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Introduces a teaching strategy for Year 10 and senior biology students to demonstrate food and energy processes along a river ecosystem. In studying the River Continuum Concept, groups of students undertake a series of interrelated projects as a means of understanding the big picture of the food and energy interrelationships evident in healthy functioning ecosystems. Also includes sample hypotheses and support materials. (PVD)

Australian freshwater turtles are declining, reflecting global turtle trends. Understanding variation in turtle diets and habitat requirements can guide protection and restoration of ecosystems. Diet and niche overlap were investigated in three co‐existing species of turtle—the broad‐shelled turtle Chelodina expansa, the eastern long‐necked turtle C. longicollis and the Macquarie turtle Emydura macquarii, in three rivers in the Murray–Darling Basin, Australia, in relation to environmental variables.Dietary variation in relation to water quality (salinity) and macrophyte cover was investigated using stable isotope analyses (δ15N and δ13C) of turtle tissues (plasma, red blood cell, whole blood and nail) representing food assimilation over different antecedent periods. These stable isotope results were consistent with current dietary understanding based on stomach flushing, indicating that isotope analyses are a non‐invasive method for obtaining dietary information.There were temporal dietary differences, with strong shifts between spring and summer sampling periods, particularly in the blood plasma. Intraspecific variation in diets reflected in δ15N and δ13C related to body size. There was evidence of high dietary overlap among the three species, potentially creating competition, particularly when they co‐occur or resources might be limited.Continued degradation of turtle habitats and water quality affects turtle diet and reduces habitat availability, forcing the three species of turtle to co‐exist in diminishing refugia, increasing interspecific competition for food. Protecting and restoring freshwater ecosystems, including maintaining freshwater refugia, is essential to conserve already declining populations of the three Australian freshwater turtle species. [ABSTRACT FROM AUTHOR]

This article is underpinned by the hypothesis that if Australia is to reassess and improve its relationship to and use of rivers and river systems, then more holistic ways of understanding rivers, and strategies for representing and communicating this understanding, must be developed and brought together. Held over two days in August 2019 at the Lismore campus of Southern Cross University, 'Speaking With the River' was an interdisciplinary symposium exploring the capacities of creative research practice to develop new understandings of rivers and river systems as simultaneously environmental, cultural, historical and economic phenomena. In this article, we bring together the voices and disciplinary insights from the symposium and the rivers of Northern New South Wales, and we reflect on the way that riverine language ran throughout our discussions and ideas, providing a connective model of confluences and conjunctions for the interdisciplinary enterprise we were engaged in. This article presents perspectives on rivers and river systems from law, history, art and science, exploring common ground and common purposes. Developing a legal framework for recognising the rights and 'voices' of rivers, that is informed by Indigenous knowledges, historical contexts, and scientific understanding, and that employs artistic innovation in representation and translation, is to us the ultimate goal of such an enquiry. While this paper does not undertake the formal steps of developing this framework, it provides the necessary background and instantiates its elements and working methods within the context of the Richmond River in Northern New South Wales. [ABSTRACT FROM AUTHOR]

In Australia the impacts of climate change are resulting in considerable water scarcity, a scenario affecting the green and blue spaces that provide well-recognized individual health benefits. However, far less is known about the social health benefits of these spaces, particularly for those residing in rural Australian river communities. In this geographic context, water issues are compounded by a dominant culture that privileges the commodification of water for agricultural purposes over other interests. Using an environmental justice perspective consistent with a green social work approach, this proof-of-concept study contributes a critical element to water debates by examining the cultural, recreational, and environmental meanings of water for the rural river community of Mildura. Results from an online mixed-methods questionnaire (N = 33) show that people privileged cultural meanings of water as fundamental to life, were concerned for river health, and felt marginalized in water debates. Findings suggest that understanding communities' hydrosocial relationships is key to environmentally and socially just water management and to individual, community, and environmental health. Social work can contribute to such environmental issues by working collaboratively to enable communities to exercise their voices and to advocate to decision makers to include consideration of environmental, social, and cultural impact. [ABSTRACT FROM AUTHOR]

Vegetation condition has declined along many regulated river systems globally due to alteration of flow regimes via flow regulation. Understanding how plants respond to inundation is critical for managing regulated river flows to improve riparian vegetation condition. We experimentally tested the effects of inundation duration on the survival and growth of six tufted grass species commonly found in riparian zones in south-eastern Australia. We conducted three nursery-based experiments in late winter/early spring, corresponding with natural temperate flow peaks and managed flows, with inundation treatments on: (1) established plants, up to 35 days inundation; (2) seedlings, up to 25 days inundation; and (3) established plants, up to 53 days inundation including additional shaded treatments. Plant survival, height and biomass growth, and onset of flowering were recorded for established plants, and, for seedlings, survival only. Plant height and biomass growth declined with longer inundation duration across all species, although surprisingly few established plants died. Unexpectedly, grass seedlings were generally tolerant of inundation also, although there was some evidence of increased mortality for the longest treatment (25 days inundation). Shading did not result in increased mortality or reduced height growth of inundated plants. Inundation effects on the onset of flowering were modest and varied between species ranging from earlier to delayed onset. Our results suggest that tufted grasses are tolerant of cool-season inundation. Given that mortality of these species has been observed in the field and experimentally under shorter inundation periods in warmer conditions (late spring and summer), we suggest that seasonal timing of inundation is critical in determining plant responses to inundation. [ABSTRACT FROM AUTHOR]

Climate change is altering hydrological cycles globally, and in Mediterranean (med‐) climate regions it is causing the drying of river flow regimes, including the loss of perennial flows. Water regime exerts a strong influence over stream assemblages, which have developed over geological timeframes with the extant flow regime. Consequently, sudden drying in formerly perennial streams is expected to have large, negative impacts on stream fauna. We compared contemporary (2016/17) macroinvertebrate assemblages of formerly perennial streams that became intermittently flowing (since the early 2000s) to assemblages recorded in the same streams by a study conducted pre‐drying (1981/82) in the med‐climate region of southwestern Australia (the Wungong Brook catchment, SWA), using a multiple before‐after, control‐impact design. Assemblage composition in the stream reaches that remained perennial changed very little between the studies. In contrast, recent intermittency had a profound effect on species composition in streams impacted by drying, including the extirpation of nearly all Gondwanan relictual insect species. New species arriving at intermittent streams tended to be widespread, resilient species including desert‐adapted taxa. Intermittent streams also had distinct species assemblages, due in part to differences in their hydroperiods, allowing the establishment of distinct winter and summer assemblages in streams with longer‐lived pools. The remaining perennial stream is the only refuge for ancient Gondwanan relict species and the only place in the Wungong Brook catchment where many of these species still persist. The fauna of SWA upland streams is becoming homogenised with that of the wider Western Australian landscape, as drought‐tolerant, widespread species replace local endemics. Flow regime drying caused large, in situ alterations to stream assemblage composition and demonstrates the threat posed to relictual stream faunas in regions where climates are drying. [ABSTRACT FROM AUTHOR]

The gold rush at the end of the nineteenth century in south-eastern Australia resulted in the mobilization and re-deposition of vast quantities of tailings that modified the geomorphology of the associated river valleys. Previous studies of contamination risk in these systems have either been performed directly on mine wastes (e.g., battery sand) or at locations close to historical mine sites but have largely ignored the extensive area of riverine alluvial deposits extending downstream from gold mining locations. Here we studied the distribution of contaminant metal(loids) in the Loddon River catchment, one of the most intensively mined areas of the historical gold-rush period in Australia (1851-1914). Floodplain alluvium along the Loddon River was sampled to capture differences in metal and metalloid concentrations between the anthropogenic floodplain deposits and the underlying original floodplain. Elevated levels of arsenic up to 300 mg-As/kg were identified within the anthropogenic alluvial sediment, well above sediment guidelines (ISQG-high trigger value of 70 ppm) and substantially higher than in the pre-mining alluvium. Maximum arsenic concentrations were found at depth within the anthropogenic alluvium (plume-like), close to the contact with the original floodplain. The results obtained here indicate that arsenic may pose a significantly higher risk within this river catchment than previously assessed through analysis of surface floodplain soils. The risks of this submerged arsenic plume will require further investigation of its chemical form (speciation) to determine its mobility and potential bioavailability. Our work shows the long-lasting impact of historical gold mining on riverine landscapes., (© 2024. The Author(s).)

