Globally, river regulation has degraded wetlands, including parts of the Murray-Darling Basin (MDB), an ecologically significant basin in Australia. Frogs in a floodplain environment largely depend on habitats created by river flows, but little is known about how frogs in the northern MDB are impacted by river regulation. We tested how wetland inundation affected frogs in a catchment of the northern MDB. We surveyed frogs between 2015 and 2019 to determine long-term changes in the community composition associated with wetland inun-dation from river flows. Additionally, we recorded nightly soundscapes for four days before and after the arrival of river flows between 2019 and 2020. The abundance and richness of frog species increased during larger inundation events leading to altered community composition (beta diversity). Warmer temperatures increased frog species richness, and frog community dominance decreased with decreasing vegetation cover (i.e., the relative abundance became more even across species). The abundance of five frog species (Limnodynastes tas-maniensis, Limnodynastes fletcheri, Crinia parinsignifera, Litoria peronii, and Litoria latopalmata) was higher in response to increased inundation extent. The total species richness of chorusing frogs increased after the arrival of river flows; six species chorused over the four nights preceding flow, whereas eight species chorused following the flow arrival, but the responses varied among species and sites. Frog species richness increased at three sites after flows, but not at others. After inundation, the choruses of Limnodynastes tasmaniensis increased whereas Limnodynastes fletcheri decreased. Our findings indicate that wetland inundation is beneficial for frog commu-nities and suggest that chorusing behaviour varied in response to river flows inundating floodplain wetlands.

Floodplain wetlands play a significant role in the storage of sediment and water and support high levels of nutrient cycling driven by intermittent inundation. In regulated rivers, the frequency and duration of floodplain inundation are often reduced. Managed water inundation is used as a tool to help restore floodplains, but its outcome on wetlands requires further quantification. We examined the effects of environmental floodplain watering on water quality and 3 groups of invertebrates, including benthic and pelagic microinvertebrates and macroinvertebrates, in 2 wetlands systems on the Gwydir River system in the north of the Murray-Darling Basin. We hypothesised that a wetland inundated for longer periods would alter water quality and support a greater richness and abundance of invertebrates, thus altering their assemblage structures. Water quality and the assemblage structure of all 3 invertebrate groups in the wetlands were significantly influenced by the time since connection (TSC) to their rivers and therefore the length of inundation. However, the response of water quality and the microinvertebrate assemblages to TSC differed between the 2 wetlands. Water quality was affected by an increase in 6 variables, including total nitrogen, and a decrease in soluble reactive phosphorus. Microinvertebrate abundance was positively associated with TSC, but the abundance of macroinvertebrates was not. The relationships demonstrated between TSC and invertebrates indicate that the duration of inundation is important for ecological structure and food webs in these and other semiarid floodplain wetlands.

Floodplain wetlands play a significant role in the storage of sediment and water and support high levels of nutrient cycling that lead to substantial primary production and high biodiversity. This storage, cycling and production system is driven by intermittent inundation. In regulated rivers the link between channel flows and floodplain inundation is often impacted with reduction in the frequency and duration of inundation. Managed floodplain inundation is us being used as a tool to help restore floodplain wetland processes and rehabilitate river systems. However, the use of managed water for the environment remains contentious and it is important to quantify the outcomes of re-introducing water to floodplain wetland systems. We examined the effects of environmental floodplain watering on water chemistry and three groups of invertebrates, including benthic and pelagic invertebrates and macroinvertebrates, in wetlands on the Gwydir River system in the north of the Murray-Darling Basin. We hypothesised that wetlands that were inundated for longer periods of time would have altered water chemistry and support a greater richness and abundance of invertebrates, thus altering their assemblage structures. Water chemistry and the assemblage structure of all three invertebrate groups in the wetlands was significantly influenced by the time since connection (TSC) to their respective rivers and therefore inundation period. The microinvertebrate abundance of was positively associated with TSC, but not macroinvertebrates. This suggests that the duration of connection between the channel and floodplain is important in maintaining the ecology and food webs in the wetlands.

