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World Fish Migration Day 2020

October 23, 2020
The World Fish Migration Day 2020 takes place on October 24th with online events around the world. Image: WFMF

Communities around the world will join together tomorrow to celebrate World Fish Migration Day. The event – started in 2014 – aims to raise awareness of the importance of migratory fish populations, and the threats they face. This year World Fish Migration Day will feature over 300 events across 66 countries – many of which are available to join online.

This year’s event – the fourth of its kind – takes place in the wake of the latest Living Planet Index for Migratory Freshwater Fish report, which found an average 76% global decline in monitored migratory fish populations since 1970. The picture is particularly bad in Europe, where declines of 93% were observed. These declines are attributed to a combination of habitat loss, dam and hydropower construction, climate change and over-exploitation of populations.

Despite these startling trends, the World Fish Migration Foundation say that migratory fish do not receive the public attention they deserve. The aim of their Day is to raise public awareness of the importance of migratory fish populations in our lives, and to encourage citizen action in asking NGOs and policy makers to conserve and restore ‘global swimways’.

The ‘Love Flows’ documentary profiles some of the events from 2018 World Fish Migration Day, showcasing local celebrations, community knowledge, and shared visions for global rivers.

This year’s World Fish Migration Day is centred around a series of online webinars starting this evening (European time, 23rd October), which will discuss events and issues from around the world. You can explore hundreds of other global events through an interactive map here.

The Day will culminate with the Eurofishion song contest, where ten finalists will perform their migratory fish-themed songs for judges. The shortlisted videos include children singing about salmon at a Slovakian zoo, a coordinated dance party about urban trout populations in Finland, a South African children’s choir singing a new piece written by an 11-year old choir member, and a Kenyan hip-hop track about water pollution in rivers.


Explore the World Fish Migration Day events here.

Safeguarding freshwater life beyond 2020: 14 recommendations for environmental policy

October 15, 2020
A headwater stream in the Austrian Alps. Image: Theo Crazzolara | Flickr Creative Commons

Freshwater biodiversity is in a critical state of decline across the world, as startlingly shown in the most recent WWF Living Planet report. This year, updates to two international policy frameworks which could have significant influence on the future of freshwater life – the Convention on Biological Diversity (CBD) and the European Union (EU) Biodiversity Strategy – are being prepared. How can we ensure that global freshwater biodiversity is properly valued and protected by these frameworks over coming decades?

An international research team led by Dr. Sonja Jähnig at the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) in Germany have published a journal paper containing 14 key recommendations for the global protection of freshwater biodiversity. Their aim is to encourage decision makers to ensure that both the post-2020 CBD Global Biodiversity Framework and the post-2020 EU Biodiversity Strategy better account for freshwater ecosystems.

“This is an important moment to bring scientific knowledge into the process,” says Dr. Jähnig. “Political strategies and decisions must emphasise the unique ecology of freshwater life and the many threats to it. In previous regulations, the protection of freshwaters has often been treated in an inferior manner. Inland waters have been included within land regulations – because they are not marine – or with seas and oceans – because they are aquatic. It is time that freshwater biodiversity is recognised in its own right – the latest Living Planet Report shows that the loss of freshwater populations is the most dramatic – a loss of 84 percent between 1970 and 2016,” Dr. Jähnig states.

The new open-access paper – published in Conservation Letters – draws on the expertise and experience of its 21 authors, many of whom have been involved in major freshwater research projects such as MARS and BioFresh in recent years. Their collaboration was initiated at the ALTER-Net / Eklipse conference in Ghent in July 2019, which was hosted to discuss EU biodiversity strategy post-2020.

As co-author Dr. Astrid Schmidt-Kloiber explains, this is a crucial time for environmental policy and conservation, “The year 2020 marks the end of the UN biodiversity decade. In the last 10 years major efforts have been undertaken to save the world’s biodiversity, but none of the Aichi Targets has been met so far. Now the Convention on Biological Diversity and the EU Biodiversity Strategy need to be prepared and adapted for the next 10 years and we wanted to make a contribution that exclusively deals with the biodiversity of freshwaters, which are among the most threatened ecosystems on earth.”

The authors’ 14 recommendations are split into four categories which encompass visioning, planning, monitoring and practice for freshwater conservation.

The 14 recommendations for freshwaters in the post-2020 Global Biodiversity Framework. Image: van Rees et al (2020)

Visions and targets for freshwater conservation

The article’s first recommendation is also its most radical and urgent: that freshwaters should be considered a true ecological ‘third realm’ that deserves legal and scientific prominence in biodiversity frameworks and strategies. Freshwaters can sometimes ‘slip between the gaps’ of terrestrial and marine policies, which means that their unique threats, valuable ecosystem services and distinctive ecology are not properly accounted for and protected.

Lead author Dr. Charles van Rees explains, “We want to communicate the uniqueness of freshwater ecosystems and biodiversity, how they cannot be managed similarly to terrestrial or marine systems, how they are intertwined with human health and societal water security, and how they are more intensely threatened than other realms of biodiversity.” 