Conservation management of freshwater ecosystems often focuses on mitigating or reversing the negative effects of altered patterns of river discharge. Assessments of management interventions frequently focus on direct, short‐term responses to discharge without consideration of underlying population trends that span multiple years.We sought to determine the effects on fish populations of annual variation in river discharge and water temperature after accounting for underlying population trends. We used data on five native and one non‐native fish species, collected over 7–20 years in seven rivers in the Murray‐Darling Basin, south‐eastern Australia.Population trends explained 3.4%–24.6% of the total variation in abundance and biomass of our six study species, while discharge and water temperature explained a further 1.2%–11.4% of this variation. However, population trends confounded the effects of discharge and water temperature, which suggests that the effects of annual discharge conditions may be contingent on past conditions and factors intrinsic to populations (e.g. age structure).Failing to account for population trends led to a combination of plausible and implausible associations with discharge and water temperature. Plausible associations included positive associations with the magnitude of spring discharge and negative associations with the number of days where discharge was below the long‐term 10th percentile. Determining whether estimated associations are real or artefactual requires a greater focus on the processes that underpin multiyear population trends.Our results highlight the potential for underlying trends in populations to confound the short‐term effects of discharge. Potential confounding of short‐ and long‐term changes in populations underscores the need to assess responses to river discharge in the context of overarching environmental conditions, including factors other than discharge. [ABSTRACT FROM AUTHOR]

Bucket dredging to mine and extract gold and tin from rivers is a global industry that has had a range of negative effects on physical environments. These include the destruction of riparian soil profiles and structures, artificial channel straightening and loss of in-stream biodiversity. In this paper we evaluate the immediate effects and long-term consequences of bucket dredging on rivers in Victoria and New South Wales during the period 1900–1950. High quality historical sources on dredge mining are integrated with geospatial datasets, aerial imagery and geomorphological data to analyse the scale of the dredging industry, evidence for disturbance to river channels and floodplains and current land use in dredged areas. The study demonstrates that the environmental impact of dredging was altered but not reduced by anti-pollution regulations intended to control dredging. An assessment of river condition 70–100 years after dredge mining ceased indicates that floodplains and river channels continue to show the effects of dredging, including bank erosion, sediment slugs, compromised habitat and reduced agricultural productivity. These findings have significant implications for river and floodplain management. [ABSTRACT FROM AUTHOR]

The presence of threatened or endangered species often strongly influences management and conservation decisions. Within the Murray–Darling Basin (MDB), Australia, the presence of threatened native fish affects the management and allocation of water resources. In New South Wales, these decisions are currently based on traditional fisheries data and a predictive MaxEnt model. However, it is important to verify the model's predictive power given the implication it may have, but this requires methods with a high detection sensitivity for rare species.Although the use of environmental DNA (eDNA) monitoring, in particular eDNA metabarcoding, achieves a higher detection sensitivity compared with traditional methods, earlier surveys in the MDB have shown that the highly abundant and invasive common carp (Cyprinus carpio) can reduce detection probabilities for rare species. Consequently, a polymerase chain reaction (PCR) blocking primer designed to block the amplification of carp eDNA could increase the detection probabilities for rare native species while simultaneously reducing the required sampling effort and survey costs. Although PCR blocking primers are often used in ancient DNA and dietary studies, no aquatic eDNA metabarcoding study to date has evaluated the potential benefits of using PCR blocking primers.A laboratory and field‐based pilot study was used to address this knowledge gap and assess the impact of a blocking primer, targeting cyprinid fishes (including carp), on the detection probabilities of native species and the minimum sampling effort required.Results showed that the inclusion of the blocking primer increased the detection probabilities for native species by 10–20% and reduced the minimum required sampling effort by 25–50%. These findings provide important insights into possible methods for optimizing eDNA metabarcoding surveys for the detection of rare aquatic species. [ABSTRACT FROM AUTHOR]

Acts of remembering a river may have a performative function in environmental history and debates around human impact and waterways. The process of remembering and search for meaning are shaped in the present moment when the Richmond is one of the most degraded river systems on the east coast of Australia. Imbued with sentimentality, however, residents speak to the fundamental importance of the river to their lives as they were growing up in and around Lismore. Such histories may provide context for understanding contemporary affective responses to rivers and how emotion shapes our relationships with nature more broadly. [ABSTRACT FROM AUTHOR]

Protecting headwater streams is essential to minimise downstream sediment loads to rivers, estuaries, and oceans. This study analyses the gully and sheet erosion risk from a 33,000 ha agricultural development proposal in the Normanby catchment draining to the Great Barrier Reef (GBR) Lagoon, Australia. The slope‐area threshold for channel initiation was assessed for existing gully channel head locations using satellite images and a hydrologically enforced digital elevation model (SRTM). Thresholds were used to predict whether other stream lines (1:25k scale) were prone to gully incision under development. Results indicated that 430 km out of 1,200 km of streams were at risk of gullying, which could increase erosion by 2‐times, delivering 7,500 t yr−1 locally and 1,700 t yr−1 (worth A$1.8 million) to the GBR. Sheet erosion under agriculture is estimated (RUSLE) to increase by 13‐times from 0.12 to 1.5 t ha−1 yr−1, with 2,200 t yr−1 to streams and 900 t yr−1 (worth A$1 million) to the GBR. Buffering (±50 m) 560 km of headwater streams would cover 5,600 ha or 17% of the area. Precision agriculture using higher resolution topographic data (LiDAR) and improved slope‐area thresholds for gully erosion should be a minimum prerequisite for development, which would reduce but not eliminate increased sediment loads to the GBR. Forest clearance for agriculture is ongoing in Australia, but this first‐world country does not have effective policies or regulations to protect headwater streams or cumulative impacts to the World Heritage Great Barrier Reef, despite millions of dollars spent annually to reduce past land degradation. [ABSTRACT FROM AUTHOR]

A fundamental premise of river management is that practitioners understand the resource they are working with. In river management this requires that baseline information is available on the structure, function, health and trajectory of rivers. Such information provides the basis to contextualise, to plan, to be proactive, to prioritise, to set visions, to set goals and to undertake objective, pragmatic, transparent and evidence-based decision making. In this paper we present the State-wide NSW River Styles database, the largest and most comprehensive dataset of geomorphic river type, condition and recovery potential available in Australia. The database is an Open Access product covering over 216,600 km of stream length in an area of 802,000 km2. The availability of the database presents unprecedented opportunities to systematically consider river management issues at local, catchment, regional and state-wide scales, and appropriately contextualise applications in relation to programs at other scales (e.g. internationally)–something that cannot be achieved independent from, or without, such a database. We present summary findings from the database and demonstrate through use of examples how the database has been used in geomorphologically-informed river management. We also provide a cautionary note on the limitations of the database and expert advice on lessons learnt during its development to aid others who are undertaking similar analyses. [ABSTRACT FROM AUTHOR]

Monitoring pesticide run-off in the aquatic environment is ecologically important. Effective methods are required to detect the wide range of possible pesticides that enter estuaries from the surrounding catchment. Here, we investigate the occurrence of pesticides in the Richmond River estuary, Australia, and compare the effectiveness of using oysters and Chemcatcher® passive sampling devices against composite water samples. Samples were collected from six sites during two sampling periods: from January to March 2020 (4 weekly composite water samples and oyster collections) and from February to March 2021 (8 twice weekly composite water samples and Chemcatcher® deployment). Samples were analysed for up to 174 pesticides. A total of 21 pesticides were detected across all sites using all methods. The number of pesticides and mixture of pesticides detected in the 2020 sampling was higher in oyster samples than in water samples. In 2021, Chemcatcher® samplers detected more pesticides than in water samples. Herbicides were the most common in all samples. Insecticides and most fungicides were detected only in oysters and Chemcatcher®. Overall, the use of three complementary sampling approaches demonstrated a high level of pesticide input into the Richmond River estuary, highlighting the usefulness of oysters as biomonitors for some pesticides., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Heavy metals (Ni, Cr, W, Cd, and Pb) and rare earth elements (REE) were investigated in the flood plain sediments of an island of the lower Yangtze River near Nanjing to determine how the vertical distribution of heavy metals could be affected by natural sedimentation processes and anthropogenic contamination. Stratigraphic analyses of magnetic susceptibility and the mean grain size distribution of the deposits enabled us to identify layers associated with a relatively high influx of suspended sediments that resulted in sudden changes in the concentrations of heavy metals. The results show that layers associated with high sediment influx (0.8 m depth) displayed low concentrations of Cr, Ni, W, and Cd that were mainly lithogenic in origin. The Post Archean Australian Shale (PAAS) normalized REE patterns in the flood plain cores were enrichment in Ce and Eu relative to PAAS, indicating that the sediments were most likely derived from a mixture of sediments and not from an anthropogenic source. Sharp increases in Y/Ho ratios, as well as heavy metal (Cd, Cr, Ni, and W) and Y concentrations were observed in the uppermost layer that could have been deposited from the rapid transport of sediment-laden, contaminated waters. The temporal (vertical) trends in Pb concentrations may be strongly influenced by coal burning. Elevated Pb concentrations (350 ppm and 1000 ppm) correlate with high magnetic susceptibility (> 200 m 3  × kg -1 ) and the history of thermal power plant (1910-2002) activity. The anthropogenic inputs of Pb were, however, not diluted by high suspended sediment loads, which supports the argument that Pb was derived from fly ash., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