The use of freshwater for human consumption and agriculture has resulted in many wetland ecosystems being some of the most seriously impacted ecosystems in the world. In attempts to rehabilitate wetland ecosystems environmental flows are used to restore parts of the hydrological regime altered by human water use. The use of environmental water intends to improve ecosystem health, but frequently aims to have specific outcomes for populations of higher-order consumers such as iconic fish and bird species. To date, research and monitoring has mainly focused on understanding 'flow-ecology' relationships, without investigating the mechanisms underlying them. We sought to understand the importance of different basal food sources to the growth of the endangered Murray cod in temporary wetland systems using fatty acid biomarkers. We flooded replicate mesocosms with two different wetland soils to produce sufficient zooplankton prey to sustain and grow Murray cod larvae for approximately 2 weeks. The fatty acid profiles of Murray cod and percentages of different biomarkers were compared at the start and finish of the experiment and our results suggest that the most important basal food source is green algae. However, the biomarkers of diatoms, cyanobacteria and bacteria also increased and differed between wetlands with different hydrological regimes. It is unclear if our results can be extended to other wetland systems and we encourage further research both into the relationship between length of wetland flooding and invertebrate densities in other systems. We also encourage research into the mechanistic pathways in which green algae carbon is transferred through food webs to higher order consumers in wetland systems to help generalise our results to other wetlands and support the management of wetlands through the timing and duration of flooding from environmental water.

Adaptive management is central to improving outcomes of environmental water delivery. The Australian Government's Murray−Darling Basin (MDB) Plan 2012 explicitly states that adaptive management should be applied in the planning, prioritisation and use of environmental water. A Long Term Intervention Monitoring (LTIM) program was established in 2014 to evaluate responses to environmental water delivery for seven Areas within the MDB, with evaluation also undertaken at the Basin scale. Adaptive management at the Area scale was assessed using two approaches: (a) through a reflective exercise undertaken by researchers, water managers and community members and (b) through an independent review and evaluation of the program, where relevant reports were reviewed and managers and researchers involved in the LTIM program were interviewed. Both assessment approaches revealed that the scale of management actions influenced the extent to which learnings were incorporated into subsequent actions. Although there were many examples where learnings within an Area had been used to adaptively manage subsequent environmental water deliveries within that Area, there was inconsistent documentation of the processes for incorporating learnings into decision making. Although this likely limited the sharing of learnings, there were also examples where learnings from one Area had influenced environmental water management in another, suggesting that sharing between concurrent projects can increase learning. The two assessments identified ways to improve and systematically document the adaptive management learnings . With improved processes to increase reflection, documentation and sharing of learnings across projects, there is an opportunity to improve management of environmental water and ecosystem outcomes.

The Murray-Darling Basin in south-eastern Australia contains over 70,000 km(2) of wetlands and floodplains, many of which are in poor condition. In response, Australian governments have committed to a major restoration program, the Murray-Darling Basin Plan that includes management of 2,750 Gl of environmental water to protect and restore aquatic ecosystems. The restoration is being undertaken within an adaptive management framework that includes monitoring the outcomes of environmental flows in seven river valleys. This paper provides an overview of the 5-year monitoring project and some preliminary results. Monitoring design considered the Basin Plan's environmental objectives, conceptual models of ecosystem responses to flow, and an outcomes framework linking flow responses to the environmental objectives. Monitoring indicators includes ecosystem type, vegetation, river metabolism, and fish. Responses are evaluated to identify the contribution of environmental flows to Basin Plan environmental objectives and continual improvements in management. The program is unique in that it seeks to monitor long-term outcomes of environmental flows at the river basin scale. Despite many challenges, the monitoring has become a key part of the adaptive management of environmental flows in the Murray-Darling Basin.

