibia, Africa. Methods A phylogeny of Suaveolentes, based on morphology and molecular data, was used to analyse the relationships of areas in which the taxa occur. The section is monophyletic, and all but three taxa were included (25). The method of paralogy-free subtree analysis was employed, with the basal taxon Nicotiana africana used as the outgroup. Results Paralogy-free subtree analysis found five area subtrees that, when combined, resulted in a minimal area cladogram with six resolved nodes. Pacific and mesic eastern Australia (including Lord Howe Island) are at the base of the area cladogram, followed by the differentiation of North West Australia and later South East Australia. Arid regions of Australia are related, revealing three biogeographical tracks: a northern track including the Great Sandy Desert and Tanami, which are related to the Pilbara; a central track relating the Western Desert, Central Ranges, Eastern Desert and North East Interzone; and a southern track relating the South West Interzone, Nullarbor, Adelaide/Eyre and the South East Interzone. Plesiomorphic taxa with chromosome number n = 24–23 occur on the periphery of the continent, and derived taxa with n = 21, 20, 18, 16–15 identify the tracks across arid Australia. Main conclusions The patterns of distribution and differentiation of Suaveolentes in Australia show that the age of the clade is at least Early Miocene, dating to before the onset of aridification in Australia about 15 Ma. The patterns are also interpreted as evidence that it was vicariance that largely shaped speciation in the Eremean zone, with range expansion of some widespread taxa probably occurring in the most recent cycles of severe drying and mobilization of desert dune sands.

Creating an Integrated Historical Record of Extreme Particulate Air Pollution Events in Australian Cities from 1994 to 2007

ABSTRACT Epidemiological studies of exposure to vegetation fire smoke are often limited by the availability of accurate exposure data. This paper describes a systematic framework for retrospectively identifying the cause of air pollution events to facilitate a long, multicenter analysis of the public health effects of vegetation fire smoke pollution in Australia. Pollution events were statistically defined as any day at or above the 95th percentile of the 24-hr average concentration of particulate matter (PM). These were identified for six cities from three distinct ecoclimatic regions of Australia. The dates of each event were then crosschecked against a range of information sources, including online newspaper archives, government and research agency records, satellite imagery, and aerosol optical thickness measures to identify the cause for the excess particulate pollution. Pollution events occurred most frequently during summer for cities in sub-tropical and arid regions and during winter for cities in temperate regions. A cause for high PM on 67% of days examined in the city of Sydney was found, and 94% of these could be attributed to landscape fire smoke. Results were similar for cities in other subtropical and arid locations. Identification of the cause of pollution events was much lower in colder temperate regions where fire activity is less frequent. Bushfires were the most frequent cause of extreme pollution events in cities located in subtropical and arid regions of Australia. Although identification of pollution episodes was greatly improved by the use of multiple sources of information, satellite imagery was the most useful tool for identifying bushfire smoke pollution events. IMPLICATIONS Landscape fire smoke is an episodic and increasingly important environmental hazard for human populations. However, the health effects attributable to landscape fire smoke remain uncertain, partially because of the challenges associated with exposure assessment. This paper describes a systematic framework for retrospectively identifying the cause of air pollution events to facilitate a long, multicenter analysis of the public health effects of vegetation fire smoke pollution in Australia.

Distribution and speciation of gold in biogenic and abiogenic calcium carbonates – Implications for the formation of gold anomalous calcrete

