Eyre Basin Research Articles

Return of the lignum dead: Resilience of an arid floodplain shrub to drought

In semi-arid regions, woody floodplain plants have developed methods of tolerance to both flooding and drought. Understanding the limits of tolerance to drought is critical to the efforts of restoring these communities. In Australia, Tangled Lignum (Duma florulenta (Meisn.) T. M. Schust) is an ecologically significant floodplain shrub that dominates large areas of the Murray–Darling and Lake Eyre Basins. This study investigates the resilience of lignum plants to dry periods by examining the capacity of plants to regenerate from dormancy. In particular, this study sought to test the hypothesis that lignum regeneration is influenced by increasing duration of dormancy. Variability in regeneration response across the study period was also looked at in relation to regional rainfall and flow. Lignum plants were surveyed at 12 sites on the Murray River floodplain in north-western Victoria. Sites were monitored seven times between 2006–07 and 2012–13. This study found that although lignum can regenerate from dormancy, regeneration is not guaranteed and the likelihood of successful regeneration varies among locations and diminishes with increasing length of dormancy. Lignum communities should be managed to maintain condition and resilience to drought in order to give lignum plants the greatest chance of regeneration success.

A Pliocene mekosuchine (Eusuchia: Crocodilia) from the Lake Eyre Basin of South Australia

ABSTRACTA new genus and species of crocodilian, Kalthifrons aurivellensis, is described from a channel sand deposit incised into the Oligo-Miocene Etadunna Formation on the western shore of Lake Palankarinna in the Lake Eyre Basin, South Australia. The channel sand is interpreted as an outcrop of the Mampuwordu Sand Member of the Tirari Formation, which has been assigned an early Pliocene age. The taxon can be diagnosed by the extremely elongate and narrow anterior process of the frontal pair and a distinctively beveled and laterally expanded prefrontal contribution to the orbit margin. The broadly triangular rostrum, at least partially interlocking dentition, smooth dental carinae, and weak labiolingual compression resemble unspecialized crocodilian species, and it was probably a generalist aquatic predator. It possessed character states that indicate that it was not a member of Crocodylus, and it is referred to the endemic Australasian clade Mekosuchinae. The first overlying unit in the Lake Eyre Basin sequence to produce diagnostic crocodilian remains is the mid- to late Pliocene Pompapillina Member of the Tirari Formation. It contains a true species of Crocodylus but no indication of Kalthifrons aurivellensis or indeed any other mekosuchine, indicating that the latter may have been driven to extinction via competitive replacement.http://zoobank.org/urn:lsid:zoobank.org:pub:C4E93358-D80F-4E4D-B7FF-BFFB93EDCD54SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Yates, A. M., and N. S. Pledge. 2016. A Pliocene mekosuchine (Eusuchia: Crocodilia) from the Lake Eyre Basin of South Australia. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1244540.

Holocene palaeoclimatic variations as recorded offshore south-western South Africa

In this paper we synthesise existing palaeoenvironmental data from the arid and semi-arid interior of the Australian continent for the period 40–0 ka. Moisture is the predominant variable controlling environmental change in the arid zone. Landscapes in this region respond more noticeably to changes in precipitation than to temperature. Depending on their location, arid zone records broadly respond to tropical monsoon-influenced climate regimes, the temperate latitude westerly systems, or a combination of both.The timing and extent of relatively arid and humid phases vary across the continent, in particular between the westerly wind-controlled temperate latitudes, and the interior and north which are influenced by tropically sourced precipitation. Relatively humid phases in the Murray-Darling Basin on the semi-arid margins, which were characterised by large rivers most likely fed by snow melt, prevailed from 40 ka to the Last Glacial Maximum (LGM), and from the deglacial to the mid Holocene. By contrast, the Lake Eyre basin in central Australia remained relatively dry throughout the last 40 ka, with lake high stands at Lake Frome around 35–30 ka, and parts of the deglacial period and the mid-Holocene. The LGM was characterised by widespread relative aridity and colder conditions, as evidenced by extensive desert dune activity and dust transport, lake level fall, and reduced but episodic fluvial activity. The climate of the deglacial period was spatially divergent. The southern part of the continent experienced a brief humid phase around ∼17–15 ka, followed by increased dune activity around ∼14–10 ka. This contrasts with the post-LGM persistence of arid conditions in the north, associated with a lapsed monsoon and reflected in lake level lows and reduced fluvial activity, followed by intensification of the monsoon and increasingly effective precipitation from ∼14 ka. Palaeoenvironmental change during the Holocene was also spatially variable. The early to mid-Holocene was, however, generally characterised by moderately humid conditions, demonstrated by lake level rise, source-bordering dune activity, and speleothem growth, persisting at different times across the continent. Increasingly arid conditions developed into the late Holocene, particularly in the central arid zone.