2019 Annual Forum presentation - overview of the research delivered over the five year EWKR project

Human activities are known to impact the physical template of river channels. These impacts can result from-deliberate, direct modifications as well as via indirect processes linked to broadscale landscape change. This study examined changes in the physical template of the Barwon-Darling River, a dryland river in southeastern Australia. Historical longitudinal profiles from the late 1800s were compared with contemporary profiles derived from high-definition, side scanning sonar. Comparisons focused on characterising waterhole features as they are a critical biophysical component of dryland rivers. The use of historical data presented several challenges related to small sample size and suspected sampling bias in the historical survey. However, this study demonstrates that these issues are not insurmountable providing the limitations and uncertainties with the data are acknowledged and data analyses are limited to parameters that can distinguish genuine landscape change. The findings revealed a dramatic change in the physical template of the Barwon-Darling River over a 120-yr period. Waterhole depths and distances between waterholes have been altered significantly. The magnitude and trajectory of change was found to be scale-dependent, with the greatest observable change aligned with the presence or absence of low-level weirs. Waterholes influenced by low-level weirs have increased in depth because of localised impoundment, whilst the distance between deep waterholes (>4 m in depth) has declined substantially. In contrast, the maximum depths of waterholes located outside the influence of weir pools has declined by 1.6 m and the distance between deep waterholes has more than doubled in several reaches. These declines are likely to be caused by sediment accumulation in waterholes associated with anthropogenic increases in sediment flux and a decline in the river's capacity to entrain and transport sediment throughout the system. (C) 2020 Elsevier B.V. All rights reserved.

Increasing demand for freshwater during the last century has so severely degraded many wetland ecosystems that they are some of the most seriously impacted environments in the world. Environmental flows are used as a management tool to restore parts of the hydrological regime altered by human water use, to rehabilitate these wetlands. Research and monitoring to date has focused on understanding 'flow-ecology' relationships, without investigating the mechanisms underlying them. We sought to understand how different basal food sources are incorporated into fish tissue in temporary wetland systems. This study provides a necessary first step toward the development of mechanistic research that investigates the effects of variation in fatty acids (FA) within the food and prey base on top predators. We added different sources of fatty acids to wetland mesocosms by adding extra food sources including redgum leachate to increase planktonic bacteria populations, cyanobacteria, green algae and biofilm matrix to observe how they were incorporated into secondary consumers. Wetland soil and water was added to replicate mesocosms, left for 28 days to produce zooplankton and then Western carp gudgeons added. There was a clear shift in the invertebrate assemblage structure following the introduction of the gudgeons. There was also a clear difference in assemblage structure and nutritional value between benthic and planktonic invertebrates. However, the addition of extra food sources did not generate differing FA profiles between treatments in the substratum fractions, invertebrates or fish after 14 days. We suggest that food sources generated within the mesocosms themselves may have outweighed any treatment effects. Using flooded wetland mesocosms potentially would have provided more realistic knowledge of the food web mechanisms of wetland inundation rather than feeding zooplankton fed specific primary food sources to fish. However, future experiments attempting to identify the mechanisms of the transfer of basal food sources in wetlands to secondary consumers may wish to directly feed fish primary consumers raised on specific basal food sources.

Floodplain wetlands are some of the most productive ecosystems available to aquatic and terrestrial organisms. However, regulation of lowland rivers can disrupt ecological processes occurring in the river–floodplain ecosystems, and environmental water can be delivered to affected wetlands to maintain productivity. It is not well understood at what stage following inundation there would be sufficient invertebrate biomass and large-sized individuals to support production and reproduction of secondary consumers. In this study we follow changes in the abundances of invertebrates after wetting in three mesocosm trials using soil from two wetlands from the north of the Murray–Darling Basin over 6-week periods. Peak abundances generally occurred in either the fifth or sixth weeks, but abundances were high after 2–3 weeks. Our results suggest that inundation of wetlands using environmental watering can achieve high productivity within a short time frame, within weeks. However, how quickly the high productivity is passed on to second-order consumers remains unclear and should be an area of future research.

Understanding energy flow through ecosystems and among sub‐habitats is critical for understanding patterns of biodiversity and ecosystem function. It can also be of considerable applied interest in situations where managing for connectivity among habitats is important for restoring degraded ecosystems. Here, we describe patterns of basal resource quality and identify primary basal energy sources in three habitats—river channels, anabranches and wetlands—of a lowland river floodplain in the Murray River catchment, Australia during a period of disconnected surface flow. We used a combination of stable isotope and fatty acid analyses to determine which basal resources were assimilated by the backswimmer Anisops thienemanni and the Eastern mosquitofish Gambusia holbrooki and assessed food quality across the three habitats. Seston was a primary basal resource for both animals in all three habitats, but was of higher quality within floodplain habitats than in the river channel. Although floodplain seston contained higher concentrations of essential fatty acids, fatty acid profiles of animals from different habitats remained similar. Our research suggests that inundation of floodplains and subsequent reconnection to the river could be valuable to afford riverine animals the opportunity to access high quality resources, but highlights a need to quantitatively assess the transfer of essential fatty acids between trophic levels to determine how much riverine animals are in fact limited by poorer quality food resources. We demonstrate the importance of estimating the quality of organic matter fluxes into food webs, and the potential role of targeted environmental flows to re‐establish high quality energy pathways in riverine ecosystems.

