Abstract
1. Global pressures on freshwater ecosystems are high and rising. Viewed primarily as a resource for humans, current practices of water use have led to catastrophic declines in freshwater species and the degradation of freshwater ecosystems, including their genetic and functional diversity. Approximately three-quarters of the world's inland wetlands have been lost, one-third of the 28 000 freshwater species assessed for the International Union for Conservation of Nature (IUCN)
Abstract
Red List are threatened with extinction, and freshwater vertebrate populations are undergoing declines that are more rapid than those of terrestrial and marine species. This global loss continues unchecked, despite the importance of freshwater ecosystems as a source of clean water, food, livelihoods, recreation, and inspiration.
Abstract
2. The causes of these declines include hydrological alterations, habitat degradation and loss, overexploitation, invasive species, pollution, and the multiple impacts of climate change. Although there are policy initiatives that aim to protect freshwater life, these are rarely implemented with sufficient conviction and enforcement. Policies that focus on the development and management of fresh waters as a resource for people almost universally neglect the biodiversity that they contain.
Abstract
3. Here we introduce the Alliance for Freshwater Life, a global initiative, uniting specialists in research, data synthesis, conservation, education and outreach, and policymaking. This expert network aims to provide the critical mass required for the effective representation of freshwater biodiversity at policy meetings, to develop solutions balancing the needs of development and conservation, and to better convey the important role freshwater ecosystems play in human well-being.
Abstract
Through this united effort we hope to reverse this tide of loss and decline in freshwater biodiversity. We introduce several short-and medium-term actions as examples for making positive change, and invite individuals, organizations, authorities, and governments to join the Alliance for Freshwater Life.
| INTRODUCTION
Freshwater ecosystems are a fundamental resource for human life, providing clean water, food, livelihoods, and other ecosystem services, estimated to be worth over $4 trillion annually (Béné et al., 2016; Costanza et al., 2014; Lynch et al., 2016; Youn et al., 2014) . The rivers, lakes, and wetlands that make up these ecosystems cover less than 1% of the Earth's surface area (Mittermeier, Farrell, Harrison, Upgren, & Brooks, 2010) , and yet support over 10% of all known species (Dijkstra, Monaghan, & Pauls, 2014; Mittermeier et al., 2010) , including 30% of all vertebrates.
| INTRODUCTION
Despite the overwhelming contribution of fresh waters to global biodiversity and human well-being, there is, simply put, a global freshwater biodiversity crisis that requires immediate attention. Freshwater vertebrate populations have declined by more than 80% over the past 50 years, a rate of decline twice that recorded for either marine or terrestrial systems (World Wide Fund for Nature, WWF, 2016) . According to the International Union for Conservation of Nature (IUCN, 2017) , approximately one in three of the 28 000 species dependent upon freshwater habitats thus far assessed is threatened with extinction. An estimated three-quarters of the world's inland natural wetlands were lost during the 20 th century (Davidson, 2014) . The World Economic Forum (WEF) report for 2017 ranks freshwater supply at number three in a list of the top-10 global risks in terms of impact, surpassed only by weapons of mass destruction and extreme weather events (WEF, 2017) .
| CAUSES OF THE FRESHWATER BIODIVERSITY CRISIS
The causes of this crisis have been recognized for many years (Abell, 2002; Benz & Collins, 1997; Collen et al., 2014; Dudgeon et al., 2006; Foley et al., 2005; Master, Stein, Kutner, & Hammerson, 2000; McAllister, Hamilton, & Harvey, 1997; Strayer & Dudgeon, 2010; Thieme et al., 2011; Vörösmarty et al., 2010 ), yet little action has been taken to address them. A fundamental driver of the decline in freshwater biodiversity is the dramatic increase in global consumption of natural resources over the last century (Garcia-Moreno et al., 2014) . This has led to unsustainable water abstraction, widespread habitat loss and degradation, increased levels of pollution, and a proliferation of invasive species (Garrick et al., 2017) . Many wetlands have been converted to agricultural production (Ramsar, 2017) , and other fresh waters are actively used as sinks for pollutants or dumps for effluent and industrial waste, without consideration of the harm caused or the resultant loss of biodiversity and ecosystem functioning in these systems (Craig et al., 2017) . Engineering-based solutions for water provisioning emphasize water infrastructure (Green et al., 2015; Note: With the exception of the primary author, the order of authorship is alphabetical. Bernhardt, Koska, & Zarfl, 2016; Vörösmarty et al., 2010) . These may help meet human demands for water in the short term, but often have significant impacts on freshwater ecosystems .
