Water and Climate Change at COP21 in Paris
Delegates at the Water Resilience Focus event organised by the Lima to Paris Action Agenda. Image: UNFCCC
This week and next, governments, policy makers and NGOs from around the world are meeting in Paris to work towards a new international agreement on climate change intended to keep future global warming below 2°C. The 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (or COP21) takes place in a year declared the hottest on record by the World Meteorological Organisation.
Water is an key medium through which climate change affects human and non-human lives. Climatically-altered precipitation patterns, extreme weather events (and ensuing floods and droughts), and shifting water temperatures all contribute to alterations in the quality and quantity of freshwater available to humans, plants and animals in ecosystems around the world.
In particular, water scarcity is already posing threats to human livelihoods and freshwater biodiversity. The effects of such water stresses are often uneven, and disproportionately affect poor communities in developing countries with already arid climates (see this UN report, for example, pdf). As such, the interactions of climate change and water have important implications for human poverty alleviation and sustainable development.
The Paris Pact on Water and Climate Change Adaptation. Image: UNFCCC
Whilst some commentators suggested in the run-up to the Paris COP that water would be largely absent from negotiating tables, there have been some encouraging signs. This week, a coalition of national governments, river basin organisations, businesses and civil society groups announced the creation of the Paris Pact on Water and Climate Change Adaptation, intended to make global water systems more resilient to climate impacts.
Announced at a Water Resilience Focus COP event organised by the Lima to Paris Action Agenda on climate change, the Pact represents US$ 20 million in technical assistance and potentially over US$ 1 billion in funding for water and climate change adaptation. It will finance a coalition of almost 290 water basin organisations to implement adaptation plans, strengthen water monitoring and measurement systems in river basins and promote financial sustainability and new investment in water systems management.
The Pact is intended to improve water resources management as a means of making progress towards poverty reduction targets, and achieving sustainable development, for example through Sustainable Development Goals.
Negotiations at the Paris COP are ongoing, and early indications are that there is broad cross-governmental support for significant cuts to carbon emissions. However, UN analysis (pdf) of pre-COP governmental pledges suggests that projected emission cuts may not go far enough to limit increases in global temperatures to 2°C targets by 2100.
For MARS leader Daniel Hering, strong governmental commitments to limiting future climate change in Paris are important for ensuring the health and diversity of global freshwater ecosystems:
“The Intended Nationally Determined Contributions are unlikely to be sufficient for the 2°C target. Any further step in this direction would be a success. However, it is quite obvious that we will have to live with global warming of more 2°C that will greatly affect freshwater quality and quantity.
A bundle of measures to minimise the effects of climate change on freshwater ecosystems are required. In particular, this concerns agricultural practices. For instance, nutrients affect warmer freshwater ecosystems more strongly, so nutrient standards will need to be stronger. River water temperature can effectively be mitigated with woody riparian vegetation, so buffer strips are a key to enhance freshwater ecosystem quality in a warmer world. And agricultural practices saving water will be crucial in arid areas.”
Similarly, MARS scientist Steve Ormerod emphasises the importance of tackling linked climate and water systems during the Paris negotiations. Ormerod, Professor of Ecology at Cardiff University and Chair of Council of the RSPB, describes that whilst encouraging steps are being made, the negotiations face key challenges in promoting resilient and adaptive ecosystems under climate change:
“All the evidence we have is that freshwater ecosystems are among the most sensitive of all to climate change: we know that they are warming, that their patterns of floods and droughts are changing, and that their organisms are being affected. In the end, this is bad news for people – because freshwaters are the ecosystems that we depend on more than any other.
I’m very glad there is at least some emphasis on freshwater at #COP21 – for example the Paris Pact on Water and Climate Change Adaptation focused on making our freshwater ecosystems more resilient across very large areas of the world.
Conservation organisations such as the IUCN are pushing for the protection of “natural infrastructure” in river catchments and riparian zones as a means of making freshwaters more resilient. These concepts are supported by our own evidence – for example showing how riparian woodlands in temperate areas can ‘climate-proof’ rivers against future change.
But we should have no illusions about the magnitude of the challenge ahead. We are entering an epoch where pressures on freshwaters for water supply and for food production have never been greater. Sound, science-based management will become more critical here than anywhere, and we can only prevent catastrophe if scientists, policy makers and stakeholder engage fully in solving the problems of water – potentially our greatest problems of all.”
We’ll continue to follow the negotiations at the Paris COP and report back at the end of next week with their outcomes.
A Mediterranean river: the Fango Valley in Corsica. Image: Ole Reidar Johansen (Flickr | Creative Commons)
Rivers are often receptacles for substances used and emitted by humans living across their watersheds. Fertilisers, pesticides, pharmaceuticals and new substances such as microplastics and nanomaterials may be carried through drains and outflow pipes, along roads, pavements and fields, and through rock and soil to reach a river.
Here, pollutants can impair the health and functioning of the river ecosystem in a number of ways. Such effects are complex, and may occur in interaction with other stressors on the river ecosystem such as alterations of water flow and temperature, habitat loss, climate change and invasive species (see the recent MARS video on the subject).