As Dr. van Rees notes, the authors recommend that freshwater ecosystems should be recognised and framed as life-supporting systems that provide vital functions to humans and non-humans alike. The processes that shape freshwater systems – and the services they provide – often take place across wide geographical scales and long timescales, and ensuring that these systems retain connectivity through policy and management is another of the authors’ recommendations. This has implications for how different environmental policies are implemented, as co-author Dr. Gregor Kalinkat outlines, “Better integration of water-related regulations like the Water Framework Directive and the EU Biodiversity Strategy is a key goal that needs to be achieved.”

A history of global environmental policies which influence freshwater conservation. Image: van Rees et al (2020)

Creating the conditions for effective freshwater conservation

Linked to their previous recommendation, the authors state that freshwater ecosystems should be managed across their whole catchment, regardless of political boundaries. Freshwaters don’t function in isolation from land, air and sea, but instead are in a constant state of environmental exchange and dynamism, which can lead to complex sets of human pressures. Managing freshwaters at ‘the catchment scale’ is widely agreed to be the most effective way to address these dynamics. This links to another of the author’s recommendations: to incorporate insights from cutting-edge ecological systems theory around complexity, non-linearity and feedback loops.

The authors highlight that whilst the designation of new protected areas can be politically and economically challenging, initiatives such as wetland restoration have the potential to provide simultaneous climate and conservation benefits. They also discuss how large and ‘charismatic’ freshwater species have the potential to act as valuable ‘flagships’ in raising public awareness of conservation initiatives. The environmental impacts of invasive freshwater species continues to grow as an issue, and the authors recommend that regulatory frameworks should better account for their monitoring, assessment and management.

Monitoring and planning for the future

In planning for how freshwaters are best studied in support of environmental policy, the authors make three recommendations around biodiversity monitoring and data. First, they state that freshwater monitoring programmes should be better coordinated and funded at national and global scales. Second, they advocate for making large freshwater datasets open-access and widely available – as is already happening through the Freshwater Information Platform – as a means of supporting collaborative research across large geographical areas.

Third, they suggest that future biodiversity monitoring schemes should take advantage of novel research methods and data sources in order to better account for underrepresented – but ecologically crucial – groups like parasites, fungi, and bacteria. They highlight an emerging toolkit of monitoring methods, including environmental DNA, remotely sensed earth observations, culturomics and citizen science as valuable avenues for research.

Dr Astrid Schmidt-Kloiber says, “I think that we need Europe-wide specific harmonised freshwater monitoring programmes to create a reliable baseline about the current state of freshwater biodiversity and to help the Red Listing process. Though the Water Framework Directive has already created a lot of valuable data, it has to be emphasised that WFD monitoring captures only a subset of the freshwater biota, as it is not specifically meant to record, for example, the total species diversity. This is directly related to better access to existing and mobilisation of new biodiversity data, which also still would need major improvements.”

In using this data to shape conservation practice, the authors recommend that future freshwater policies should encourage catchment management which balances both human and wildlife water needs. Freshwater ecosystems are often subject to numerous competing demands on the resources they provide, and the authors highlight the range of new decision-support tools which can help policy makers navigate their complexity.

Synergies between the 14 recommendations and the 6 ‘bending the curve of freshwater decline’ priority actions outlined by David Tickner and colleagues (2020). Filled circles indicate parallel coverage; open circles denote where recommendations provide a means of implementation for priority actions. Image: van Rees et al (2020)

Cross-cutting issues for freshwater conservation

The final two recommendations in the paper relate to cross-cutting issues for freshwater management. First, the authors state that freshwater biodiversity species extinction risk listing and protections should be better informed by global assessments. They highlight how a relatively small proportion of freshwater species classified as threatened by the IUCN Red List are adequately protected by EU biodiversity policies.

Second, they suggest that future environmental policies should support the use of Integrated Water Resources Management as a means of sustainably managing freshwater systems, particularly across administrative and political boundaries. They describe how key contemporary issues surrounding multiple stressors and environmental flows are being managed through IWRM approaches.

Summing up and looking forward

The paper provides a succinct and powerful statement in support of better freshwater conservation and management, and is informed by cutting-edge research and theory in the field. “We hope that this paper will highlight under-recognised research on freshwater ecology and conservation and bring the freshwater biodiversity crisis to the forefront,” says Dr. Charles van Rees. “More than raising the alarm, though, we hope to provide more actionable, practicable guidelines and suggestions for how governments can support the research and management needed to address this crisis. This is a major step toward what David Tickner and colleagues recently called ‘bending the curve’ for freshwater biodiversity,” Dr. van Rees explains. 

“Through the joint effects of climate change, overexploitation, pollution, species introduction, and many other factors, we are losing biodiversity at an alarming rate, and at a global scale,” adds co-author Dr. Stephen Thackeray. “These losses are especially pronounced in freshwater habitats, and yet the plight of freshwater species specifically does not always get the public and policy attention that it deserves. It is clear that we need to take action to protect our freshwater wildlife, and it is our hope that our recommendations can help guide decision making and conservation for these imperilled ecosystems,” Dr. Thackeray suggests.