Satellite-derived mineral mapping and monitoring of weathering, deposition and erosion

The Earth’s surface comprises minerals diagnostic of weathering, deposition and erosion. The first continental-scale mineral maps generated from an imaging satellite with spectral bands designed to measure clays, quartz and other minerals were released in 2012 for Australia. Here we show how these satellite mineral maps improve our understanding of weathering, erosional and depositional processes in the context of changing weather, climate and tectonics. The clay composition map shows how kaolinite has developed over tectonically stable continental crust in response to deep weathering during northwardly migrating tropical conditions from 45 to 10 Ma. The same clay composition map, in combination with one sensitive to water content, enables the discrimination of illite from montmorillonite clays that typically develop in large depositional environments over thin (sinking) continental crust such as the Lake Eyre Basin. Cutting across these clay patterns are sandy deserts that developed <10 Ma and are well mapped using another satellite product sensitive to the particle size of silicate minerals. This product can also be used to measure temporal gains/losses of surface clay caused by periodic wind erosion (dust) and rainfall inundation (flood) events. The accuracy and information content of these satellite mineral maps are validated using published data.

Biological and physical evidence for extreme seasonality in central Permian Pangea

Climate models indicate increased desertification in the continental interior of Pangea during the Permian, which would have affected the composition of the flora and fauna. We present a multi-proxy paleoenvironmental reconstruction of a terrestrial ecosystem in central Pangea of Lopingian age. The reconstruction is based on biological and physical data from the Moradi Formation, located in the Tim Mersoi sub-Basin, northern Niger. Paleosols and sedimentological evidence indicate that the prevailing climate was semi-arid to very arid with marked intervals of high water availability. Carbon stable isotope data from organic matter and paleosols suggest that both the soil productivity and actual evapotranspiration were very low, corresponding to arid conditions. Histological analysis of pareiasaur bones shows evidence of active metabolism and reveals distinct growth marks. These interruptions of bone formation are indicative of growth rhythms, and are considered as markers for contrasting seasonality or episodic climate events. The macrofossil floras have low diversity and represent gymnosperm-dominated woodlands. Most notable are ovuliferous dwarf shoots of voltzian conifers, and a 25-m long tree trunk with irregularly positioned branch scars. The combined biological and physical evidence suggests that the Moradi Formation was deposited under a generally arid climate with recurring periods of water abundance, allowing for a well-established ground water-dependent ecosystem. With respect to its environment, this system is comparable with modern ecosystems such as the southern African Namib Desert and the Lake Eyre Basin in Australia, which are discussed as modern analogues.

Palaeoecology of Oligo-Miocene macropodoids determined from craniodental and calcaneal data

Analyses of craniodental and calcaneal material of extant macropodoids show that both dietary and locomotor types are statistically distinguishable. Application of the craniodental data to fossil macropodoids from the Oligo-Miocene of South Australia (Lake Eyre Basin) and Queensland (Riversleigh World Heritage Area) shows that these taxa were primarily omnivores or browsers. Specialized folivorous browsers were more prevalent in the Queensland deposits than in those of South Australia, suggesting more mesic conditions in the former. The calcaneal data showed that the Oligo-Miocene taxa clustered with extant generalized hoppers, in contrast to prior speculation that balbarids were quadrupedal rather than bipedal.