The interactions and effects of such multiple stressor ‘cocktails’ on river ecosystems are still only partially understood by freshwater scientists. In this context, a new issue of the journal Science of the Total Environment features 44 scientific papers on multiple stressor effects on rivers, particularly focused on Mediterranean river basins and water scarcity.
The special issue, titled “River Conservation under Multiple stressors: Integration of ecological status, pollution and hydrological variability” is edited by Marta Schuhmacher from the Universitat Rovira i Virgili and Alicia Navarro-Ortega, Laia Sabater and Damià Barceló from the Spanish Council for Scientific Research Institute of Environmental Assessment and Water Research.
Between 2009-14, the editorial team were members of the Spanish government-funded SCARCE project, which assessed and predicted the effects of global environmental change on water quantity and quality in Iberian rivers.
The final SCARCE conference, held in October 2014 in Tarragona, was attended by many partners of the European Union funded GLOBAQUA project. Both projects have common interests in considering water scarcity as the main stressor in river systems. The Tarragona conference integrated many of the findings and data from the SCARCE project with ongoing GLOBAQUA activities, which in turn have been translated into journal articles in the new special issue.
There is a rich variety of articles in the issue, covering numerous different multiple stressors scenarios in ecosystems across the world, and assessing strategies for their experimental study and management. Earlier in the year, we covered a study published in the special issue by MARS scientists led by Peeter Nõges on biotic and abiotic responses to multiple stress.
You can read the special issue of Science of the Total Environment online here
UK Government taken to court over freshwater pollution
Crop spraying at Swaffham Lock, Cambridgeshire. Image: Hugh Venables, Creative Commons, from Geograph.
Today the Angling Trust, Fish Legal and WWF-UK have joined together in the High Court in London to challenge “a governmental failure” to prevent agricultural pollution in UK freshwaters.
The organisations have tabled a judicial review that argues that the UK government has failed to stop agricultural pollution from degrading 44 rivers, lakes and estuaries.
They argue that under the EU Water Framework Directive, the UK government is required to ensure that these freshwaters are in good health by the end of 2015. However, this deadline is unlikely to be met.
Campaigners are using the legal action as a means of pressuring the government to implement stronger environmental policies which promote the health and diversity of UK freshwaters.
Writing on the Angling Trust blog, Chief Executive Mark Lloyd attributes the poor health of many UK freshwaters (where, for example, only 17% of rivers are in ‘good health’) to a governmental failure to regulate agricultural practices:
“Rain landing on wet, compacted fields runs off the surface of the soil and into rivers, carrying with it slurry, soil, pesticides and fertilisers, all of which are lethal to fish and the invertebrates they eat. Badly maintained gutters allow rainwater from roofs to wash farmyard muck into drains. Broken pipes divert filthy water into streams. All these trickles add up to a mighty load of pollution. Just because it doesn’t come out of a big pipe doesn’t make it any more deadly to our aquatic wildlife. It’s often referred to as causing death by a thousand cuts.”
In particular, the coalition of organisations argue that the government has failed to implement any Water Protection Zones (pdf), the locally-specific policy approaches designed in 2009 to tackle agricultural pollution as part of River Basin Management Plans.
David Nussbaum, Chief Executive of WWF-UK argues that such decisions have overlooked the importance of freshwater ecosystems, which has prompted today’s legal action:
“This was an ideologically driven decision, taken behind closed doors, which contravened the Government’s public position. It also flies in the face of Defra’s own analysis which has repeatedly shown that relying on voluntary action by farmers alone will not solve the problem of agricultural pollution.
We believe the use of this ‘last resort’ doctrine to evade installing Water Protection Zones has not only been devastating for our protected rivers and wetlands but is also unlawful.
Worse still, with these specially protected sites continuing to be polluted it is baffling that Water Protection Zones are still not being used as we approach the December 2015 deadline – if this doesn’t count as a time of ‘last resort’, what does?”
Responding to the judicial review, a Defra spokesperson told The Guardian that:
“Rivers in England are the healthiest they have been for 20 years and we are committed to working closely with the farming community and environmental groups to further improve water quality. Over the next five years, we are investing more than ever to promote environmentally friendly farming practices to protect our rivers and lakes and support wildlife.”
In October 2015, the European Commission issued legal guidance that warned the UK government of its failures to implement EU water legislation, which could potentially lead to fines of millions of pounds a year.
Update 20.11.15: High Court rules that the UK government must evaluate the use of mandatory Water Protection Zones. Read more on the WWF website.
New film tells the story of Devon’s wild beavers
We wrote last year about the population of beavers found living on the River Otter in Devon in south-west England. These were the first wild communities of beavers found since hunting drove the animal to extinction in the UK in the 1700s. Earlier this year, the first baby beavers – known as kits – were born on the river (watch footage of them here).
The Devon Wildlife Trust, who monitor the beaver population, have recently released a short film documenting their work and the impacts of the animals on the local environment and communities. The film outlines how the Devon beavers are valuable ‘ecosystem engineers’ of new habitats in and around the river, have become a draw for ecotourists, and a focal point for local environmental education schemes.