There is a growing interest globally in the spatial distribution and temporal dynamics of intermittently flowing streams and rivers, and how this varies in relation to climatic and other environmental factors. However, biases in the distribution of stream gauges may give a misleading impression of spatial-temporal variations in streamflow intermittency within river networks. Here, we developed an approach to quantify catchment-wide streamflow intermittency over long time frames and in a spatially explicit manner, using readily accessible and spatially contiguous daily runoff data from a national-scale water balance model. We examined the ability of the water balance model to simulate streamflow in two hydro-climatically distinctive (subtropical and temperate) regions in Australia, with a particular focus on low-flow simulations. We also evaluated the effect of model time step (daily vs. monthly) on flow intermittency estimation to inform future model selection. The water balance model showed better performance in the temperate region characterised by steady baseflow than in the subtropical region with flashy hydrographs and frequent cease-to-flow periods. The model tended to overestimate low-flow magnitude mainly due to overestimation of gains (e.g. groundwater release to baseflow) during low-flow periods. Modelled patterns of flow intermittency revealed highly dynamic behaviour in space and time, with cease-to-flow events affecting between 29 and 80 % of the river network over the period of 1911–2016, using a daily streamflow model. The daily flow model did not perform better than the monthly flow model in quantifying flow intermittency at a monthly time step, and model selection should depend on the intended application of the model outputs. Our general approach to quantifying spatio-temporal patterns of flow intermittency is transferable to other parts of the world, and it can inform hydro-ecological understanding and management of intermittent streams where limited gauging data are available. [ABSTRACT FROM AUTHOR]

Tropical rivers and estuaries are highly dynamic environments, where environmental conditions change dramatically over spatial and temporal scales. This creates both physiological and ecological challenges for euryhaline elasmobranchs, where fluctuations in salinity can impact not only osmoregulatory function but also the ability to find and acquire prey.We investigated how spatial and temporal variation in environmental salinity influences physiological homoeostasis, habitat utilization and migration timing in two euryhaline carcharhinid sharks within a tropical river in northern Australia. Neonate and juvenile bull sharks Carcharhinus leucas and speartooth sharks Glyphis glyphis were tracked over a 4‐year period using implanted acoustic tags and an array of hydrophone receivers. Tissue samples were also collected from captured sharks and analysed for interspecific differences in plasma osmolarity, urea and electrolyte (Na+ and K+) concentrations and the stable isotopes δ13C and δ15N.We discovered that immature C. leucas and G. glyphis segregate spatially along a salinity gradient between September and December, where the mean volume of intersection between species dropped as low as 0.01. While G. glyphis used higher salinity environments (mean salinity = 19.22) located between 30 and 70 km from the mouth of the estuary, C. leucas occupied freshwater reaches (mean salinity = 1.98) between 60 and 110 km upstream. Plasma osmolarities of both species were always hyperosmotic to the environment, with electrolyte concentrations maintained within a narrow range independent of environmental osmolarities. At the onset of the wet season, both C. leucas and G. glyphis undertook a coordinated downstream migration towards the lower estuary before returning upstream.Carcharhinus leucas blood tissues were more enriched in δ15N and δ13C than samples collected from similar size G. glyphis, suggesting that these species not only spatially segregate within low salinity habitats but also prey on different dietary resources. Furthermore, a loss of enriched isotopic values in fin tissue with increasing body length provides further support for marine use by adult sharks in conjunction with dependence on rivers as important nursery habitat. Our results illustrate the importance of long‐term integrative studies into resource competition and the significance of discrete brackish habitats for threatened euryhaline elasmobranchs. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Background: Ross River virus (RRV) is responsible for the most common vector-borne disease of humans reported in Australia. The virus circulates in enzootic cycles between multiple species of mosquitoes, wildlife reservoir hosts and humans. Public health concern about RRV is increasing due to rising incidence rates in Australian urban centres, along with increased circulation in Pacific Island countries. Australia experienced its largest recorded outbreak of 9544 cases in 2015, with the majority reported from south east Queensland (SEQ). This study examined potential links between disease patterns and transmission pathways of RRV.Methods: The spatial and temporal distribution of notified RRV cases, and associated epidemiological features in SEQ, were analysed for the period 2001-2016. This included fine-scale analysis of disease patterns across the suburbs of the capital city of Brisbane, and those of 8 adjacent Local Government Areas, and host spot analyses to identify locations with significantly high incidence.Results: The mean annual incidence rate for the region was 41/100,000 with a consistent seasonal peak in cases between February and May. The highest RRV incidence was in adults aged from 30 to 64 years (mean incidence rate: 59/100,000), and females had higher incidence rates than males (mean incidence rates: 44/100,000 and 34/100,000, respectively). Spatial patterns of disease were heterogeneous between years, and there was a wide distribution of disease across both urban and rural areas of SEQ. Overall, the highest incidence rates were reported from predominantly rural suburbs to the north of Brisbane City, with significant hot spots located in peri-urban suburbs where residential, agricultural and conserved natural land use types intersect.Conclusions: Although RRV is endemic across all of SEQ, transmission is most concentrated in areas where urban and peri-urban environments intersect. The drivers of RRV transmission across rural-urban landscapes should be prioritised for further investigation, including identification of specific vectors and hosts that mediate human spillover. [ABSTRACT FROM AUTHOR]

Ross River virus (RRV) is the most common and widespread arbovirus in Australia. Epidemiological models of RRV increase understanding of RRV transmission and help provide early warning of outbreaks to reduce incidence. However, RRV predictive models have not been systematically reviewed, analysed, and compared. The hypothesis of this systematic review was that summarising the epidemiological models applied to predict RRV disease and analysing model performance could elucidate drivers of RRV incidence and transmission patterns. We performed a systematic literature search in PubMed, EMBASE, Web of Science, Cochrane Library, and Scopus for studies of RRV using population-based data, incorporating at least one epidemiological model and analysing the association between exposures and RRV disease. Forty-three articles, all of high or medium quality, were included. Twenty-two (51.2%) used generalised linear models and 11 (25.6%) used time-series models. Climate and weather data were used in 27 (62.8%) and mosquito abundance or related data were used in 14 (32.6%) articles as model covariates. A total of 140 models were included across the articles. Rainfall (69 models, 49.3%), temperature (66, 47.1%) and tide height (45, 32.1%) were the three most commonly used exposures. Ten (23.3%) studies published data related to model performance. This review summarises current knowledge of RRV modelling and reveals a research gap in comparing predictive methods. To improve predictive accuracy, new methods for forecasting, such as non-linear mixed models and machine learning approaches, warrant investigation. Author summary: As the most common human arbovirus infection in Australia, Ross River virus exerts a significant public health and economic burden on the population. Because the virus is transmitted by mosquitoes, incidence is influenced by climate, environment, and socio-economic factors. Using epidemiological models to predict incidence or outbreaks of RRV fully utilises these data to inform decision-making. In this systematic review, we summarised models and their predictive performance, and highlighted significant exposures in order to increase understanding of transmission. [ABSTRACT FROM AUTHOR]