Dispersal in the desert: ephemeral water drives connectivity and phylogeography of an arid‐adapted fish

AbstractAimWe examine landscape processes shaping the range‐wide phylogeography of a dispersal‐limited, desert‐dwelling fish (the desert goby, Chlamydogobius eremius) in arid Australia.LocationSouth‐western Lake Eyre Basin, central Australia.MethodsWe obtained sequence data for the mitochondrial cytochrome b gene (n = 513 individuals) and nuclear genetic markers (51 allozyme loci; n ≥ 128 individuals) to investigate the phylogeographic relationships among 51 populations. Sampling spanned multiple habitat types (permanent desert springs, ephemeral rivers) and sub‐catchments, and the entire distribution of C. eremius and representatives of its sister species, Chlamydogobius japalpa. Phylogeographic analyses (genetic diversity, AMOVA, Tajima's D, WST, mismatch distribution) were used to explore the distribution and partitioning of mtDNA variation; principal coordinates analysis and neighbour‐joining tree networks were used to explore allozyme variation.ResultsThree main genetic groups exist across C. eremius/C. japalpa populations. The geographical distributions of these groups reflected the historical and current confluence point of major rivers in the region. Surprisingly, permanent desert springs did not contain higher genetic diversity than ephemeral rivers.Main conclusionsGenetic structuring of Chlamydogobius populations revealed unanticipated levels of connectivity, indicating that the ephemeral waters of Lake Eyre have allowed gene flow across drainage boundaries and large distances. Phylogeographic breaks reveal that connectivity relies on temporary surface water, while rapid temporal changes in diversity highlight flood‐driven dispersal as the main means of gene flow between localities and habitats. Dispersal pathways reveal that ecological context (life history and tolerance of extreme conditions) has played a key role in shaping observed patterns.

Correction of dust event frequency from MODIS Quick-Look imagery using in-situ aerosol measurements over the Lake Eyre Basin, Australia

Abstract Subjective visual interpretation of MODIS Quick-Look imagery has proven useful in characterising dust source geomorphology and dust event frequency over diverse areas, but is limited by the small temporal sampling window of polar orbiting platforms, and obscuration by cloud. In this paper we seek to quantify the inevitable under-reporting of dust events in Quick-Look imagery, via a three-year case study over the Lake Eyre Basin (LEB), the largest dust source in Australia and the southern hemisphere. Dust event identification from MODIS imagery is compared with the level of dust mobilization inferred from measurements of near-surface aerosol made by a continuously-operating integrating nephelometer, located at the AeroSpan/AERONET station at Tinga Tingana in the Strzelecki Desert, adjacent to major dust sources in the LEB. The analysis indicates a major upward revision in the overall dust event frequency by ~ 72%, including a doubling of the incidence of major dust outbreaks. The intensity of missed events increases toward late afternoon and evening, although without a net day-night bias. These factors suggest the potential of new geostationary sensors and the analysis of night-time polar orbiting imagery in improving the reporting of dust mobilization over active dust-source regions. For the LEB, the corrections are crucial in understanding not only the seasonal distribution of dust mobilization, but its interannual variability and climatology.

Length-length and length-weight relationships of fish species from the Lake Eyre Basin, Australia

The Lake Eyre Basin in central Australia is one of the world's last unregulated dryland river systems. To facilitate future research in this area, the relationships between total length, standard length, and wet weight for 10 widespread, large-bodied freshwater fish species are presented. All linear relationships were strong (r2 > 0.90) and values of the exponent b of the length–weight relationships ranged from 2.786 to 3.336. These results provide novel baseline data for species in this area.