| CAUSES OF THE FRESHWATER BIODIVERSITY CRISIS
Changes in precipitation and temperature regimes linked to climate change greatly compound these impacts (Tedesco et al., 2013) .
| CAUSES OF THE FRESHWATER BIODIVERSITY CRISIS
This demand for fresh water will only increase in the current epoch of rapid environmental change, termed the Anthropocene (Crutzen & Stoermer, 2000; Waters et al., 2016) . Around 750 million people still lack access to safe drinking water, and more than 1.3 billion people lack access to electricity, for which hydropower is still viewed as a solution (World Health Organization/United Nations Children's Fund (WHO/ UNICEF), 2015). Agriculture currently accounts for 70% of freshwater use globally. By 2050, agricultural production will need to increase by 60% globally, and will need to double in developing countries (Alexandratos & Bruinsma, 2012) or be exported from those parts of the world gearing up to increase their share of global markets. Water demand for manufacturing is expected to increase by 400% between 2000 and 2050 globally (United Nations World Water Assessment Programme (WWAP), 2015). It is predicted that by 2030 the average global water requirements will exceed current accessible and reliable water supplies by over 40% (Addams, Boccaletti, Kerlin, & Stuchtey, 2009) .
| CAUSES OF THE FRESHWATER BIODIVERSITY CRISIS
A second fundamental cause for the freshwater biodiversity crisis is the insufficient consideration of impacts on freshwater ecosystems in decision making and policy about water and land use, leading to their degradation and loss (Cowx & Portocarrero Aya, 2011; Garrick et al., 2017; Hoekstra & Mekonnen, 2012) . Safeguarding freshwater ecosystems often comes second to other development priorities that are viewed as being more directly linked to human well-being, such as the provision of drinking water, energy, and food. The result is the unnecessary and often inadvertent sacrifice of freshwater life as collateral damage in global development, which can lead to the destruction of the very ecosystems required to support these same objectives. One example is the loss of food production through the destruction of freshwater fisheries (Lynch et al., 2017) . Another is the global surge in hydropower projects (Zarfl, Lumsdon, Berlekamp, Tydecks, & Tockner, 2015) , viewed as a 'green' energy source despite the extensive degradation of habitat and the disruption of species migration routes (Winemiller et al., 2016) . The UN High Level Panel on Water recognizes the value of the environment in delivering water-related services to people, but is (very nearly) silent on biodiversity and non-human uses of water (https://sustainabledevelopment. un.org/HLPWater). We consider this to be an example of an anachronistic approach to policymaking that can be changed through coordinated and sustained global actions.
| CAUSES OF THE FRESHWATER BIODIVERSITY CRISIS
There are a number of international agreements to conserve and support the sustainable use of freshwater species and ecosystems, including the Convention on Biological Diversity (CBD; with 168 signatory countries at the time of writing) (Leadley et al., 2014) and the Ramsar Convention on Wetlands of International Importance (www.ramsar.org). More recently agreed, the Sustainable Development Goals (SDGs) (https://sustainabledevelopment.un.org/), to which almost all countries are committed, are intended to promote prosperity while protecting the planet. The SDGs include targets to protect and restore water-related ecosystems (Target 6.1); to ensure the conservation, restoration, and sustainable use of terrestrial and inland freshwater ecosystems, and their services (Target 15.1); and to reduce the degradation of natural habitats, halt the loss of biodiversity, and protect and prevent the extinction of threatened species (Target 15.5).
| CAUSES OF THE FRESHWATER BIODIVERSITY CRISIS
The targets are for delivery in 2030 (6.1) or, alarmingly, as early as 2020 (15.1 and 15.5). If progress is not adequate, the targets risk being discounted as unrealistic or impractical. It is therefore imperative that efforts are stepped up to achieve these targets. In short, international efforts thus far lack specific actions and goals for conserving freshwater ecosystems and species, and their genetic and functional diversity. As a result, they have had little success in slowing their decline (Convention on Biological Diversity, 2014). It is only through galvanizing, massively expanding, and mobilizing the currently fragmented network of experts working to improve our understanding and conservation of freshwater ecosystems that we will gain the voice and momentum required to influence, inform, and help implement existing and new policy for the benefit of freshwater biodiversity. It is also through this alliance that we will generate a detailed road map for change to conserve and benefit from freshwater biodiversity in the future.