Streams and rivers are biodiverse and provide valuable ecosystem services. Maintaining these ecosystems is an important task, so organisations often monitor the status and trends in stream condition and biodiversity using field sampling and, more recently, autonomous in-situ sensors. However, data collection is often costly, so effective and efficient survey designs are crucial to maximise information while minimising costs. Geostatistics and optimal and adaptive design theory can be used to optimise the placement of sampling sites in freshwater studies and aquatic monitoring programs. Geostatistical modelling and experimental design on stream networks pose statistical challenges due to the branching structure of the network, flow connectivity and directionality, and differences in flow volume. Geostatistical models for stream network data and their unique features already exist. Some basic theory for experimental design in stream environments has also previously been described. However, open source software that makes these design methods available for aquatic scientists does not yet exist. To address this need, we present SSNdesign, an R package for solving optimal and adaptive design problems on stream networks that integrates with existing open-source software. We demonstrate the mathematical foundations of our approach, and illustrate the functionality of SSNdesign using two case studies involving real data from Queensland, Australia. In both case studies we demonstrate that the optimal or adaptive designs outperform random and spatially balanced survey designs implemented in existing open-source software packages. The SSNdesign package has the potential to boost the efficiency of freshwater monitoring efforts and provide much-needed information for freshwater conservation and management. [ABSTRACT FROM AUTHOR]

Transmission of vector-borne pathogens can vary in complexity from single-vector, single-host systems through to multivector, multihost vertebrate systems. Understanding the dynamics of transmission is important for disease prevention efforts, but is dependent on disentangling complex interactions within coupled natural systems. Ross River virus (RRV) is a multivector multihost pathogen responsible for the greatest number of notified vector-borne pathogen infections in humans in Australia. Current evidence suggests that nonhuman vertebrates are critical for the maintenance and spillover of RRV into mosquito populations. Yet, there is a limited knowledge of which mosquito vector species and amplifying vertebrate host species are most important for transmission of RRV to humans. We conducted field surveys of nonhuman vertebrates and mosquitoes in the RRV endemic city of Brisbane, Australia, to assess the effect of vector and host community structure on human RRV notifications. Six suburbs were selected across a gradient of human disease notification rates. Differences in vertebrate and mosquito compositions were observed across all suburbs. Suburbs with higher RRV notification rates contained greater vertebrate biomass (dominated by the presence of horses) and higher mosquito abundances. This study suggests that horse–mosquito interactions should be considered in more detail and that vertebrate biomass and mosquito abundance be incorporated into future RRV modeling studies and considered in public health strategies for RRV management. [ABSTRACT FROM AUTHOR]

Discharge event frequency, magnitude and duration all control river channel morphology and sedimentary architecture. Uncertainty persists as to whether alluvial deposits in the rock record are a time‐averaged amalgam from all discharge events, or a biased record of larger events. This paper investigates the controls on channel deposit character and subsurface stratigraphic architecture in a river with seasonal discharge and very high inter‐annual variability, the Burdekin River of north‐east Australia. In such rivers, most sediment movement is restricted to a few days each year and at other times little sediment moves. However, the maximum discharge magnitude does not directly correlate with the amount of morphological change and some big events do not produce large deposits. The Burdekin channel deposits consist of five main depositional elements: (i) unit bars; (ii) vegetation‐generated bars; (iii) gravel sheets and lags; (iv) antidune trains; and (v) sand sheets. The proportions of each depositional element preserved in the deposits depend on the history of successive large discharge events, their duration and the rate at which they wane. Events with similar peak magnitude but different rate of decline preserve different event deposits. The high intra‐annual and inter‐annual discharge variability and rapid rate of stage change make it likely that small to moderate‐scale bed morphology will be in disequilibrium with flow conditions most of the time. Consequently, dune and unit bar size and cross‐bed set thickness are not good indicators of event or channel size. Antidunes may be more useful as indicators of flow conditions at the time they formed. Rivers with very high coefficient of variance of maximum discharge, such as the Burdekin, form distinctive channel sediment bodies. However, the component parts are such that, if they are examined in isolation, they could lead to misleading interpretation of the nature of the depositional environment if conventional interpretations are used. [ABSTRACT FROM AUTHOR]

Quaternary alluvial and colluvial sediments infill major river valleys and form alluvial fans and colluvium-filled bedrock depressions on the range fronts and within the Mount Lofty Ranges of southern Australia. A complex association of alluvial successions occurs in the Sellicks Creek drainage basin, as revealed from lithostratigraphy, physical landscape setting and optically stimulated luminescence (OSL) ages. Correlation of OSL ages with the Marine Oxygen Isotope record reveals that the alluvial successions represent multiple episodes of alluvial sedimentation since the penultimate glaciation (Marine Isotope Stage 6; MIS 6). The successions include a penultimate glacial maximum alluvium (Taringa Formation; 160 ± 15 ka; MIS 6), an unnamed alluvial succession (42 ± 3.2 ka; MIS 3), a late last glacial colluvial succession within bedrock depressions (ca 15 ka; MIS 2) and a late last glacial alluvium (ca 15 ka; MIS 2) in the lowest, distal portion of Sellicks Creek. In addition, the Waldeila Formation, a Holocene alluvium (3.5 ± 0.3 ka; MIS 1), and sediments deposited during a phase of Post-European Settlement Aggradation (PESA) are also identified. The age and spatial distribution of the red/brown successions, mapped as the Upper Pleistocene Pooraka Formation, directly relate to different topographic and tectonic settings. Neotectonic uplift locally enhanced erosion and sedimentation, while differences in drainage basin sizes along the margin of the ranges have influenced the timing and delivery of sediment in downstream locations. Close to the Willunga Fault Scarp at Sellicks Creek, sediments resembling the Pooraka Formation have yielded a pooled mean OSL age of 83.9 ± 7 ka (MIS 5a) corroborating the previously identified extended time range for deposition of the formation. Elsewhere, within major river valleys, the Pooraka Formation was deposited during the last interglacial maximum (128–118 ka; MIS 5e). In general, alluviation occurred during interglacial and interstadial pluvial events, while erosion predominated during drier glacial episodes. In both cases, contemporaneous erosion and sedimentation continued to affect the landscape. For example, in the Sellicks Creek drainage basin, which lies across an actively uplifting fault zone, late glacial age sediments (MIS 2) occur within the ranges and near the distal margin of the alluvial fan complex. OSL dating of the alluvial successions reported in this paper highlights linkages between the terrestrial and marine environments in association with sea-level (base-level) and climatic perturbations. While the alluvial successions relate largely to climatically driven changes, especially in major river valleys, tectonics, eustasy, geomorphic setting and topography have influenced erosion and sedimentation, especially on steep-sloped alluvial fan environments. Luminescence dating of the Sellicks Creek alluvial fan complex reveals that sedimentation occurred predominantly during the later stages of glacial cycles accompanying lower sea-levels than present. Luminescence dating confirms that the stratigraphically lower portions of the Pooraka Formation are beyond the range of radiocarbon dating. Upper Pleistocene alluvial fan sedimentation at Sellicks Creek correlates with pluvial events in southeastern Australia. [ABSTRACT FROM AUTHOR]

Mobilisation of large volumes of bedrock, regolith and soil has long been a characteristic feature of metal mining. Before the 20th century this was most efficiently achieved through harnessing the motive power of water. Large‐scale water use in mining produced waste sands, gravels and silts that were flushed downstream, triggering changes in stream and floodplain morphology and function. During the 19th century the shift from artisanal to industrialised mining resulted in a rapid increase in the scale and extent of environmental change. This paper presents results from a multidisciplinary research programme investigating the environmental effects of 19th‐century gold mining on waterways in south‐eastern Australia. Archaeological and geospatial landscape survey are combined with historical data modelling and geomorphological analysis to examine the extractive processes that produced sediment in headwater regions and how this influenced fluvial processes operating on downstream waterways and floodplains. Our case study of the Three Mile‐Hodgson Creek system on the Ovens (Beechworth) goldfield in north‐east Victoria indicates that miners mobilised up to 7.3 million m3 of sediment in this small catchment alone. Results of the research suggest that tailings dams and sludge channels in this catchment are important archaeological evidence for early attempts to manage industrial waste. [ABSTRACT FROM AUTHOR]