Aim We tested four hypotheses (a) that pioneer trees at distribution margins would receive fewer visits from pollinators and pollinator parasitoids than would trees in larger, established populations; (b) that predator release (lower rates of pollinator parasitism) would result in higher pollinator reproductive success; (c) that less competition among fewer pollinator foundresses would correlate with higher plant reproductive success and (d) that these effects would be greater at the plant species' expanding range margin. Location The dry, western side of the Great Dividing Range in northern New South Wales, eastern Australia. Taxon The rusty fig (Ficus rubiginosa, Moraceae), its pollinator and the pollinator's parasitoids. Methods We measured fruit (syconia) set per tree, seed set per syconium and fig-wasp numbers (pollinators and non-pollinators) per syconium in a total of 62 trees in 24 populations covering three distributional zones - the dry, western margin of the species' range, a more mesic, eastern margin at the species' altitudinal limit, and the zone between these two margins. These results were modelled against F. rubiginosa population size, the position of plant populations in relation to range margins, and climatic gradients of temperature and rainfall. Results Lower rates of pollinator parasitism and less pollinator competition correlated with increased reproductive success in the pollinator and increased male fitness (in terms of pollen dispersal) and female fitness (in terms of seed per syconium) in isolated trees of F. rubiginosa, compared with trees in larger populations, particularly at F. rubiginosa's mesic, expanding range margin. Main Conclusions Pollinator-predator release and pollinator-competition release can lead to increased pollinator and plant reproductive success in pioneer trees at range margins. This reinforces the need to understand biotic interactions underlying reproduction and dispersal at expanding range fronts if we are to understand and better predict the drivers and effects of climate-change-induced range shifts in plants and their pollinators.

Multifunctional landscapes provide multiple ecosystem services and are managed collaboratively to preserve biodiversity and ecosystem function and support human wellbeing. Linking ecological patterns across systems is essential to advance ecosystem services research and inform ecologically-sustainable landscape management. Network theory provides a robust, accessible framework to build knowledge of ecosystem services, engage with stakeholders, and link disciplinary knowledge and system processes across multiple scales. But two major knowledge gaps need to be overcome to facilitate a unified framework for quantifying ecosystem services via integrated social, ecological and economic networks: (i) methods to link social actors with biodiversity and ecosystem function across different systems (terrestrial—aquatic and social—ecological); and (ii) a simple ecosystem services network typology that is relevant across disciplines and systems, and is accessible to practitioners. We advocate an interdisciplinary approach to ecosystem services networks that is grounded in ecological theory. Research and practice should prioritise understanding critical connections between systems, particularly terrestrial—aquatic energy flows and relationships between biodiversity, ecosystem function and human wellbeing.

A growing body of evidence suggests that dams intensify malaria transmission in sub-Saharan Africa. However, the environmental characteristics underpinning patterns in malaria transmission around dams are poorly understood. This study investigated local-scale environmental and meteorological variables linked to malaria transmission around three large dams in Ethiopia.