“Even if results of international conservation efforts have been very sobering so far – we scientists will continue to contribute our expertise to highlight the dramatic loss of freshwater biodiversity and help to mitigate and stop it. The recommendations formulated can help to improve the political framework for the protection of aquatic biodiversity,” Dr. Sonja Jähnig concludes.


van Rees, CB, Waylen, KA, Schmidt‐Kloiber, A, et al. Safeguarding freshwater life beyond 2020: Recommendations for the new global biodiversity framework from the European experience. Conservation Letters. 2020; e12771.

‘Lost’ Brazilian frogs rediscovered with environmental DNA

October 9, 2020
Phasmahyla guttata – the spotted leaf frog – which had not been documented in the Parque Nacional da Serra dos Órgãos, Brazil since 1977 and was ‘rediscovered’ using eDNA in the new study. Image: Leo Malagoli | Cornell University Press Office

Scientists have used cutting-edge DNA techniques to identify the presence of a Brazilian frog species not seen since 1968, and thought to be extinct.

Organisms leave DNA traces in soil, water and air in their habitats, and this ‘environmental DNA’ (or eDNA) can increasingly be sampled and matched to reference databases. So, even if researchers don’t see or hear a particular species, they can identify the eDNA ‘footprint’ it leaves behind in an environment.

The ‘lost’ frog, Megaelosia bocainensis, was one of seven frog species – including four other declining species, and two that had disappeared locally – that were detected by the new study, published in Molecular Ecology.

The research team collected and analysed frog eDNA from stream and pond water at five sites in the biodiverse Atlantic Coastal Forest and Cerrado grasslands in southeastern Brazil. They were looking for 13 frog species that are presumed extinct; 12 species that have disappeared locally; and five species that were once abundant but are now scarce.

“Little bits of DNA in the environment don’t tell us about how many individuals there are or whether those individuals are healthy, but it does tell us that the species is still present,” said senior author Kelly Zamudio, the Goldwin Smith Professor of Ecology and Evolutionary Biology in the College of Arts and Sciences at Cornell University.

“This is one more kind of survey data, and for species that are declining or locally disappeared, it not only means they are there, but there’s now the potential to study them in more detail,” Zamudio added.

A museum specimen of Megaelosia bocainensis, collected in 1968. The species disappeared from Parque Nacional da Serra da Bocaina, Brazil, and was detected by eDNA surveys. Image: Délio Baêta | Cornell University Press Office

The researchers then extracted the eDNA from their water samples and genetically sequenced it. This allowed them to isolate frog eDNA from that of humans, pigs, chickens and other organisms which share the environment.

“Now you’ve got a subset of genetic sequences that we know only belong to frogs, and then it’s step by step, going finer and finer, until you get to the genus and species you are looking for,” Zamudio said.

Because Megaelosia bocainensis has not been seen for over 50 years, the research team didn’t have tissue samples to extract DNA from for comparison with their eDNA samples. However, they did have the genetic sequences for the frog’s sister species in the genus Megaelosia.

“We know there’s a Megaelosia there,” Zamudio said, “we just don’t know which one it is, but the only one that has ever been reported there historically is the one that went missing. Do we believe it? That’s how far the analysis can take us.”

Using eDNA techniques allows scientists to search for traces of such elusive species at low population densities. It offers rich potential in characterising species geographic ranges, population fluctuations and conservation status. It is already being used to track the spread of invasive species through freshwater ecosystems, such as Asian carp in the USA.

The discovery of the Megaelosia eDNA in the water samples clearly signals the need for more targeted amphibian research and conservation efforts in the region. How many more ‘lost’ freshwater species are still out there, quietly persisting in tiny numbers, despite multiple human pressures and threats? Could eDNA techniques help conservationists better identify and protect these species in the future?


Lopes, CM, Baêta, D, Valentini, A, et al. Lost and found: Frogs in a biodiversity hotspot rediscovered with environmental DNA. Mol Ecol. 2020; 00: 1– 10.

84% of global freshwater species populations lost since 1970: can we ‘bend the curve’ of this trend?

September 25, 2020
The Yangtze River in China – home of the Chinese sturgeon, populations of which have declined by 97% since 1982 due to habitat degradation. Image: Boris Kasamov | Flickr Creative Commons

Global populations of mammals, birds, amphibians, reptiles and fish have, on average, declined by two-thirds since 1970, according to the latest WWF Living Planet Report, released earlier this month. Continuing the trends shown in past reports, freshwaters are particularly imperilled: with 84% of global freshwater species populations lost between 1970 and 2016.

The bi-annual Living Planet Report tracks trends in global wildlife abundance, based on data from 21,000 populations of more than 4,000 vertebrate species. Population declines in freshwater ecosystems – which equate to an average annual loss of 4% globally – were higher than those in terrestrial and oceanic environments.

Significant declines in global freshwater species populations

WWF have published a Deep Dive into Freshwater’ document looking at the stark findings of the Living Planet Report, and outlining ways to support global freshwater conservation in their wake. The publication states that population declines are particularly acute among freshwater amphibians, reptiles and fishes. Whilst freshwater population declines have been observed globally, they are most severe in Latin America and the Caribbean.

The drivers of these declines include habitat degradation, pollution, over-exploitation, invasive species and sand mining. These pressures are not always adequately managed in a large-scale, cross-boundary way by conservation schemes. The report suggests that large ‘megafauna’ species are particularly threatened, as their populations are less resilient to environmental pressures. One stark example is the spawning population of the Chinese sturgeon in China’s Yangtze river, which declined by 97% between 1982 and 2015 due to dam construction.