Drivers of Australian dust: a case study of frontal winds and dust dynamics in the lower lake Eyre basin

AbstractThe roles of pre‐frontal, frontal and post‐frontal winds as the primary wind systems for dust entrainment and transport in Australia are well established. While the relevance of each system has been observed across different wind erosion events in central Australia, the entrainment of dust by all three winds during the passage of an individual front has not been demonstrated until now. Synoptic information, satellite aerosol and imagery, meteorological and dust concentration data are presented for a single case study erosion event in the lower Lake Eyre Basin. This event demonstrates variable dust transport in three different directions from one of the southern Hemisphere's most significant source regions, and the changing nature of the active dust pathways during the passage of a frontal system. While only a single dust event is considered, the findings show the complexity of mineral aerosol emission and transport patterns even within an individual dust outbreak. For the lower Lake Eyre Basin, this appreciation of pathway behaviour is significant for better understanding the role of aeolian inputs from the dominant Australian source to surrounding marine systems. In a wider context, the findings exhibit the detailed insights into major dust source dynamics that can be obtained from high resolution spatial and particularly temporal data, as used in combination. This work highlights the importance of adequately resolved data for the accurate determination of dust entrainment and transport patterns of major dust sources. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Where does all the water go? Partitioning water transmission losses in a data-sparse, multi-channel and low-gradient dryland river system using modelling and remote sensing

Summary Drylands cover approximately one-third of the Earth’s surface, are home to nearly 40% of the Earth’s population and are characterised by limited water resources and ephemeral river systems with an extremely variable flow regime and high transmission losses. These losses include actual evaporation, infiltration to the soil and groundwater and residual (terminal) water remaining after flood events. These critical components of the water balance of dryland river systems remain largely unknown due to the scarcity of observational data and the difficulty in accurately accounting for the flow distribution in such large multi-channel floodplain systems. While hydrodynamic models can test hypotheses concerning the water balance of infrequent flood events, the scarcity of flow measurement data inhibits model calibration, constrains model accuracy and therefore utility. This paper provides a novel approach to this problem by combining modelling, remotely-sensed data, and limited field measurements, to investigate the partitioning of flood transmissions losses based on seven flood events between February 2006 and April 2012 along a 180 km reach of the Diamantina River in the Lake Eyre Basin, Australia. Transmission losses were found to be high, on average 46% of total inflow within 180 km reach segment or 7 GL/km (range: 4–10 GL/km). However, in 180 km reach, transmission losses vary non-linearly with flood discharge, with smaller flows resulting in higher losses (up to 68%), which diminish in higher flows (down to 24%) and in general there is a minor increase in losses with distance downstream. Partitioning these total losses into the major components shows that actual evaporation was the most significant component (21.6% of total inflow), followed by infiltration (13.2%) and terminal water storage (11.2%). Lateral inflow can be up to 200% of upstream inflow (mean = 86%) and is therefore a critical parameter in the water balance and transmission loss calculations. This study shows that it is possible to constrain the water balance using hydrodynamic models in dryland river systems using remote sensing and simple field measurements to address the otherwise scarce availability of data. The results of this study also enable a better understanding of the water resources available for ecosystems in these unique multi-channel and large floodplain rivers. The combined modelling/remote sensing approach of this study can be applied elsewhere in the world to better understand the water balances and water transmission losses, important drivers of ecohydrological processes in dryland environments.

Priority threat management of non‐native plants to maintain ecosystem integrity across heterogeneous landscapes