This study investigated how changes in reservoir water level affect mosquito abundance and malaria transmission in Ethiopia. Digital elevation models of three Ethiopian dams at lowland, midland and highland elevations were used to quantify water surface area and wetted shoreline at different reservoir water levels (70, 75, 80, 85, 90, 95 and 100% full capacity) to estimate surface area of potential mosquito breeding habitat. Reservoir water level drawdown rates of 10, 15 and 20 mm.day−1 were applied as scenarios to model larval abundance, entomological inoculation rate (EIR) and malaria prevalence at each dam. Malaria treatment cost and economic cost in terms of lost working days were calculated for each water level scenario and dam. At the lowland dam, increased larval abundances were associated with increasing reservoir water level and wetted shoreline area. In contrast, both larval abundances and area of wetted shoreline declined with increasing reservoir water level at the midland and highland dams. Estimated EIR, malaria prevalence, malaria treatment cost and economic cost generally decreased when the water level drawdown rate increased from 10 to 15 and 20 mm.day−1 irrespective of reservoir water level. Given the expansion of dam construction in sub-Saharan Africa, incorporating malaria control measures such as manipulating drawdown rates into reservoir management has the potential to reduce the malaria burden and health care costs in communities near reservoirs.

Background Water level management has been suggested as a potential tool to reduce malaria around large reservoirs. However, no field-based test has been conducted to assess the effect of water level management on mosquito larval abundance in African settings. The objective of the present study is to evaluate the effects of water level drawdown rates on mosquito larval abundance. Methods Twelve experimental dams were constructed on the foreshore of the Koka Dam in Ethiopia. These were grouped into four daily water drawdown treatments, each with three replicates: no water-level drawdown (Group 1; Control), 10 mm.d-1 (Group 2), 15 mm.d-1 (Group 3) and 20 mm.d-1 (Group 4). Larval sampling was conducted weekly for a period of 6 weeks each in the main malaria transmission season (October to November 2013) and subsequent dry season (February to March 2014). Larval densities were compared among treatments over time using repeated measures Analysis of Variance (ANOVA). Results A total of 284 Anopheles mosquito larvae were collected from the experimental dams during the study period. Most (63.4%; n = 180) were collected during the main malaria transmission season while the remaining (36.6%; n = 104) were collected during the dry season. Larvae comprised four Anopheles species, dominated by Anopheles arabiensis (48.1% of total larval samples; n = 136) and An. pharoensis (33.2%; n = 94). Mean larval density was highest in control treatment dams with stable water levels throughout the study, and decreased significantly (P < 0.05) with increasing water drawdown rates in both seasons. During the main transmission season, anopheline larval density was generally lower by 30%, 70% and 84% in Groups 2, Group 3 and Group 4, respectively, compared with the control dams (Group 1). In the dry season, larval density was reduced by 45%, 70% and 84% in Groups 2, Group 3 and Group 4, respectively, when compared to the control dams. Conclusion Increased water drawdown rates were associated with lower mosquito larval abundance. Water level management could thus serve as a potential control measure for malaria vectors around reservoirs by regulating the persistence of shallow shoreline breeding habitats. Dam operators and water resource managers should consider incorporating water level management as a malaria control mechanism into routine dam operations to manage the risk of malaria transmission to human populations around reservoirs.