Global freshwater species populations declined by 84% on average between 1970–2016. Image: WWF Living Planet Report 2020
Global wetlands are being lost at a rate of around 1.6% each year – three times faster than rainforests. Image: WWF Living Planet Report 2020

Lost wetlands and fragmented rivers

The ‘Deep Dive’ publication identifies two key trends in freshwater ecosystem change which are likely to be contributing to freshwater population declines. First, it states that nearly 70% of global wetlands have been lost since 1900, and they are still being destroyed at a rate (around 1.6% per year) three-times faster than rainforests. Wetlands are crucial ecosystems for many endangered and endemic species, and provide many benefits such as natural flood prevention to human communities. However, they are being widely drained, dammed and dyked across the world, often to support crop and livestock production.

Second, a 2019 mapping of millions of kilometres of global rivers revealed that only one-third of the world’s 242 longest rivers (more than 1000km in length) remain free-flowing. The majority of the remaining free-flowing rivers are found in remote areas of the Arctic, Congo and Amazon basins. The construction of dam and hydropower infrastructure can significantly alter the flows of water, sediment and nutrients through a river catchment, and inhibit the movement of migratory species. Despite increasing global attention to the issue, proposals for new dam constructions continue apace on many large river systems across the world.

Bending the curve of freshwater biodiversity loss?

In a blog posted earlier this week, Dean Muruven, WWF Global Freshwater Policy Lead, urges everyone working in freshwater conservation to pause and reflect on the results of the Living Planet Report. He writes, “If you have been an academic championing freshwater conservation throughout your career, you may have to finally accept that all those important (and they are critically important) science papers and commentary pieces in top academic journals have not had the expected impact. Instead of helping to save species, they have largely catalogued their decline. Maybe it’s time to start focusing on policies as well as papers — and perhaps even protests.”

Muruven argues that it is time for freshwater conservationists to radically improve how they communicate their work to wider audiences. He suggests that this involves “stepping out of the freshwater conservation bubble and having those difficult conversations with those that share a different a world view from us — to pave the way for learning and partnerships.”

The six priorities in the WWF Emergency Recovery Plan for Freshwater Biodiversity. Image: WWF

The WWF’s current approach to fostering widespread dialogue and action on tackling the freshwater biodiversity crisis centres on their Emergency Recovery Plan for Freshwater Biodiversity. The plan, discussed in a blog back in February, is based on six key themes.

They are: letting rivers flow more naturally; reducing pollution; protecting critical wetland habitats; ending overfishing and unsustainable sand mining in rivers and lakes; controlling invasive species; and safeguarding and restoring river connectivity through better planning of dams and hydropower.

The authors of the Emergency Recovery Plan suggest that unless significant collective action is taken to ‘bend the curve’ of freshwater biodiversity loss globally then the downward trends of species loss and ecosystem degradation will continue apace. The time to tackle this crucial issue is now: the key question, as Muruven puts it, is, “are we capable as a freshwater community of coalescing around the Emergency Recovery Plan for the next five years and collectively have a go at bending the curve?”


Read the WWF Living Planet Report 2020

Chemical pollution limits the ecological status of European freshwaters

September 11, 2020
Grand Canal Dock in Dublin: the legacy of heavy industry poses chemical pollution issues in many urban waters in Europe. Image: William Murphy | Flickr Creative Commons

Chemical pollution poses a significant threat to the health of freshwater ecosystems, both in Europe and across the world. A major 2014 study suggested that chemical pollution has acute, potentially lethal, impacts on freshwater organisms at more than one in ten monitored sites across Europe; and long-term negative impacts at almost half of these sites.

The challenge is an unenviable one for water managers: how to monitor and manage more than 140,000 different toxic substances, each with unique properties and impacts? And in addition, how to understand and mitigate the interactions and impacts of chemical ‘cocktail’ mixtures on the aquatic environment?

Disciplinary differences in monitoring chemical pollution

At present, aquatic chemical pollution is monitored in two main ways. Applied ecologists generally carry out field observations in a process of ‘gradual assessment’, which allows them to assess ecological impacts on a five-point scale ranging from major to minor. On the other hand, ecotoxicologists base their assessments on laboratory experiments, and provide a binary diagnosis of water quality: either a toxic chemical (or mixture) is present at an acceptable level; or it is too high, and should be managed.

These two approaches present a dilemma for water managers: how to combine and act on the different diagnoses they receive? A new study published this week outlines how applied ecologists and ecotoxicologists can better synthesise their results to provide practical information for water managers seeking to mitigate the effects of chemical pollution.

Synthesising applied ecology and ecotoxicology approaches

The study, a collaboration by an interdisciplinary group of European researchers, proposes five ecotoxicological classes that can be linked to the five degrees of ecological impacts. Lead author Leo Posthuma from the Dutch National Institute for Public Health and the Environment explains,

“In this study, we bridged disciplinary differences by building an integrative data set for European surface waters, and analysing whether and in how far chemical pollution (from the applied ecotoxicologists) acts as a limiting factor to ecological status (from the applied ecologists). We found that mixtures matter: increased exposure to mixtures of 24 priority substances of Europe-wide concern implies increased limitations to maintain or reach good ecological status.”