Summary Invasive non‐native plants have negatively impacted on biodiversity and ecosystem functions world‐wide. Because of the large number of species, their wide distributions and varying degrees of impact, we need a more effective method for prioritizing control strategies for cost‐effective investment across heterogeneous landscapes. Here, we develop a prioritization framework that synthesizes scientific data, elicits knowledge from experts and stakeholders to identify control strategies, and appraises the cost‐effectiveness of strategies. Our objective was to identify the most cost‐effective strategies for reducing the total area dominated by high‐impact non‐native plants in the Lake Eyre Basin (LEB). We use a case study of the ˜120 million ha Lake Eyre Basin that comprises some of the most distinctive Australian landscapes, including Uluru‐Kata Tjuta National Park. More than 240 non‐native plant species are recorded in the Lake Eyre Basin, with many predicted to spread, but there are insufficient resources to control all species. Lake Eyre Basin experts identified 12 strategies to control, contain or eradicate non‐native species over the next 50 years. The total cost of the proposed Lake Eyre Basin strategies was estimated at AU$1·7 billion, an average of AU$34 million annually. Implementation of these strategies is estimated to reduce non‐native plant dominance by 17 million ha – there would be a 32% reduction in the likely area dominated by non‐native plants within 50 years if these strategies were implemented. The three most cost‐effective strategies were controlling Parkinsonia aculeata, Ziziphus mauritiana and Prosopis spp. These three strategies combined were estimated to cost only 0·01% of total cost of all the strategies, but would provide 20% of the total benefits. Over 50 years, cost‐effective spending of AU$2·3 million could eradicate all non‐native plant species from the only threatened ecological community within the Lake Eyre Basin, the Great Artesian Basin discharge springs. Synthesis and applications. Our framework, based on a case study of the ˜120 million ha Lake Eyre Basin in Australia, provides a rationale for financially efficient investment in non‐native plant management and reveals combinations of strategies that are optimal for different budgets. It also highlights knowledge gaps and incidental findings that could improve effective management of non‐native plants, for example addressing the reliability of species distribution data and prevalence of information sharing across states and regions.

Priority threat management of invasive animals to protect biodiversity under climate change.

Climate change is a major threat to global biodiversity, and its impacts can act synergistically to heighten the severity of other threats. Most research on projecting species range shifts under climate change has not been translated to informing priority management strategies on the ground. We develop a prioritization framework to assess strategies for managing threats to biodiversity under climate change and apply it to the management of invasive animal species across one-sixth of the Australian continent, the Lake Eyre Basin. We collected information from key stakeholders and experts on the impacts of invasive animals on 148 of the region's most threatened species and 11 potential strategies. Assisted by models of current distributions of threatened species and their projected distributions, experts estimated the cost, feasibility, and potential benefits of each strategy for improving the persistence of threatened species with and without climate change. We discover that the relative cost-effectiveness of invasive animal control strategies is robust to climate change, with the management of feral pigs being the highest priority for conserving threatened species overall. Complementary sets of strategies to protect as many threatened species as possible under limited budgets change when climate change is considered, with additional strategies required to avoid impending extinctions from the region. Overall, we find that the ranking of strategies by cost-effectiveness was relatively unaffected by including climate change into decision-making, even though the benefits of the strategies were lower. Future climate conditions and impacts on range shifts become most important to consider when designing comprehensive management plans for the control of invasive animals under limited budgets to maximize the number of threatened species that can be protected.

Australian plate motion and topography linked to fossil New Guinea slab below Lake Eyre

Unravelling causes for absolute plate velocity change and continental dynamic topography change is challenging because of the interdependence of large-scale geodynamic driving processes. Here, we unravel a clear spatio-temporal relation between latest Cretaceous–Early Cenozoic subduction at the northern edge of the Australian plate, Early Cenozoic Australian plate motion changes and Cenozoic topography evolution of the Australian continent. We present evidence for a ∼4000 km wide subduction zone, which culminated in ophiolite obduction and arc-continent collision in the New Guinea–Pocklington Trough region during subduction termination, coinciding with cessation of spreading in the Coral Sea, a ∼5 cm/yr decrease in northward Australian plate velocity, and slab detachment. Renewed northward motion caused the Australian plate to override the sinking subduction remnant, which we detect with seismic tomography at 800–1200 km depth in the mantle under central-southeast Australia at a position predicted by our absolute plate reconstructions. With a numerical model of slab sinking and mantle flow we predict a long-wavelength subsidence (negative dynamic topography) migrating southward from ∼50 Ma to present, explaining Eocene–Oligocene subsidence of the Queensland Plateau, ∼330 m of late Eocene–early Oligocene subsidence in the Gulf of Carpentaria, Oligocene–Miocene subsidence of the Marion Plateau, and providing a first-order fit to the present-day, ∼200 m deep, topographic depression of the Lake Eyre Basin and Murray–Darling Basin. We propound that dynamic topography evolution provides an independent means to couple geological processes to a mantle reference frame. This is complementary to, and can be integrated with, other approaches such as hotspot and slab reference frames.