Experimental floods, generated downstream of dams, are used to recover specific bio‐geomorphic functions in regulated rivers. Studies of the effects of experimental floods vary in their objective, location, and the hydrological and bio‐geomorphic variables used to quantify recovery. Measurements of geomorphic change are required to guide future release strategies. The focus of this study was to determine if a large experimental flood in the Snowy River Australia, could promote geomorphic recovery of the river channel downstream of Jindabyne Dam following 35 years of flow regulation. The objectives of the release were to deepen, widen, and increase channel capacity and coarsen the riverbed substratum in the Jindabyne Gorge and Dalgety Uplands sections of the Snowy River. Data from the release were compared with that of a natural flood event that occurred after the experimental flow event. Both events showed channel adjustments and a degree of geomorphic recovery, but this varied between the two river sections. Marked channel adjustments occurred in the Dalgety Uplands reach following both the experimental and natural flood event and in the Jindabyne Gorge section following the natural flood event. Geomorphic changes were related to the hydrological character of each flood event. The number of flood peaks, the sequence of peaks, the flood duration, and the total energy expenditure differed markedly between the two events, and these four flood hydrological characteristics explained the greater geomorphic recovery associated with the natural flood event in the Jindabyne Gorge. No clear hydro‐geomorphic relationship was derived for channel change in the Dalgety Uplands where existing morphological constraints limit flood effectiveness. [ABSTRACT FROM AUTHOR]

Soil erosion poses a significant threat to river health as well as the sustainability of soil resources. Management of this issue requires catchment‐specific data to be developed; however, many large catchments are poor in terms of hydrological and sediment transport data. Regional scale (thousands of square kilometres), computer‐based modelling methods are a way to generate such data. This study aims to apply the SedNet model to estimate a sediment budget for a 575 km2, ungauged, agricultural catchment of south‐eastern Australia. The model results are then compared with field measured erosion rates for the catchment, in order to assess the sustainability of soil loss and redistribution across the catchment. SedNet estimated average suspended sediment concentrations between 70 and 120 mg/L, under conditions deemed most representative of the river. These model estimates were comparable with monitoring data, showing suspended sediment concentrations between 30 and 350 mg/L. It was found that soil loss and redistribution across the catchment is low; however, the estimated base sediment loads indicate that river health may be negatively impacted by this. SedNet accurately represented current catchment and river conditions and provided a reliable estimation of sediment yield, demonstrating the ability to estimate sediment loss and redistribution across data‐poor catchments using a multifaceted modelling approach. Methodologies, such as the one presented here, offer the ability to better assess the impacts of erosion on sediment loads to develop strategies to effectively manage excess suspended sediment. [ABSTRACT FROM AUTHOR]

The construction of dams significantly alters flow and sediment regimes with subsequent deleterious effects on the morphological and ecological character of rivers. Effective experimental floods can ameliorate the downstream geomorphic impacts of dams. The traditional view is that large floods are required to perform effective geomorphic work, and the geomorphic outcomes of small floods are often overlooked. Many river restoration frameworks do not consider small floods. Yet, there is evidence that the hydrological characteristics that ameliorate specific geomorphic impacts in a river are unique to each river, and a customised approach to setting the right mix of floods (including small experimental floods) is needed. In this study, we modify an existing flood effectiveness model developed for large floods, for determining the geomorphic effectiveness of small floods in a highly regulated Australian river. Two flood classes were added to the model (medium peak stream power and moderate total energy expenditure), and the flood power characteristics were rescaled to reflect the relative difference in the magnitude of the small floods and the magnitude of the geomorphic work performed. Using a step‐wise approach, this customised model determined the geomorphic effectiveness of small floods. The best flood for ameliorating the geomorphic impacts of flow regulation had medium to long duration (10 to 51 days), high peak unit stream power (77 to 123 Wm−2) and moderate to large total energy expenditure (78,600 to 342,320 × 103 J). This approach to determining flood effectiveness for small floods is applicable to other geomorphically impacted river channels downstream of dams and can be used to inform experimental flood releases for geomorphic outcomes. [ABSTRACT FROM AUTHOR]

Rivers provide crucial ecosystem services in water-stressed drylands. Australian dryland rivers are geomorphologically diverse, ranging from through-going, single channels to discontinuous, multi-channelled systems, yet we have limited understanding of their sensitivity to future hydroclimatic changes. Here, we characterise for the first time the geomorphology of 29 dryland rivers with catchments across a humid to arid gradient covering >1,800,000 km2 of continental eastern and central Australia. Statistical separation of five specific dominantly alluvial river types and quantification of their present-day catchment hydroclimates enables identification of potential thresholds of change. Projected aridity increases across eastern Australia by 2070 (RCP4.5) will result in ~80% of the dryland rivers crossing a threshold from one type to another, manifesting in major geomorphological changes. Dramatic cases will see currently through-going rivers (e.g. Murrumbidgee, Macintyre) experience step changes towards greater discontinuity, characterised by pronounced downstream declines in channel size and local termination. Expanding our approach to include other river styles (e.g. mixed bedrock-alluvial) would allow similar analyses of dryland rivers globally where hydroclimate is an important driver of change. Early identification of dryland river responses to future hydroclimatic change has far-reaching implications for the ~2 billion people that live in drylands and rely on riverine ecosystem services. [ABSTRACT FROM AUTHOR]

Ross River virus (RRV) belongs to the genus Alphavirus and is prevalent in Australia. RRV infection can cause arthritic symptoms in patients and may include rash, fever, arthralgia, and myalgia. Type I interferons (IFN) are the primary antiviral cytokines and trigger activation of the host innate immune system to suppress the replication of invading viruses. Alphaviruses are able to subvert the type I IFN system, but the mechanisms used are ill defined. In this study, seven RRV field strains were analyzed for induction of and sensitivity to type I IFN. The sensitivities of these strains to human IFN-γ varied significantly and were highest for the RRV 2548 strain. Compared to prototype laboratory strain RRV-T48, RRV 2548 also induced higher type I IFN levels both in vitro and in vivo and caused milder disease. To identify the determinants involved in type I IFN modulation, the region encoding the nonstructural proteins (nsPs) of RRV 2548 was sequenced, and 42 amino acid differences from RRV-T48 were identified. Using fragment swapping and site-directed mutagenesis, we discovered that substitutions E402A and R522Q in nsP1 as well as Q619R in nsP2 were responsible for increased sensitivity of RRV 2548 to type I IFN. In contrast, substitutions A31T, N219T, S580L, and Q619R in nsP2 led to induction of higher levels of type I IFN. With exception of E402A, all these variations are common for naturally occurring RRV strains. However, they are different from all known determinants of type I IFN modulation reported previously in nsPs of alphaviruses. [ABSTRACT FROM AUTHOR]

Pelagic spawning riverine fish (pelagophils) spawn in free‐flowing river habitats with downstream drift of eggs and larvae but the spatial scale is often unknown, and this constitutes a major ecological knowledge gap.In the arid Darling River in south‐eastern Australia, the present objectives were: (i) to determine the potential downstream dispersal distance of young golden perch (Macquaria ambigua); and (ii) to evaluate whether provision of environmental water enhanced dispersal of young fish from Menindee Lakes to the lower Darling River (LDR) while also cueing further spawning in downstream lotic reaches.Golden perch spawned in unregulated lotic tributaries on a flood pulse and larvae drifted or dispersed >1,600 km downstream and entered large ephemeral productive floodplain lake nursery habitats as fully scaled fingerlings.Planned releases of environmental water cued golden perch spawning in the LDR and enabled juvenile fish to disperse downstream from the Menindee Lakes nursery into receiving populations in the LDR, Great Darling Anabranch, and southern Murray River, with some fish potentially completing an active migration of >2,100 km by age 1 year.The Darling River case study highlights the need for a system‐scale approach to the conservation management of pelagophilic fish, along with multi‐year perennial flow strategies to improve ecosystem integrity in large rivers globally. [ABSTRACT FROM AUTHOR]