“Applied ecologists and applied ecotoxicologists usually give separate information to water quality managers,” Posthuma outlines. “This is because applied ecology is built on field observations, whereas applied ecotoxicology is based on laboratory toxicity tests, as making chemical exposure gradients for over 350,000 substances in trade across the globe would be impracticable and unethical. Water quality managers are thus often confronted with two independent types of management advice: views from ecologists, and views from ecotoxicologists. That is not an optimal situation, especially since the ‘indicator systems’ of each discipline are vastly dissimilar,” he says.

The relationship between ecological status and mixtures of chemical pollutants. Image: Posthuma et al (2020)

Providing comprehensive and practial advice to water managers

Writing in Nature: Scientific Reports, the research team, drawn from RIVM, WEnR, Deltares and other European partners, outline how current water quality assessments might show the presence of a chemical pollution problem, but don’t diagnose its magnitude. They outline ways of evaluating the dynamics, geographies and impacts of chemical mixtures in the aquatic environment to help identify ‘hot spots’ of chemical pollution requiring management.

Crucially, they describe the relationships between chemical pollution and the ecological status of water bodies. This provides important information for water management, as Posthuma explains, “Our collaboration is important because – if successful – we can for the first time provide water quality protection, assessment and management experts with unified and comprehensive types of management information.

“Our findings are important in two ways,” Posthuma continues. “First, the outcomes show that chemical mixture exposures should not be neglected as key cause of reduced ecological status. That is: forgetting mixtures in diagnosing reduced water quality may result in ‘ill-defined measures’ which will not succeed, as chemical pollution is the hidden weakest link, limiting recovery.

“Second, the outcomes show that it is feasible to bridge the classical gap between applied ecology and ecotoxicology in such a way that the assessment of chemical pollution is now aligned with the ‘thinking’ of applied ecologists,” Posthuma says. “The approach we describe has the potential to be used worldwide.”


Posthuma, L., Zijp, M.C., De Zwart, D. et al. Chemical pollution imposes limitations to the ecological status of European surface waters. Sci Rep 10, 14825 (2020). (open access)

World Water Week at Home

August 26, 2020
World Water Week at Home 2020 explores water management, climate change and development. Image: World Water Week

Water and development experts from around the world are coming together online this week to discuss the key issues and big ideas in global water management. Now in its 29th year, World Water Week is taking place ‘At Home’ this year between 24–28 August, with 120 online sessions open for free to the public. Sessions are both available live and archived on YouTube.

At the opening event on Monday, Stockholm International Water Institute Executive Director Torgny Holmgren emphasised the importance of water-related climate change mitigation across many of the sessions. “At the climate conference COP25 in Madrid last year we started to see a welcome breakthrough where more countries began to search for water solutions, not least in their nationally determined contributions to the Paris agreement. Now we hope that this thinking will gain more traction ahead of COP26 next year,” Holmgren said.

Another major trend across the sessions is how national governments can promote environmental resilience in their economic and social rebuilding after the Covid-19 pandemic. “Water is a necessity of life and an engine for development. Through its response to the Covid-19 pandemic, the world has proved that it has the capacity to change rapidly,” said Isabella Lövin, the Swedish Minister for Environment and Climate. “We should use this momentum to transform our way of living into what is in line with reaching the sustainable development goals. Sustainable water management is an integral part of that,” she argued.

This week’s sessions involve a range of organisers and speakers from global NGOs, academia, business and government. “We are very happy that to be able to offer such a diversity, with distinguished speakers helping us understand important new trends,” said Gabriela Suhoschi, Director of World Water Week. “In today’s turbulent world there is great need for this type of reflection and analysis, so I hope that many people will seize the opportunity to tap into this knowledge,” she added.

There are a number of sessions which are likely to be of particular interest to our readers. Tomorrow (Thursday 27th August) practitioners will present results and lessons from a 7-year project on the conservation and restoration of floodplain areas across the Danube river basin, involving The Coca-Cola Company and Foundation, the International Commission for the Protection of the Danube River and WWF-CEE. Later in the day, another session will showcase new technological approaches to detect and monitor Harmful Algal Blooms, whilst a third will explore the links between Nature-based solutions for water security and climate finance.

On Friday, a series of sessions affiliated with the Every Drop Counts initiative explore themes around water management and gender, including strengthening the role of female voices in decision making. Later on, the Alliance for Water Stewardship will run a session on the challenges of implementing water stewardship in agriculture, before the week is concluded in a closing ceremony.

A number of the sessions which have already taken place have been uploaded to the World Water Week At Home YouTube channel, with more forthcoming. We particularly enjoyed this session hosted by the Rede Brasil do Pacto Global on the potential of Nature-based solutions to address water scarcity caused by ongoing climate change.

You can follow the remainder of the event online through the project website and social media, using the #WWWeek hashtag.