This special issue of Ecological Management and Restoration contains nine papers based on invited presentations at Restore, Regenerate, Revegetate: A Conference on Restoring Ecological Processes, Ecosystems and Landscapes in a Changing World, held at the University of New England from 5–9 February 2017 (Box 1). The issue provides a timely overview of some of the achievements as well as the major challenges facing ecosystem restoration in Australasia. The role of the arts in communicating environmental messages was explored through performance, artworks and a public forum – and field trips were arranged for delegates to visit local restoration projects and meet practitioners. An additional selection of papers based on the plenary and keynote addresses from the conference was published recently in a special issue of The Rangeland Journal (see http://www.publish.csiro.au/RJ/issue/8600/). The audio recordings of most of the conference presentations as well as the conference proceedings containing a further 44 refereed papers can be found at http://www.une.edu.au/about-une/academic-schools/school-of-environmental-and-rural-science/ers-news-and-events/restore-regenerate-revegetate-conference-2017. In his opening comment piece, David Freudenberger discusses the mismatch between the scale of restoration required in Australia and what has been being achieved to date. He notes the potential for farmers to restore the long-term productivity, resilience and economic viability of their farms through revegetation, and the need for a massive increase in expenditure to underpin the required investment in broad-scale restoration. Reviewing funding of land repair over the last three decades, and noting that the Natural Heritage Trust that was created by the part-sale of Telstra in 1997 ceased in 2008, he advocates the creation of a permanent trust, funded perhaps by the royalties generated from mining or a price on carbon pollution, and a partnership with agricultural industries to repair and protect natural capital. Paul Gibson-Roy issues a similar call-to-arms to Australian restoration practitioners, researchers and politicians about the required scale of restoration of grassy ecosystems in southern and eastern Australia. He contrasts the domestic situation with revelations from a recent Churchill Fellowship-funded tour of herbaceous seed production and revegetation infrastructure in the United States. He highlights the degree of regulatory support and government investment in the native wildflower and grass seed restoration industry over several decades and the pivotal role of successive US presidents on both sides of politics from Presidents Roosevelt to Obama in underwriting the expenditure. Australians would do well to demand a similar calibre of leadership here. David Norton and colleagues provide a New Zealand perspective on upscaling ecological restoration for biodiversity conservation in their feature article. They highlight eight important lessons that need to be incorporated in restoration planning to increase the likelihood of success. With new government-led revegetation initiatives announced recently, their feature article is not only timely to assist nurseries, restoration practitioners, community groups, and government and nongovernment organisations for upscaling New Zealand restoration, but relevant to recovering and reconnecting natural ecosystems at scale and improving the prospects for biodiversity everywhere. David Lindenmayer and colleagues outline ten lessons from a 20-year-long research programme on fauna–habitat dynamics in the wheat–sheep belt in south-eastern Australia, and the implications for woodland restoration and habitat management in agricultural landscapes. The authors stress the complementary role of different habitats (plantings, regrowth, old growth, linear remnants, etc.) as habitat for fauna, including species of conservation concern, and the importance of carefully designed, long-term monitoring. They also highlight the human dimension associated with farmland restoration and management, and argue for further research on the important nexus between environmental management, farm profitability and sustainability, and farmer health and well-being. In their commissioned review, Sam Capon and Neil Pettit advocate a functional approach to planning and prioritising riparian restoration based on measurable targets and a broad consideration of spatiotemporal and cultural influences. They summarise the main anthropogenic threats to river functions and recommend practical solutions for robust riparian restoration. As an example, passive regeneration of novel ecosystems may maintain and restore riparian functions and services in agricultural and urban catchments where native riparian vegetation is sparse and the slowing and filtering of runoff important. The authors highlight policy and management directions, including the need for evidence-based decision making by institutions guided by the principles of social justice and adaptive management. In another commissioned review, Carla Catterall reminds us that the ecological processes that maintain or restore ecosystem health and integrity of forests and woodlands involve animal–plant interactions, yet fauna are often an afterthought in restoration. She comments that animals have often been viewed as passengers, responding passively to plant-focused revegetation. Yet fauna can drive plant recruitment processes in farmland restoration (e.g. through seed dispersal) and determine the floristic diversity and composition of revegetation. Although functionally important animals can accelerate woody vegetation restoration through various ecological mechanisms, research is needed to clarify the roles of animals as passengers vs drivers of restoration to develop a more predictive science. Rhiannon Smith and Andrew Watson demonstrate the economic benefits from the environmental approaches implemented by successive generations of Watsons in managing the family farm, ‘Kilmarnock’, on the banks of the Namoi River at Boggabri, New South Wales. Farm income is dominated by irrigated cotton production, and monitoring of on-farm trials over the past 10–15 years have revealed both positive economic and ecological outcomes from several innovations. The advent of genetically modified cotton has allowed insecticide use to be minimised in favour of habitat provision for natural pest control agents (beneficial invertebrates, microbats and insectivorous birds) through farmland revegetation and habitat restoration. Benefits have also accrued from substituting poultry manure for chemical fertilisers and water-use efficiency improvements. Martine Maron and Winnifred Louis argue for greater transparency around restoration funding when sourced from offsets, because the volunteers who undertake a considerable amount of the restoration work in Australia are often not aware that the net environmental outcome of offset-funded restoration is neutral (at best), not environmental gain. If restoration for a mandated offset is undertaken by volunteers, their contribution simply substitutes for work that would otherwise have been done commercially. In effect, the volunteer subsidy distorts the true replacement cost of biodiversity. All environmental nongovernmental organisations, developers, offset funders and brokers should commit to transparency, particularly to landholders, donors and volunteers who donate land, money and labour to restoration, about the environmental impact that is to be offset and the fact that volunteer involvement generates no additional environmental benefit. In the final feature article, Tein McDonald and Kingsley Dixon discuss two of the key principles in the recently published 2nd edition of the National Restoration Standards. They clarify the concepts of reference ecosystem and the required degree of recovery for ecological restoration. It is not about trying to restore a past state per se but about reinstating what would be the current local native ecosystem had it not been degraded, taking anticipated environmental change into account. However, in the event of irreversible environmental change, restoration of altered or completely different local species assemblages better suited to the new conditions may be appropriate. Ecological restoration is also directed towards full recovery ‘insofar as possible’, acknowledging that at times something less than full recovery of the most appropriate local reference ecosystem may be all that can be achieved. The delegates at the Restore, Regenerate, Revegetate Conference held at the University of New England, Armidale, New South Wales, from 5–9 February 2017, shared an impressive body of practical and scientific knowledge of how we are restoring Australia's natural heritage and environmental capital across the continent. However, the conference also highlighted several key points that must be addressed if we are to truly meet the challenges and opportunities of land repair. We commend the papers in this special issue to a wide audience and trust that they command as much interest and satisfaction as we derived from working with our guest authors in preparing them for publication. Nick Reid is Professor in Ecosystem Management and Head, School of Environmental and Rural Science, University of New England (Armidale, NSW 2351, Australia; Email: nrei3@une.edu.au). Rhiannon Smith is Research Fellow and Lecturer, Ecosystem Management, School of Environmental and Rural Science, UNE (Armidale, NSW 2351, Australia; Email: rsmith66@une.edu.au). Wal Whalley is Adjunct Associate Professor in Botany, School of Environmental and Rural Science, UNE (Armidale, NSW 2351, Australia; Email: rwhalley@une.edu.au). David A. Norton is Professor, School of Forestry, University of Canterbury (Private Bag 4800, Christchurch 8140, New Zealand; Email: david.norton@canterbury.ac.nz). Darren Ryder is Professor and Associate Dean Teaching and Learning, Faculty of Science, Agriculture, Business and Law, UNE (Armidale NSW, 2351, Australia; Email: dryder2@une.edu.au)