Hydrological transformation coincided with megafaunal extinction in central Australia

Central to the debate over the extinction of many of Australia's last surviving megafauna is the question: Was climate changing significantly when humans arrived and megafauna went extinct? Here we present a new perspective on variations in climate and water resources over the last glacial cycle in arid Australia based on the study of the continent's largest lake basin and its tributaries. By dating paleoshorelines and river deposits in the Lake Eyre basin, we show that major hydrological change caused previously overflowing megalakes to enter a final and catastrophic drying phase at 48 ± 2 ka just as the giant bird, Genyornis newtoni, went extinct (50-45 ka). The disappearance of Genyornis and other megafauna has been previously attributed to "ecosystem collapse" coincident with the spread of fire-wielding humans. Our findings suggest a climate-driven hydrological transformation in the critical window of human arrival and megafaunal extinction, and the results call for a re-evaluation of a humanmediated cause for such extinctions in arid Australia.

Evolutionary history of birds across southern Australia: structure, history and taxonomic implications of mitochondrial DNA diversity in an ecologically diverse suite of species

Recent phylogeographic studies have examined the location and timing of putative Plio-Pleistocene bio-geographical barriers in moulding present-day patterns of diversity in southern Australian vertebrates. We previously investigated the divergence history of an assemblage of southern Australian birds. Here we more explicitly incorporate idiosyncratic effects of dietary ecology and habitat on the long-term demographic stability and the presence or absence of genetic structure on each of 12 species of bird. Our data suggest that the Eyrean Barrier (Flinders Ranges—Lake Eyre Basin) has been critical in shaping present-day diversity, especially that of mesic and mallee environments, and that other barriers (e.g. Murchison Barrier, Nullarbor Barrier) have played a lesser role. In contrast, nectarivory and occurrence in patchily distributed habitats are correlated with weak or no phylogeographic structure. Population expansions were most prevalent in western parts of species’ ranges. Substantial genetic divergences accompanied by moderate or no phenotypic divergence challenge traditional approaches to taxonomy in the Blue Bonnet (Northiella haematogaster), Chestnut Quail-thrush (Cinclosoma castanotum), White-eared Honeyeater (Nesoptilotis leucotis) and Scarlet Robin (Petroica boodang) and we suggest taxonomic treatments for each of these species that accommodate existing data. We elevate some taxa to species rank and note where further analyses of gene flow will be useful in clarifying remaining issues. Further phylogeographic study in the region of the Mount Lofty Ranges, Flinders Ranges, Spencer Gulf and Gulf St Vincent) of South Australia is warranted.

Is fish biomass in dryland river waterholes fuelled by benthic primary production after major overland flooding?

Dryland river foodwebs are thought to be largely driven by autochthonous production derived from littoral/benthic algae, particularly during extended periods of zero flow, with allochthonous production taking primacy after flooding as floodplain carbon is distributed into waterholes during flood recession. This study tested whether we could detect any influence of autochthonous production (littoral gross primary production) on fish biomass after flooding in Cooper Creek, a dryland river in the Lake Eyre Basin, Australia. It was found that the majority of fish biomass, mostly large carnivores, was not supported by benthic algal production. However, the biomass of juvenile bony bream Nematalosa erebi, the highly abundant benthivore of many Australian dryland rivers, was indeed driven by benthic algal productivity throughout the post-flood period, a finding also evident in post-flood waterholes in the nearby Warrego River (Murray-Darling Basin). With a consistently high abundance turnover of bony bream juveniles and their significant importance to dryland river food-webs this study demonstrates not only the need to protecting intact littoral zones for N. erebi, but by association, fish assemblages in general.