Indigenous Knowledge offers valuable insights into Arctic freshwater ecology

August 15, 2020
Ice on the Sylvia Grinnell River in Nunavut territory in Northern Canada. Image: Fiona Paton | Flickr Creative Commons

Freshwater biodiversity in the Arctic is not fully documented or understood by scientists, particularly in remote and inaccessible areas. However, ongoing climate change is altering Arctic freshwater ecosystems – increasing water temperatures and ice melt rates, altering flow regimes and affecting animal migration routes. At the same time, increasing rates of human development and resource extraction – including mining and hydropower development – threaten water quality and habitat availability across many Arctic freshwaters.

The authors of a new study published in Freshwater Biology suggest that learning from Arctic Indigenous Peoples is critical in informing a better shared understanding of both the historical and current state of Arctic freshwater biodiversity in response to these pressures.

Lead author of the study, Dr. Jennie A. Knopp from Oceans North says, “In working with the Conservation of Arctic Flora and Fauna Freshwater Experts Network on determining the current state of freshwater biodiversity in the circumpolar Arctic based on existing data, we wanted to highlight the wealth of information contained within circumpolar Indigenous Knowledge bases. We wanted to bring awareness to and share existing documented Indigenous Knowledge on Arctic freshwater ecology. In turn, the Indigenous Knowledge revealed new species records not contained in any of the western scientific databases.”

Their study is the result of a systematic literature review summarising previously documented Indigenous Knowledge observations on Arctic freshwater biodiversity from Canada, Greenland, Norway, Sweden, Finland, Russia, and the U.S.A. (Alaska). Documents surveyed included peer-reviewed journals, reports, books, videos, theses and conference proceedings.

Dog sled in Nunavut territory in Northern Canada. Image: Fiona Paton | Flickr Creative Commons

Their research highlights five key points. First, although Indigenous Knowledge of freshwater biodiversity has been passed on through oral traditions for millennia, it is only in recent years that this has been documented, both by Indigenous Peoples and scholars. The researchers collated 285 documents containing Indigenous Knowledge on Arctic freshwater biodiversity, largely related to populations of fish species and changes in freshwater habitat. This process revealed a wealth of Indigenous Knowledge on Arctic freshwater biodiversity. However, the researchers acknowledge that there is still significant Indigenous Knowledge on freshwaters which has yet to be documented or compiled, particularly in local and Indigenous languages.

Second, the Indigenous Knowledge consulted in this study improved Western scientific knowledge of freshwater fish species distributions. Seventeen species of fish, including the Asiatic trout, crucian carp and the critically-endangered European sea sturgeon, were recorded by Arctic Indigenous communities, but not found in fish monitoring data compiled by the Circumpolar Biodiversity Monitoring Program (CBMP). Indigenous Knowledge revealed information on both species disappearances and new species records over time, a difficult metric to document in large-scale scientific surveys, and one that is crucial for the early detection of invasive species and other climate change impacts on Arctic ecosystems.

Third, the Indigenous Knowledge compiled by the researchers showed significant trends in decreasing water levels in rivers and lakes, shorter periods of ice cover, decreasing ice thickness and increasing permafrost thaw across circumpolar regions. The researchers argue that such observations by communities who rely on Arctic freshwater systems are crucial in identifying key locations for conservation and management actions where possible.

Fourth, the researchers found that Indigenous Knowledge contributes wider spatial and temporal coverage of Arctic freshwater ecosystems than that surveyed by Western science. In particular, they found information on freshwater biodiversity from remote regions of circumpolar Alaska and Russia that are not well-documented in scientific studies. In addition, these records can provide longer-term indications of biodiversity trends than many Arctic scientific studies.

Fifth, the researchers emphasise that whilst their review identifies important ways in which Indigenous Knowledge can complement Western science to understand emerging themes in Arctic freshwater biodiversity, there remain a number of challenges for the future. One key point is that the data in the documents reviewed in this study are unlikely to capture the depth and breadth of Indigenous Knowledge on freshwater ecosystems held by knowledge holders. Similarly, there are significant ethical and methodological issues over how Indigenous Knowledge and Western science frameworks of knowing and ordering the world can be brought together in a respectful and productive manner.

Overall, the paper offers a valuable insight into the wealth of information Indigenous Knowledges can contribute to the study of Arctic freshwater biodiversity. “We hope this research will encourage limnologists to collaborate with Indigenous groups in their study areas in an attempt to start to understand the wealth of information on freshwater ecology and biodiversity held in the mind of the Indigenous Knowledge holders and to work in partnership with Indigenous experts,” Dr. Knopp concludes.


Knopp, JA, Levenstein, B, Watson, A, Ivanova, I, Lento, J. (2020), Systematic review of documented Indigenous Knowledge of freshwater biodiversity in the circumpolar Arctic. Freshwater Biology. 00: 1– 16.

Half of known freshwater megafauna species threatened with extinction

July 31, 2020
The Beluga, or European sturgeon. Image: Charlene N Simmons | Flickr Creative Commons

Many of the largest and most iconic freshwater species in the world are threatened with extinction. There are around 200 species of such ‘freshwater megafauna’ – species weighing more than 30kg, and found on every continent except Antarctica – of which 34 species are listed as Critically Endangered by the IUCN Red List, and half are classified as Threatened.

Freshwater megafauna such as the beluga sturgeon, American alligator, Yangtze finless porpoise, and Caspian seal often have complex life cycles and extensive habitat requirements. As such they are sensitive to habitat loss, over-harvesting and river fragmentation. A recent study found that freshwater megafauna declined by 88% globally between 1970 and 2012, with a 94% decline in megafauna fish species.