Of all ecosystems, freshwaters support the most dynamic and highly concentrated biodiversity on Earth. These attributes of freshwater biodiversity along with increasing demand for water mean that these systems serve as significant models to understand drivers of global biodiversity change. Freshwater biodiversity changes are often attributed to hydrological alteration by water-resource development and climate change owing to the role of the hydrological regime of rivers, wetlands and floodplains affecting patterns of biodiversity. However, a major gap remains in conceptualising how the hydrological regime determines patterns in biodiversity’s multiple spatial components and facets (taxonomic, functional and phylogenetic). We synthesised primary evidence of freshwater biodiversity responses to natural hydrological regimes to determine how distinct ecohydrological mechanisms affect freshwater biodiversity at local, landscape and regional spatial scales. Hydrological connectivity influences local and landscape biodiversity, yet responses vary depending on spatial scale. Biodiversity at local scales is generally positively associated with increasing connectivity whereas landscape-scale biodiversity is greater with increasing fragmentation among locations. The effects of hydrological disturbance on freshwater biodiversity are variable at separate spatial scales and depend on disturbance frequency and history and organism characteristics. The role of hydrology in determining habitat for freshwater biodiversity also depends on spatial scaling. At local scales, persistence, stability and size of habitat each contribute to patterns of freshwater biodiversity yet the responses are variable across the organism groups that constitute overall freshwater biodiversity. We present a conceptual model to unite the effects of different ecohydrological mechanisms on freshwater biodiversity across spatial scales, and develop four principles for applying a multi-scaled understanding of freshwater biodiversity responses to hydrological regimes. The protection and restoration of freshwater biodiversity is both a fundamental justification and a central goal of environmental water allocation worldwide. Clearer integration of concepts of spatial scaling in the context of understanding impacts of hydrological regimes on biodiversity will increase uptake of evidence into environmental flow implementation, identify suitable biodiversity targets responsive to hydrological change or restoration, and identify and manage risks of environmental flows contributing to biodiversity decline.