The National Heritage Potential of Landscapes Within the Australian Drylands

This paper presents a summary of an internal report on the potential National Heritage values of Australian geomorphology within a defined area. The desktop study sought information on landforms which best demonstrate the evolution of the characteristic landscapes now found in Australia's drylands. Australian dryland landscapes owe much to continental stability, which allows inheritance of landscape features and preserves the effects of previous climates. Aridity is only the latest and not always the most powerful of a long series of influences. Twenty-eight places with high potential to pass heritage criteria were identified across eight geomorphic themes (astroblemes, sand deserts, karst, arid coasts, tectonic landforms, uplands, regolith, watercourses). Some were significant within a single theme (the Acraman Impact Structure, the Nullarbor Plain); others had value across many themes/sub-themes (two Cooper Creek sites, the Neales Catchment, Rodinga Range). Many had sufficient information to identify particular locations (e.g. Gosses Bluff, the Zuytdorp Cliffs), but those without were assigned broad indicative areas, from which suitable locations can be found (e.g. the Eastern Goldfields Palaeodrainages, the Simpson Desert, the Black Soil Plains). Knowledge gaps are identified, especially the remote Great Sandy Desert and Great Victoria Desert dunefields and the Davenport–Murchison Ranges. Clusters of potential heritage occur along the Amadeus Basin ranges, and within the Lake Eyre Basin.

Challenging the concept of Aboriginal mosaic fire practices in the Lake Eyre Basin

Mosaic burning is the deliberate creation of a mosaic of patches representing different fire histories. It is often recommended for management of Australia’s natural landscapes, on the assumption that it enhances biodiversity and reduces fire hazard through increased spatial and temporal diversity of fuel loads and species composition. It is also suggested that such fire practices were used throughout Australia by traditionally living Aboriginal people. Although the creation of a patchwork of different fire histories may be an effective management tool in modern land management, the evidence for universal mosaic burning before European settlement deserves scrutiny. The records of explorers, early settlers and anthropologists relating to a large portion of the Lake Eyre Basin, particularly the Channel country and the Simpson Desert region, were examined. It is concluded that extensive gaps in the records of smokes and large fires are important and meaningful, and do not represent a failure to record fires. The case for universal mosaic burning in the region is not supported by the evidence although mosaic burning did occur in specific circumstances. Fire practices were shaped by complex and interacting factors including the vegetation and terrain type, for example the occurrence of spinifex-dominated sandhills or stony deserts; seasonal conditions and the presence or not of adequate fuel loads; how readily Aboriginal people could access country and their reasons for using or not using fire; the stocking of the pastoral country and spread of feral animals; and government policies about fire.

Lake Eyre golden perch (Macquaria sp.) spawning and recruitment is enhanced by flow events in the hydrologically variable rivers of Lake Eyre Basin, Australia

Understanding the links between fish recruitment and riverine flows is integral for setting priorities for river-management strategies, particularly in hydrologically variable and unpredictable arid and semi-arid zone rivers. In the present study, we used daily and annual otolith age estimates to identify relationships between riverine flow and spawning and recruitment of Lake Eyre golden perch (Macquaria sp.); an endemic fish of the Lake Eyre Basin, central Australia. We found a close association between Lake Eyre golden perch spawning and periods of increased river flow, with most of spawning occurring 0–35 days after the start of these flow events. Spawning occurred throughout the year but was commonly observed during the first flow events proceeding consecutive months of no-flow when water temperatures exceeded 26°C. Spawning was not dependent on floodplain inundation, with most spawning occurring during within-channel flow events. Annual average year-class strength was related to the number of flow events per year, but not total annual discharge, or the number of low-flow days per year. These results highlight the importance of natural within-channel flow patterns to Lake Eyre golden perch spawning and recruitment and demonstrate the importance of maintaining the natural flow regime of Australia’s arid- and semi-arid-zone rivers.