Some freshwater megafauna – such as the arapaima – are well-known ‘flagships’ of particular ecosystems and cultures, and recent work has assessed the potential for their conservation to prompt ‘umbrella’ ecological benefits to the health of the wider ecosystem. However, at present, freshwater megafauna species are significantly threatened across the world, and a paucity of available data means their ecological status might be worse than current assessments suggest. IUCN Red List Assessments are currently incomplete for 49 – or 24% – of freshwater megafauna species.

Two Baikal seals basking on the banks of Lake Baikal. Image: Sergey Gabdurakhmanov | Flickr Creative Commons

A new study seeks to identify the factors that make freshwater megafauna more vulnerable to extinction. Dr. Fengzhi He from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries and colleagues collated eight ‘life-history’ traits such as size, lifespan, habitat type and feeding habits for 206 freshwater megafauna species. They then used computer models to examine the relationships between extinction risk and the combined effects of these traits, as well as the influence of human impacts.

“We found that traits related to species’ recovery potential including lifespan, age at maturity, and fecundity, as well as human impact, are important factors influencing the extinction risk of freshwater megafauna,” explains He, the lead author of the new study, accepted in the Conservation Biology journal. 

“Accounting for both IUCN Red List assessments and our model predictions, 50% of all freshwater megafauna species are considered as threatened. In addition to existing hotspots including the Ganges-Brahmaputra and Mekong basins and the Caspian Sea region based on the IUCN Red List, Amazon and Yangtze basins emerged as global diversity hotspots of threatened freshwater megafauna when we consider both the IUCN Red List assessments and our model predictions,” He continues.

A fleeting sighting of an Amazon river dolphin. Image: Michiel van Nimwegen | Flickr Creative Commons

The researchers also applied their models to predict the extinction risk of the 49 megafauna species listed by the IUCN as ‘Data Deficient’ or ‘Not Evaluated’. He explains, “Our results showed that species that are not evaluated yet or have insufficient data for assessment could also be threatened. We might miss the window-of-opportunity to protect these species from extinction if conservation actions are delayed.”

In common with most contemporary freshwater research, the study emphasises the need for better ecological data to help guide conservation and restoration efforts. “Our study highlights the importance and necessity of comprehensive and updated assessments for global freshwater megafauna species, as well as for overall freshwater species,” He says. “More studies are required to improve our knowledge of their life history and critical habitats, such as reproduction and nursery grounds. It is essential to sustain the reproduction and recovery potential of freshwater megafauna. For example, maintaining the connectivity of rivers is important for the reproduction of many migratory megafauna species.”


He, F. et al (2020), “Combined effects of life‐history traits and human impact on extinction risk of freshwater megafauna”, Conservation Biology,

European rivers fragmented by over one million barriers – and 10% of them are obsolete

July 17, 2020
Caban Coch dam on the Elan River in Wales. Image: Sara Barrento

It is estimated that there are over one million barriers fragmenting European rivers, of which over 100,000 are obsolete, according to new research. The findings were published by Adaptive Management of Barriers in European Rivers (AMBER), an EU Horizon 2020 project, in their AMBER Barrier Atlas.

The Atlas collates information on 630,000 river barriers across Europe, from large dams to small weirs, fords and culverts, and is based on existing datasets. However, AMBER researchers estimate that at least one third of the continent’s river barriers are unrecorded, which means the real figure could be well over 1 million.

Their estimates are based on project researchers walking 2,700km of rivers and streams in 28 European countries to record the barriers along their courses. This fieldwork also suggests that around 10% – or an estimated 100,000 – of European river barriers are obsolete. In other words, such barriers continue to impede the ecological health and functioning of European rivers, without serving their original purpose.

The Radovna River in Slovenia – a mountain stream impacted by hydropower barriers. Image: Johann/UNSPLASH

“Even areas that were considered to be relatively pristine and well connected are in fact impacted by barriers,” says Carlos Garcia de Leaniz, AMBER project coordinator and Professor of Aquatic Biosciences at Swansea University. “For example, in the Balkans, our field validation indicates that 80% of barriers do not appear in current inventories, making the fragmentation of these rivers much worse than people thought.”

The creation of the Barrier Atlas was the first step in the ongoing AMBER project, in response to the inconsistent and incomplete existing datasets on river barriers across Europe. The interactive Atlas allows users to explore, visualise and download data on the different kinds of river barriers across the continent.

The project has defined common standards for individuals and institutions to report river barriers in their own countries. The free Barrier Tracker app is central to the project’s citizen science programme, allowing anyone to quickly document and upload information on river barriers to the AMBER database.

The AMBER Barrier Atlas, showing different kinds of river barriers across Europe.

The project’s mapping of European river fragmentation is intended to provide the basis for river managers to plan effective and and efficient restoration schemes. One early project finding is that losses in river connectivity – whether of water flows, sediment, migratory fish movements, or a combination of these – is typically caused by a relatively small percentage of barriers. As a result, it makes sense to focus management efforts on such barriers. AMBER is currently developing a suite of tools to allow river managers to plan their work accordingly.