In the summer and autumn of 2015, the Bellinger River snapping turtle (Myuchelys georgesi), a narrow‐range endemic of eastern New South Wales, Australia, suffered mass mortality from epidemic disease, apparently caused by a previously unknown virus. Information on the current population size and structure of M. georgesi, and the body condition and growth of the surviving individuals, is needed to support planning of conservation actions. Population estimates are also needed for a sympatric population of the widely distributed Macquarie turtle (Emydura macquarii), which has probably been introduced to the Bellinger River and may threaten the persistence of M. georgesi through hybridization, competition, and disease transmission.Data from five turtle surveys between November 2015 and November 2018 were used to estimate populations of the two species in the Bellinger River by an analysis based on habitat extent and turtle detectability. Changes in the body condition of M. georgesi and the body growth of both species were also assessed.Current populations of ~150 M. georgesi and ~500 E. macquarii are indicated, although the uncertainty of these estimates is high. The estimate for M. georgesi represents a decline of >90% from the historical population. Moreover, about 88% of the surviving M. georgesi are immature, and only about 5% are mature females. However, the body condition of the survivors has improved recently. Growth models suggest that M. georgesi matures later than E. macquarii, which may provide the latter with a competitive advantage.Evidence presented here does not support a previous hypothesis that M. georgesi were predisposed to disease through malnutrition and consequently reduced immune competence caused by high water temperatures and low river flows. Continuing disease, hybridization, and interspecific competition are probably the greatest threats to the persistence of the species. [ABSTRACT FROM AUTHOR]

The article presents a study which examined the effects of river runoff and related changes in naturally extreme environment by analyzing Porites coral from the macrotidal nearshore Kimberley region in Australia. Topics include the use of elemental (Ba/Ca) and isotopic compositions, observational coastal sea surface salinity, and geochemical time series in the study.

Hydrodynamic modelling is a powerful tool to gain understanding of river conditions. However, as widely known, models vary in terms of how they respond to changes and uncertainty in their input parameters. A hydrodynamic river model (MIKE HYDRO River) was developed and calibrated for a flood-prone tidal river located in South East Queensland, Australia. The model was calibrated using Manning's roughness coefficient for the normal dry and flood periods. The model performance was assessed by comparing observed and simulated water level, and estimating performance indices. Results indicated a satisfactory agreement between the observed and simulated results. The hydrodynamic modelling results revealed that the calibrated Manning's roughness coefficient ranged between 0.011 and 0.013. The impacts of tidal variation at the river mouth and the river discharge from upstream are the major driving force for the hydrodynamic process. To investigate the impacts of the boundary conditions, a new sensitivity analysis approach, based on adding stochastic terms (random noise) to the time series of boundary conditions, was conducted. The main purpose of such new sensitivity analysis was to impose changes in magnitude and time of boundary conditions randomly, which is more similar to the real and natural water level variations compared to impose constant changes of water level. In this new approach, the possible number of variations in simulated results was separately evaluated for both downstream and upstream boundaries under 5%, 10%, and 15% perturbation. The sensitivity analysis results revealed that in the river under study, the middle parts of the river were shown to be more sensitive to downstream boundary condition as maximum water level variations can reach 8%, 12%, and 15% under 5%, 10%, and 15% changes in the downstream boundary, respectively. The outcomes of the present paper will benefit future modelling efforts through provision of a robust tool to enable prediction of water levels at ungauged points of the river under various scenarios of flooding and climate change for the purpose of city planning and decision-making. [ABSTRACT FROM AUTHOR]

Documenting the processes that control the variations in stream geochemistry at different streamflows is important for being able to use chemical tracers to understand catchment functioning. The concentrations of most solutes, including reactive cations (e.g., Na, Ca, K, and Mg) and anions that are primarily derived from precipitation (Cl and Br), in five headwater streams from southeast Australia vary little with streamflow and are close to being chemostatic. By contrast, NO3 and SO4 concentrations are higher at high streamflows. There is also a systematic increase of 3H activities from as low as 1.1 to as high as 2.6 TU with increasing streamflow. The changes in geochemistry cannot be explained solely by increased mineral dissolution at high streamflows or enhanced baseflow driven by hydraulic loading. They are best explained by an increased baseflow input augmented by water mobilized from shallower stores as the catchments wet up. The mean transit times of the water sustaining streamflow varies from 35 to 70 years at low streamflows to <7 years at high streamflows. The use of a range of geochemical tracers, including radioactive isotopes, allows the different possible causes of chemostatic behaviour to be assessed and improves our understanding of catchment functioning. [ABSTRACT FROM AUTHOR]

Unit bars are relatively large bedforms that develop in rivers over a wide range of climatic regimes. Unit bars formed within the highly‐variable discharge Burdekin River in Queensland, Australia, were examined over three field campaigns between 2015 and 2017. These bars had complex internal structures, dominated by co‐sets of cross‐stratified and planar‐stratified sets. The cross‐stratified sets tended to down‐climb. The development of complex internal structures was primarily a result of three processes: (i) superimposed bedforms reworking the unit bar avalanche face; (ii) variable discharge triggering reactivation surfaces; and (iii) changes in bar growth direction induced by stage change. Internal structures varied along the length and across the width of unit bars. For the former, down‐climbing cross‐stratified sets tended to pass into single planar cross‐stratified deposits at the downstream end of emergent bars; such variation related to changes in fluvial conditions whilst bars were active. A hierarchy of six categories of fluvial unsteadiness is proposed, with these discussed in relation to their effects on unit bar (and dune) internal structure. Across‐deposit variation was caused by changes in superimposed bedform and bar character along bar crests; such changes related to the three‐dimensionality of the channel and bar geometry when bars were active. Variation in internal structure is likely to be more pronounced in unit bar deposits than in smaller bedform (for example, dune) deposits formed in the same river. This is because smaller bedforms are more easily washed out or modified by changing discharge conditions and their smaller dimensions restrict the variation in flow conditions that occur over their width. In regimes where unit bar deposits are well‐preserved, their architectural variability is a potential aid to their identification. This complex architecture also allows greater resolution in interpreting the conditions before and during bar initiation and development. [ABSTRACT FROM AUTHOR]

Understanding the modalities of aquatic species introductions is important in predicting and preventing new invasions. Australia's Pilbara Province is an arid region with no naturally occurring freshwater crayfishes. We assessed the population demographics and reproductive potential of redclaw crayfish (Cherax quadricarinatus) in Lake Poongkaliyarra, a major Pilbara water supply reservoir, in which public access and fishing are prohibited. We found the population to have a high relative abundance with a range of size-cohorts present. The species was believed to have first been introduced into the reservoir from at least 2010 and has subsequently been introduced and established in other lotic systems in the region, probably through deliberate releases from the lake for the purposes of providing fishing opportunities to areas where public access is permitted. Introductions of C. quadricarinatus in other parts of Australia and the world have also initially established in reservoirs before subsequently colonising natural systems. The study highlights the potential for reservoirs to act as primary stepping stones for invasion by freshwater crayfish. A self-maintaining population of redclaw crayfish is reported from a water supply reservoir in the Pilbara region in Western Australia. We suggest that reservoirs act as sources for invasion into rivers here and in other regions, and concerted management effort is required to halt the species' spread. [ABSTRACT FROM AUTHOR]

Rivers are a leading location for drowning, yet little is known about people's usage of these waterways. This pilot study aimed to test the use of direct observations to calculate river usage. Direct observations were conducted at regular intervals within defined zones at four river drowning locations in Australia (including weekends and the Australia Day national public holiday). Data recorded were date and time of observation; total people (including males, females, children, and adults); and number of people on, in, and beside the water. Univariate analysis with mean (SD) and range was conducted. Interrater reliability for observations was determined using the intraclass correlation coefficient (ICC) (one-way random-effects, average measures model), with a 95% confidence interval (CI). Across 149 time points, 309 observations resulted in 13,326 river interactions observed by multiple observers. There was an average of 39 people (M = 39.4, SD = 29.4, range = 0-137) per observation, 44 people (M = 44.2, SD = 32.7, range = 0-37) on an average weekend, and 97 people (M = 96.8, SD = 58.1, range = 20-190) on Australia Day. More females (M = 20.6, SD = 16.0, range = 0-83) than males (M = 18.3, SD = 14.5, range = 0-68) were observed. More people were observed in the water (M = 20.6, SD = 20.4, range = 0-84) than beside or on the water. Interrater reliability was excellent, consistently above 0.900 for all variables collected (apart from the variable of beside the river). Despite males accounting for 80% of river drowning fatalities, more females were observed than males. Increased visitation on the Australia Day public holiday may be linked to increased drowning risk. This study detailed a simple approach to data collection, exploring exposure within a defined zone at river locations. River usage is dynamic, with people's movement in and out of the water changing their risk exposure. Observational-based data collection for drowning, particularly for rivers, is an important yet highly neglected area of research. [ABSTRACT FROM AUTHOR]