| CAUSES OF THE FRESHWATER BIODIVERSITY CRISIS
Although the challenges may appear insurmountable, there have been successes upon which to model a more positive future, in which human needs are met and biodiversity loss is minimized. There have been successes in restoring rivers and wetlands, improving connectivity for migrating fish, and challenging inappropriate hydropower developments and unsustainable water abstraction and pollution. We see the beginnings of a global movement to halt and reverse the current declines in freshwater biodiversity, and an increasing awareness in the global population of the need for better water and land-use practices. To date, however, these actions have been few and far between, carried out in relative isolation, and are wholly insufficient in the context of the freshwater biodiversity crisis. We feel that it is time for the global freshwater biodiversity community to unite, to coordinate our actions, and to help civil societies and governments take action on a scale appropriate to the magnitude of this crisis. We need to improve awareness of the issues, provide the necessary scientific research to inform environmental and development decision making, engage with policymakers to help set priorities for biodiversity with respect to human concerns, and effectively exchange information between science, policy, and management.
| CAUSES OF THE FRESHWATER BIODIVERSITY CRISIS
A major shift in our approach to water and land management is required to address the continuing freshwater biodiversity crisis. Dudley, Harrison, Kettunen, Madgwick, and Mauerhofer (2016) noted that key activities needed for the improved conservation of freshwater ecosystems included: the development of better partnerships across sectors to promote conservation and management; closer attention to the role of natural infrastructure in freshwater resource management; an increase in knowledge and capacity-building within the sectors addressing freshwater conservation; the improved development of policy frameworks; and a process of learning lessons from successful water management (e.g. the development of 'conservation evidence'). It is encouraging to see that the substantial value of nature-based solutions (NBSs) is becoming more widely recognized as a way to offset the rising challenges to water security while also addressing the continuing decline in freshwater biodiversity (WWAP, 2018). However, investment in NBS options is still below 1% of the total investment in water resources management infrastructure (WWAP, 2018).
| THE ALLIANCE FOR FRESHWATER LIFE AND ITS FIVE CORE AREAS FOR ACTION
In response to the present and future challenges, we introduce here the formation of a global initiative, the Alliance for Freshwater Life (hereafter referred to as the Alliance) (https://allianceforfreshwaterlife.org). The We have thus far identified five core areas of work as being essential to support stakeholders in halting and reversing the loss of freshwater biodiversity (Figure 1) . These areas of work will not, on their own, bring the changes required for freshwater biodiversity to be restored and conserved for the future. It is only through their integration, combined with serious consideration of freshwater biodiversity needs in the decision making by the public and private sectors, conservation non-governmental organizations (NGOs), and international conventions dedicated to nature conservation, that the necessary change will occur at a global scale.
| THE ALLIANCE FOR FRESHWATER LIFE AND ITS FIVE CORE AREAS FOR ACTION
The Alliance has been formed to facilitate this integration of expertise and capacity, and to stimulate a new momentum to effect change.
| Research
Scientific research is essential to inform good conservation decision making and for establishing the socio-economic context for sustainable use (Bhaduri et al., 2016; Matthews, Wickel, & Freeman, 2011) . The Alliance aims to improve our understanding of all facets of freshwater biodiversity. All too often the application of academic research to further our understanding of freshwater ecosystems, give direction on appropriate conservation action, and inform national or international policy is not realized effectively. Major gaps in knowledge need to be identified and addressed, particularly on the distribution and status of freshwater biodiversity, how freshwater biodiversity could be better integrated into the landscapes of the Anthropocene, and which data and knowledge are needed to balance human needs with sustaining biodiversity. The potential application of existing and continuing research will be identified and communicated as part of the awareness-raising activities. Support for filling knowledge gaps, resulting in large part from the, often limited, funding for freshwater biodiversity conservation and research, will be addressed through a coordinated large-scale funding drive.
| Research
The Alliance will engage with some of the world's largest freshwater research organizations to ensure the greater application of existing research, and to identify and fill existing gaps in knowledge essential to conservation and sustainable use of freshwater biodiversity.