“Over 60% of EU freshwater systems are in a poor state in part due to habitat fragmentation, says Barbara Belletti who led the development of the AMBER Atlas at Politecnico di Milano with Wouter van de Bund at the Joint Research Centre of the European Commission. “To improve the health of our rivers, we need to reconnect them—our Atlas and tools will support this endeavour.”


AMBER project website

Read peer-reviewed publications from the AMBER project

Read Let it Flow, the AMBER project magazine

Pond creation boosts biodiversity and rare species in agricultural landscapes

July 3, 2020
Ponds created in farmland in the Midlands of England boosted biodiversity and rare species. Image: Freshwater Habitats Trust

Creating pond habitats in farmland can significantly improve landscape biodiversity over relatively short time periods, according to a recently-published study.

Ponds are the most common freshwater habitat – there are an estimated 3 billion worldwide – and often support rich and rare biodiversity. However, they are often overlooked in both environmental policy and management: for example, there is no provision in the European Water Framework Directive to monitor and manage the continent’s 10 million ponds.

Important – but declining – freshwater biodiversity habitats

A 2019 survey by the Freshwater Habitats Trust found declines in freshwater biodiversity in British ponds in protected areas in recent decades. This is significant because these ponds supported more species, and more rare species, than the most biodiverse UK river habitats. Interestingly, the FHT survey suggested that low-level stock grazing around ponds helps suppress the growth of shading scrub woodland on their banks, and so help maintain their biodiversity.

As a result, we can understand pond habitats as an important part of ‘semi-natural’ landscapes where human and non-human natures interact. Accordingly, could creating new ponds in British farmland help increase both the biodiversity and the number of rare species that these landscapes support?

This is a key question underpinning the new study, funded by the Environment Agency, and recently published in the journal Biological Conservation. Its authors studied the ecological impacts of the creation of ‘clean water’ ponds in farmland in the Midlands of England over a nine-year period. Clean water ponds are habitats which are not connected to streams or ditches, and are filled with unpolluted surface- and ground-water.

Digging out a new pond in farmland. Image: Freshwater Habitats Trust

Pond creation significantly increases biodiversity in agricultural landscapes

The project team found that creating twenty such ponds across a 10km² area of farmland increased the number of wetland plant species by more than a quarter (26%), and almost trebled the number of regionally rare plants (a 181% increase) over a five year period. The results suggest that pond creation can stem, or even reverse, the loss of biodiversity – particularly of plant species – in agricultural landscapes over a relatively short timescale.

Lead author Penny Williams from the Freshwater Habitats Trust says, “The gains we saw are unprecedented for freshwater and are, by a long way, the largest recorded improvements in freshwater diversity seen from adding land management measures to countryside landscapes.

“Our previous work had already shown that ponds were a secret treasure in the British countryside – with a value out of proportion to their tiny size – however the scale of benefits from adding new ponds took all of us by surprise,” Williams continues.

The study is the first major result from the Water Friendly Farming project: a long-term collaboration between the Freshwater Habitats Trust, Game & Wildlife Conservation Trust, the University of York, the Environment Agency and landowners in three Leicestershire catchments.

Dr Jeremy Biggs, the Director of the Freshwater Habitats Trust, says, “This is such an important result: freshwater biodiversity is under threat both across the UK and the globe. Climate change will wreak even more havoc in future years and up to now we have found very few ways to combat losses and make the countryside more resilient.

Biggs adds, “This study is unique because we’ve proven that it’s possible to increase freshwater biodiversity significantly at a regional scale. Up to now benefits have either been very limited, or very local.”

The new ponds created by the project brought back many declining freshwater plants that are almost extinct in the wider countryside including Marsh Arrowgrass (Triglochin palustris), Bristle Club-rush (Isolepis setacea) and Marestail (Hippuris vulgaris). Image: Freshwater Habitats Trust

Ponds increase biodiversity and rare species more than other measures

The project team also tested a number of other management measures in their study catchments, such as adding woody debris to streams, damming ditches to ‘slow the flow’ and trap sediment, and building interception ponds which filtered nutrients and pollutants.

These measures helped stem background plant biodiversity loss (roughly 1% per year), but did not help rare species return to the landscape. Pond creation is shown to have significant biodiversity benefits, whilst remaining cost-effective – each pond cost between £1500-2000 to create.

Prof Chris Stoate from the Game and Wildlife Conservation Trust says, “It’s clear that the key ingredient to success was carefully locating new ponds in places where they would fill with clean water. To get the best effect we sited them in low intensity pasture, scrub or woodland – areas unaffected by agricultural or road pollution. Measures in other locations and with other functions didn’t work half so well.”

The study is the first demonstration of a whole-landscape increase in freshwater biodiversity as a result of management measures in agricultural landscapes. It shows that pond habitat creation can have a positive effect on catchment biodiversity over a relatively short period of time. As a result, the authors emphasise the potential for ‘clean water’ pond creation to help stem, or even reverse, biodiversity loss in agricultural landscapes.


Williams, P. et al., (2020) “Nature based measures increase freshwater biodiversity in agricultural catchments”, Biological Conservation, Volume 244, 108515

Read a briefing note for policy makers and environmental managers on the study findings.