Nerites (Gastropoda: Neritidae) are prominent members of tropical marine and freshwater gastropod faunas and rich assemblages can be found in many streams of islands in the Indo‐Pacific. For example, the streams of Fiji and New Guinea each support at least 23 species of freshwater neritimorphs, with representatives in the genera: Clithon, Neripteron, Neritilia, Neritina, Neritona, Neritodryas, Septaria, and Vittina.The striking diversity of this group in the small coastal streams of Pacific Islands contrast with a paucity of taxa in tropical Australia, despite northern Australia occupying a similar latitude. Just four taxa have been reported from Australia and only two can be considered common. These patterns are in marked contrast to the wide distribution of many marine nerites in the Pacific and conflicts with Island Biogeography Theory.Strikingly, many of these stream taxa have adopted an amphidromous lifestyle; adult gastropods feed and reproduce in freshwater, whereas larvae are swept to the ocean and undergo a marine dispersive phase before settling near the entrance to creeks and re‐entering these freshwater systems as crawling juveniles.Rapid transit of larvae to the ocean via short, steep, fast‐flowing streams may offer an explanation for this biogeographic conundrum. Larvae that do not reach the ocean within a few days may starve or exhibit poor survival. Hence, the disruption of stream–ocean connectivity may explain the low diversity of these taxa in northern Australia. Sea level rise in northern Australia in the current interglacial has further weakened stream–ocean connectivity with the development of vast flood plains and slow‐moving rivers.We contend that: (1) poor stream–ocean connectivity is not conducive to the maintenance of populations of nerites in northern Australia; and (2) new records of freshwater nerites may be revealed by surveys in short, steep coastal streams of northern Australia. [ABSTRACT FROM AUTHOR]

Historically, the differences in dispersal behaviour between individuals within a species has largely been ignored. Instead, we tend to assume all individuals within a population express similar phenotypes. However, evidence is growing for the importance of intraspecific variability in dispersal propensity and how this variability may influence population dynamics, as well as the role of environmental context in driving this behaviour. Individuals that are more likely to disperse can have other traits, such as being bolder or more aggressive, that collectively form behavioural syndromes. We tested for a behavioural syndrome in carp gudgeons (Hypseleotris spp.) species' complex, a type of small fish found in intermittent streams in southeastern Australia. Intermittent streams are an environment where selection may favour the evolution of different dispersal phenotypes, given the variable and unpredictable nature of flows. During dry periods, fish become isolated in refuge pools that vary in quality and persistence, and then can disperse when flow resumes. Dispersal can have costs (e.g. the risk of not finding another habitat) but also benefits (e.g. opportunity to find better habitat), meaning that different strategies (i.e. dispersing versus staying) may both be advantageous and thus evolve. Through a series of experiments that assessed these fish's latency to emergence into a novel environment and tendency to shoal, as well as movement behaviour in artificial streams, we found that (1) flow is not likely to be a movement cue, and (2) boldness, sociability and dispersal distance were repeatable, consistent with the notion that carp gudgeons exhibit personalities. To our knowledge, this is the first demonstration of a behavioural syndrome in a freshwater fish that inhabits intermittent streams. This finding contributes to our understanding of how carp gudgeons move through intermittent streams and the potential dynamics that allow these fish to persist in such harsh, hydrologically variable habitats. • We investigate if carp gudgeons from intermittent streams have dispersal syndromes. • Carp gudgeons did not use flow as a movement cue. • Boldness, sociability and movement distance were repeatable. • Our results are consistent with the notion that carp gudgeons exhibit personalities. [ABSTRACT FROM AUTHOR]

Invasive carp are widely reported to harm ecosystems. In Australia, carp are a serious pest and, consequently, investigations of biocontrol options are under way.Best practice biocontrol requires cost/risk:benefit evaluation. To assist this, the impacts of carp on aquatic ecosystems have been summarized.To aid the evaluation of benefits, general predictions were tested by comparing dryland river ecosystems with and without carp, and ecosystem responses to a gradient in local carp density.Expectations were that in the presence of carp, and with increasing density, there would be increasing turbidity, decreasing densities of macrophytes and macroinvertebrates, and associated changes in assemblage composition, resulting in decreasing native fish density.Not all expected responses were found, indicating that the general understanding of carp impact requires modification for dryland rivers. Notably, carp did not increase turbidity or reduce macroinvertebrate density or composition, probably because of key attributes of dryland rivers. In contrast, there were large impacts on native fish biomass, not from the mechanisms expected, but from food resource monopolization by carp. Macrophyte occurrence was reduced, but macrophytes are naturally rare in these rivers. It is likely that the extirpation of an endangered river snail resulted from carp predation.Impacts on native fish may be reversible by carp control, but reversal of impacts on the snail may require carp elimination and snail reintroduction. Modelling is necessary to predict the probability of beneficial versus undesirable outcomes from carp control, and complementary measures to control other stressors may be needed.Benefits of carp control on dryland river ecosystems are fewer than generally predicted. This reinforces the point that ecological understanding cannot always be transferred between diverse settings and highlights the need to understand system characteristics relevant to causal impact pathways when applying generic carp impact models to specific settings. This has global relevance to future carp control efforts. [ABSTRACT FROM AUTHOR]

The quandong or native peach (Santalum acuminatum R.Br.) has been recognised as an important and tasty food resource among Aboriginal Australians in arid and semi-arid areas of southern Australia. It is valued for its fruit that is consumed raw or dried, and for its kernel, which is eaten raw or ground into paste for medicinal and skin care purposes. This paper reports on a study of ground stone implements within the Murray Darling Basin that has identified quandong stones as a distinct type of implement made specifically for the efficient cracking of quandong nuts. Data are presented on 1,327 ground stone implements from collections in 12 different locations in the Murray-Darling Basin (MDB), an area almost completely devoid of stone sources. Given the paucity of stone, multi-purpose use of implements is widely documented. Although it was common to find pits present in mortars and other ground stone tools demonstrating multiple functions, including use as anvils, a class of single purpose stones with multiple pits and distinctive form was identified. Most of these were found in areas known for groves of quandong and four were analysed for use-wear and residues along with two other ground stone items from the MDB. The results support their identification as specialised anvil stones for cracking quandong nuts. [ABSTRACT FROM AUTHOR]