Calcrete (pedogenic Ca carbonate) is an important sampling medium for geochemical gold (Au) exploration in semi-arid and arid regions of Australia, because it is widespread, easy to sample and calcium (Ca) shows a strong positive correlation with Au, but not with base metals, in calcrete overlying buried Au mineralization. In this study we show that the formation of Au-anomalous calcrete can be biomediated through the activity of resident microorganisms, and may not simply be the result of passive nucleation on inactive cells or evapotransporative processes. Calcified microfossils are highly abundant in calcrete from the Barns Au-prospect in South Australia. These microfossils are morphological analogues of calcified cells and biofilms formed in laboratory experiments conducted with active bacterial cultures enriched from Au-anomalous calcareous sand from the Barns prospect. Calcium carbonates precipitated by these cultures consisted mostly of calcite, which is the main carbonate mineral in calcrete. Synchrotron micro-X-ray fluorescence (S-μXRF) mapping was used to assess the distribution of Au, Zn, Ca and other metals in Ca carbonates precipitated by active bacterial cultures. On a μm-scale the distribution of Au was heterogeneous in these Ca carbonates and differed from base metal distribution, thus mimicking the spatial separation of these metals observed in calcrete. The speciation of Au in Ca carbonates precipitated by active bacteria was measured using micro-X-ray absorption near edge structure spectroscopy (μ-XANES) and resembled that observed in Au-anomalous calcrete closely. While metallic Au was observed in Au ‘hotpots’, ionic Au was detected in the halo surrounding the ‘hotspot’. In contrast, the precipitates produced in the presence of dead bacterial cells or by raising solution pH or pCO 2, i.e., hydroxylapatite, portlandite and vaterite, respectively, did not reflect the mineralogy of calcrete. Gold distribution and speciation in vaterite, formed by raising pCO 2, were homogenous and did not reproduce the variation observed in calcrete and Ca carbonates precipitated by active cells. Increasing the supersaturation with respect to Ca in solution by incremental drying of the medium produced only X-ray amorphous precipitates, or hydroxylapatite in the presence heat-killed cells. In conclusion, this study shows that active microbial processes that combine biogenic Ca carbonatogenesis with Au precipitation are likely to drive the formation of Au-anomalous calcrete.

Prolactin release and response to vasoactive intestinal peptide in an opportunistic breeder, the zebra finch ( Taeniopygia guttata)

Zebra finches in arid regions of Australia are opportunistic breeders that time their breeding cycles to coincide with nonseasonal rainfall. Hormonal profiles associated with reproductive behaviors may differ from those observed in seasonal breeders because these birds need to be reproductively competent on short notice. This study measured plasma prolactin (PRL) levels in nonbreeding and breeding zebra finches and in birds with and without prior reproductive experience. We also investigated the change in plasma PRL following injection with vasoactive intestinal peptide (VIP), the avian PRL-releasing hormone. PRL was lowest in non-paired birds, increased after pair bonds had formed, and was highest in incubating birds. No differences in PRL levels were found between males and females in these biparental care-givers. A single injection of VIP resulted in a rapid increase in plasma PRL in nonbreeding zebra finches, while PRL remained unchanged in incubating birds. When escalating doses of VIP were administered, nonbreeders responded with a maximal response in PRL release, but PRL levels in breeders remained unchanged following even the highest VIP dose. Among nonbreeders, inexperienced birds had significantly lower PRL levels than birds that had successfully reared a clutch, but both groups responded with an equally robust increase in PRL following a VIP challenge. This pattern differs from that observed in most photosensitive species in which only during a breeding cycle do birds secrete significant levels of PRL in response to exogenous VIP. Zebra finches, even when not actively breeding, must maintain competent pituitary lactotrophs that can secrete PRL at maximal rates. This is part of the suite of characters enabling these birds to respond to favorable breeding conditions at any time.

Measurement of evaporation from saline tailings storages

In the arid regions of Australia, fine-grained slurried wastes produced during gold mining are typically disposed of in large storages using subaerial deposition. Management of the storage is often aimed at maximising the evaporative drying that occurs, thereby maximising the density achieved. Ore processing is conducted using groundwater that can have salinities that approach solution saturation. Precipitation of salts on the tailings surfaces during evaporation leads to the development of thin salt crusts that can significantly reduce the rate of evaporation. Quantification of the actual rate of evaporation from the drying tailings surfaces is important for assessing disposal strategies. Different methods of estimating evaporation were employed at mine sites in Western Australia (WA) to provide more information on the drying behaviour of saline tailings. These techniques are described and typical results from a saline tailings storage are presented.

Responses of waterbirds to flooding in an arid region of Australia and implications for conservation

Floods are a frequent but irregular feature of Australia's dryland river catchments. We investigated changes in abundances of waterbirds in north western New South Wales with changes in wetland distribution at local, catchment and broad scales. The abundance of most functional groups of waterbirds changed in response to broad scale changes in wetland distribution, while local abundance remained highly variable. Patterns of abundance varied among functional groups of waterbirds, with some immediately responding to changes in wetland distribution and area flooded, and others apparently responding to sequences of wetting and drying. In Australia, the main conservation issue for waterbirds is water and its use across the landscape and not the spatial arrangement of any fixed array of reserves established to protect them.