| Data and synthesis
Although data and knowledge relevant to the management and conservation of freshwater biodiversity are available, they are not often easily or freely accessed, or presented in a consistent or integrated
| Data and synthesis
way. An objective of the Alliance is to make this body of existing information more readily and openly available in a suitable format for conservation decision makers, managers, researchers, and other interested parties. We will build upon and support existing global initiatives, such as the Freshwater Information Platform (www. freshwaterplatform.eu), the IUCN Red List of Threatened Species (www.iucnredlist.org), the World Database of Key Biodiversity Areas (www.keybiodiversityareas.org), the Global Lake Ecological Observatory Network (www.gleon.org), and the Freshwater Biodiversity Observation Network (FWBON, geobon.org/networks/thematicbon/freshwater-bon), in the development and application of essential biodiversity variables for tracking change in freshwater biodiversity (Turak et al., 2017) . Through these actions the Alliance aims for data FIGURE 1 The five core areas of work under the Alliance for Freshwater Life transparency and will help to expand open access to information, making it more readily available to all interested parties.
| Conservation
Conservation and the sustainable use of freshwater biodiversity is the backbone of the Alliance. Its policy mandate is closely linked to demands from national governments, the Ramsar and CBD conventions, and the SDGs, as well as those for delivering knowledge usable for the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). Freshwater biodiversity requires conservation management on the ground, such as to restore the species and ecosystems that are already degraded, to ensure that their use is sustainable, and to identify and protect those that remain in relatively good condition.
| Conservation
The Alliance will help conservation activists, scientists, policy makers, and funding organizations to collaborate and share knowledge on conservation actions. This global social network and community of practice for freshwater biodiversity conservation includes worldrenowned leaders in their fields, as well as major partner organizations working to conserve freshwater biodiversity. The global network of organizations and experts will support the sharing and dissemination of information and technology for biodiversity management, conservation, and observation. The Alliance will work to develop new projects and partnerships to implement large-scale conservation actions.
| Education and outreach
Levels of awareness of the biodiversity crisis in freshwater ecosystems remain pitifully low, and prompted Richter, Braun, Mendelson, and Master (1997) to refer to threats to freshwater biodiversity as the 'quiet crisis … taking place beneath the surface of the world's rivers and lakes'. This situation remains largely unchanged (Dudgeon, 2010) , and thus requires large-scale initiatives that bring a focus and a voice to freshwater biodiversity. Initiatives such as Ramsar's 'World Wetland Day' (www.worldwetlandsday.org), the 
| Policy
Environmental policies rarely include specific targets to benefit freshwater biodiversity, which are most commonly buried within the broader category of the terrestrial or marine environment. Where there are specific policies for managing freshwater systems, the focus is primarily on the management of water resources for people, with little consideration to ensure that ecological functions are maintained, and that freshwater species are conserved . Even major regional and legally binding policy initiatives such as the European Water Framework Directive that uses the biological structure of water bodies to assess quality targets does not include the conservation of ecosystems per se within its implementation cycles (Voulvoulis, Arpon, & Giakoumis, 2017) .
| Policy
The Alliance will address the freshwater biodiversity and conservation policy gap through its work to build awareness of the impor- the Alliance aims to facilitate science-policy meetings at the national, regional, and global scales, bringing together scientists, policy makers, conservationists, funding bodies, and campaigners. Where existing policies already exist, such as the SDGs or the water-related Nationally Determined Contributions (NDCs) that are part of the post-2020 climate actions for countries, the Alliance will help to make available the relevant scientific knowledge and highlight the importance of functioning freshwater ecosystems for fulfilling other related SDGs, such as for poverty alleviation.
| NEXT STEPS
In 2018, the Stockholm World Water Week (www.worldwaterweek. org) addresses the theme of 'Water, ecosystems and human development' . This international event represents a unique opportunity to highlight the conservation of freshwater species and ecosystems as a core component of sustainable water resource management and international freshwater policy (Moulton, 2017) . World Water
| NEXT STEPS
Week provides a platform on which the Alliance will be presented to the private and policy sectors that are often otherwise difficult for the science and conservation community to reach.
| NEXT STEPS
The core areas of work for the Alliance, if addressed independently, will provide important information and facilitate progress, but for effective impact at the scale required to address this global crisis, all must be brought together in synergy through a single global initiative. This needs to be on a similar scale to that accomplished through the Census of Marine Life (www.coml.org), but with a clear pathway for influencing and informing policy that will in turn lead to conservation action and more sustainable development. In this context the objective of the Alliance is to unite the expertise of a diverse range of organizations, creating a coherent approach leading to effective action. Examples of priority goals for the Alliance within these five core areas of work are presented in Table 1 . Aquatic Biodiversity (NRF-SAIAB). We invite like-minded individuals, organizations, and governments to join the Alliance and to contribute their expertise, energy, and inspiration. In this way we aim to build a truly global representation within the Alliance.

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