Practitioners of environmental water management (EWM) operate within complex social-ecological systems. We sought to better understand this complexity by investigating the management of environmental water for vegetation outcomes. We conducted an online survey to determine practitioners' perspectives on EWM for non-woody vegetation (NWV) in the Murray-Darling Basin, Australia with regards to: i) desirable outcomes and benefits; ii) influencing factors and risks; iii) challenges of monitoring and evaluation, and iv) improving outcomes. Survey participants indicated that EWM aims to achieve outcomes by improving or maintaining vegetation attributes and the functions and values these provide. Our study reveals that EWM practitioners perceive NWV management in a holistic and highly interconnected way. Numerous influencing factors as well as risks and challenges to achieving outcomes were identified by participants, including many unrelated to water. Survey responses highlighted six areas to improve EWM for NWV outcomes: (1) flow regimes, (2) vegetation attributes, (3) non-flow drivers, (4) management-governance considerations, (5) functions and values, and (6) monitoring, evaluation and research. These suggest a need for more than 'just water' when it comes to the restoration and management of NWV. Our findings indicate more integrated land-water governance and management is urgently required to address the impacts of non-flow drivers such as pest species, land-use change and climate change. The results also indicate that inherent complexity in EWM for ecological outcomes has been poorly addressed, with a need to tackle social-ecological constraints to improve EWM outcomes., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Cherie Campbell reports financial support was provided by Australian Government Research Training Program (RTP) Scholarship. Cherie Campbell reports financial support was provided by Australian Commonwealth Environmental Water Office (CEWO). Siwan Lovett reports a relationship with Australian River Restoration Centre that includes: employment. Samantha Capon reports a relationship with Eco Logical Australia Pty Ltd that includes: employment. Ross Thompson reports a relationship with Australian Commonwealth Environmental Water Office (CEWO) that includes: funding grants. Fiona Dyer reports a relationship with Australian Commonwealth Environmental Water Office (CEWO) that includes: funding grants. Siwan Lovett reports a relationship with Australian Commonwealth Environmental Water Office (CEWO) that includes: funding grants. All the authors have, over many years, received funding from various Australian government departments, such as the Murray Darling Basin Authority and the Commonwealth Environmental Water Office, to undertake river and wetland research, and to provide advice on technical issues and policy implications. Siwan Lovett is managing director of the not-for-profit Australian River Restoration Centre. Samantha J. Capon is a senior consultant with Eco Logical Australia Pty Ltd. Ross Thompson, Fiona Dyer and Siwan Lovett have all received funding from the Australian Commonwealth Environmental Water Office (CEWO) though not specifically in relation to this study., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Climate change is predicted to significantly alter hydrological cycles across the world, affecting runoff, streamflow, and pollutant loads from diffuse sources. The objectives of this study were to examine the impacts of climate change on streamflow, total nitrogen (TN), total phosphorus (TP), and total suspended sediment (TSS) loads in the subtropical Logan-Albert catchment, Queensland, Australia. We calibrated the Soil Water Assessment Tool (SWAT) against event monitoring data in the Logan and Albert rivers, respectively. Hydrological and water quality effects of an ensemble of 11 dynamically downscaled high-resolution climate models were assessed with SWAT under high (Representative Concentration Pathway 8.5 - RCP8.5) and intermediate (RCP4.5) emission scenarios. Streamflow decreased most in winter and spring and decreased least in summer. This followed the predicted seasonal changes for precipitation, although decreases tended to be amplified due to increasing evaporative loss. TSS, TN, and TP loads showed a similar pattern to streamflow, with the largest decreases predicted for the dry season under RCP8.5 by the 2080s. Annual TSS load decreased by 34.3 and 54.2%, TN load decreased by 29.8 and 30.5%, and TP load by 24.9 and 4.4% for the Logan and Albert sites, respectively. The results of this study indicate that for subtropical river-estuary systems, climate warming may lead to lower streamflow and contaminant loads, reduced flushing, and greater relative importance of point source loads in urbanising catchments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Creating and managing riparian buffer zones (RBZs) is regarded as a global best-practice management strategy for maintaining and improving waterway health. Agricultural land often utilises RBZs as highly productive pasture, exposing waterways to increased inputs of nutrients, pollutants, and sediment, in addition to reducing carbon sequestration and habitat for native flora and fauna. This project developed a novel approach to the application of multisystem ecological and economic quantification models to the property-scale, at low cost and high speed. We developed a state-of-the-art dynamic geospatial interface to communicate these outputs when switching from pasture to revegetated riparian zone via planned restoration efforts. The tool was developed using the regional conditions of a south-east Australian catchment as a case study but is designed to be adaptable around globally using equivalent model inputs. Ecological and economic outcomes were determined using existing methods, including an agricultural land suitability analysis to quantify primary production, an estimation of carbon sequestration using historic vegetation datasets and GIS software analysis to determine spatial costings of revegetation and fencing. Economic outcomes are presented in raw values of pasture produced and carbon sequestered, and fencing and revegetation costs can be easily altered for enhanced usability and interoperability. This tool can provide property-specific data for almost 16,000 properties in a catchment area of over 130,000 km 2 and 19,600 km of river length. Our results indicated that current financial incentives for revegetation rarely cover the cost of giving up pasture, but these costs may be compensated by social and ecological outcomes achieved over time. This method provides a novel way of informing alternative management approaches, such as incremental revegetation plans and the selective harvesting of timber from RBZ. The model provides an innovative framework for improved RBZ management and can be used to inform property-specific responses and guide discussion among stakeholders., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: James Malcher reports financial support was provided by River Basin Management Society., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Cholera is a major public health problem in developing and underdeveloped countries; however, it remains of concern to developed countries such as Australia as international travel-related or locally acquired cholera or diarrheal disease cases are still reported. Cholera is mainly caused by cholera toxin (CT) producing toxigenic O1 and O139 serogroup Vibrio cholerae strains. While most toxigenic V. cholerae cases in Australia are thought to be caused by international-acquired infections, Australia has its own indigenous toxigenic and non-toxigenic O1 and non-O1, non-O139 V. cholerae (NOVC) strains. In Australia, in the 1970s and again in 2012, it was reported that south-east Queensland riverways were a reservoir for toxigenic V. cholerae strains that were linked to local cases. Further surveillance on environmental reservoirs, such as riverways, has not been reported in the literature in the last 10 years. Here we present data from sites previously related to outbreaks and surveillance sampling to detect the presence of V. cholerae using PCR in conjunction with MALDI-TOF and whole-genome sequencing. In this study, we were able to detect NOVC at all 10 sites with all sites having toxigenic non-O1, non-O139 strains. Among 133 NOVC isolates, 22 were whole-genome sequenced and compared with previously sequenced Australian O1 and NOVC strains. None of the samples tested grew toxigenic or non-toxigenic O1 or O139, responsible for epidemic disease. Since NOVC can be pathogenic, continuous surveillance is required to assist in theclinical and envir rapid identification of sources of any outbreaks and to assist public health authorities in implementing control measures. IMPORTANCE Vibrio cholerae is a natural inhabitant of aquatic environments, both freshwater and seawater, in addition to its clinical significance as a causative agent of acute diarrhea and extraintestinal infections. Previously, both toxigenic and non-toxigenic, clinical, and environmental V. cholerae strains have been reported in Queensland, Australia. This study aimed to characterize recent surveillance of environmental NOVC strains isolated from Queensland River waterways to understand their virulence, antimicrobial resistance profile and to place genetic current V. cholerae strains from Australia in context with international strains. The findings from this study suggest the presence of unique toxigenic V. cholerae in Queensland river water systems that are of public health concern. Therefore, ongoing monitoring and genomic characterization of V. cholerae strains from the Queensland environment is important and would assist public health departments to track the source of cholera infection early and implement prevention strategies for future outbreaks. The genomics of environmental V. cholerae could assist us to understand the natural ecology and evolution of this bacterium in natural environments with respect to global warming and climate change., Competing Interests: The authors declare no conflict of interest.

Riverine floodplains are highly productive habitats that often act as nurseries for fish but are threatened by flow regulation. The Fitzroy River in northern Australia is facing development, but uncertainty exists regarding the extent to which floodplain habitats deliver benefits to fish, particularly given the brevity of seasonal floodplain inundation. We investigated the growth rate of young-of-year bony bream (Nematalosa erebi) in main channel and ephemeral floodplain habitats using age derived from otolith daily increments. We also investigated potential mechanisms influencing growth and modelled the consequences of differential growth rate on survival. Our results revealed higher growth occurred exclusively on the floodplain and that zooplankton biomass was the best predictor of growth rate. Modelling indicated that elevated growth rate in high-growth floodplain pools (top 25th percentile) could translate into substantial increases in survivorship. The positive effect of zooplankton biomass on growth was moderated under highly turbid conditions. Temperature had a minor influence on growth, and only in floodplain habitats. Our results indicate ephemeral floodplain habitats can deliver substantial growth and survival benefits to young-of-year fish even when floodplain inundation is brief. This study highlights the need to ensure that water policy safeguards floodplain habitats due to their important ecological role., (© 2023. Springer Nature Limited.)

Accurate river bathymetry is required for applications including hydrodynamic flow modelling and understanding morphological processes. Bathymetric measurements are typically a set of depths at discrete points that must be reconstructed into a continuous surface. A number of algorithms exist for this reconstruction, including spline-based techniques and kriging methods. A novel and efficient method is introduced to produce a co-ordinate system fitted to the river path suitable for bathymetric reconstructions. The method is based on numerical conformal mapping and can handle topological features such as islands and branches in the river. Bathymetric surfaces generated using interpolation over a conformal map are compared to spline-based and kriging methods on a section of the Balonne River, Australia. The results show that the conformal mapping algorithm produces reconstructions comparable in quality to existing methods, preserves flow-wise features and is relatively insensitive to the number of sample points, enabling faster data collection in the field. • Introduction of a new method for rapidly reconstructing river bathymetry from a set of point depth measurements. • Unlike some existing techniques, the method can handle complex river morphologies such as islands and branches. • The method only requires a set of depth points and a mask of the land and water areas, making it suitable for automation. [ABSTRACT FROM AUTHOR]