A Swedish boreal lake. Image: Erik Jeppesen
The world’s lakes, rivers and reservoirs naturally emit carbon dioxide as part of the global carbon cycle. Recent scientific studies suggest that annual carbon dioxide emissions from inland freshwaters roughly equate to the total uptake of carbon by the world’s oceans.
However, a new study using extensive ecological data from 5,000 Swedish lakes suggests that ongoing changes in land use and climate are causing increased levels of dissolved inorganic carbon in northern boreal lakes, which in turn is causing the lakes to emit increasing amounts of carbon dioxide into the atmosphere.
Writing in Nature Geoscience, Gesa Weyhenmeyer from Uppsala University and colleagues observed that small lakes in southern Sweden emitted twice as much carbon dioxide as equivalent small lakes further north. The team documented that carbon dioxide emissions were highest in lakes with a significant number of ice-free days each year and high dissolved oxygen and nutrient concentrations (often as a result of agricultural runoff).
Co-author, and MARS partner, Erik Jeppesen from Aarhus University explains,
“Our work indicates that the release of carbon dioxide from lakes in Sweden will increase as the climate gets warmer, and as areas adjacent to lakes is used for agriculture in the place of forests.”
The burning of fossil fuels releases carbon dioxide, and scientific consensus is that the resulting increase in atmospheric CO2 concentrations is causing increased global temperatures and other ongoing climatic changes.
The new study by Weyhenmeyer and colleagues shows that dissolved carbon from such emissions can travel through a watershed and ‘supersaturate’ lakes, which in turn causes them to emit carbon dioxide into the atmosphere. They suggest that carbon emissions from some of the boreal lakes in southern Sweden have reached levels comparable to lakes in tropical regions. In effect, this is a climatic feedback loop, where climate change drives further increases in CO2 emissions from freshwaters.
As a result, boreal lakes in northern latitudes of the world may become increasing sources of atmospheric carbon dioxide, a prospect that has consequences for global climate change, as Erik Jeppesen outlines,
“The findings worry us. There is great risk that as the climate warms in coming years, carbon dioxide emissions from lakes will increase significantly in the northern parts of Scandinavia, Russia and Canada. And, of course, these regions are where the vast majority of the world’s lakes are.”
For lead author Gesa Weyhenmeyer, the team’s findings have important implications for how we understand, and manage, boreal freshwater ecosystems as part of increasingly human-altered global climate systems,
“When we assess future emissions of carbon dioxide to the atmosphere, it is important to know where the carbon dioxide comes from. Only with this knowledge can we find ways to reduce the release.”
Weyhenmeyer, G. A., Kosten, S., Wallin, M. B., Tranvik, L. J., Jeppesen, E., & Roland, F. (2015). Significant fraction of CO2 emissions from boreal lakes derived from hydrologic inorganic carbon inputs. Nature Geoscience, advance online publication.
SOLUTIONS for open-data publishing
Guest post by Steffen Neumann, David López Herráez and Werner Brack.
Since the earliest days of science, journal articles have been the centre of scientific communication. They are the source of information in which academics, policy makers and businesses know what is happening in – and can build upon – the important research in their field. With online publishing, scientists can now collaborate more than ever before, sharing not just brief overviews of their methodology and results in print articles, but also their full results, primary datasets and even interactive graphics, all as “supplemental data”.
Supplemental data may help make scientific research more reliable (as experiments can be easily and properly replicated and fact-checked), efficient (as similar datasets are shared across different users, rather than having to be created multiple times from scratch), and democratic and transparent (as expert statements are open to public scrutiny). Despite this, it can sometimes seem like authors, editors and reviewers currently neglect the huge promise of supplemental data.
This was one of the topics under discussion at last month’s second annual general assembly of the SOLUTIONS project. This EU funded project is an international collaboration of academics, policy makers and businesses, all working to solve the problems of chemical pollution in European rivers and lakes. Getting the most out of the relevant science is a hugely important aspect of SOLUTIONS’ work, and one in which good supplemental data could play a vital role.
After discussion at the recent general assembly, SOLUTIONS members Maria König, Miren López de Alda, Bozo Zonja, Francesco Falciani, Steffen Neumann and Tobias Schulze created a report entitled “What makes good Supplemental Data and how to get there?” The report gives the following advice to scientists on using supplemental data to create better science that can be used more effectively to support environmental protection.
Attendees at the SOLUTIONS general assembly. Image: SOLUTIONS
Who uses supplemental data, and for what?
Perhaps one of the original aims of supplemental data was to add supplemental information that would not fit into the prescribed, say, eight pages of the main manuscript. In essence, these types of supplemental information are like an extension to the paper.
An important example of an area where supplemental data can really shine is meta-studies. These syntheses rely on being able to extract information from scientific studies in an efficient way. This could mean a lengthy process of contacting dozens of authors to obtain the required data. With good supplemental data, however, access can be instantaneous – making meta-studies not only better scientifically, but also cheaper and more efficient.
Another example is people searching for the best available method for a new study. Very often, journal papers report that some method performs this-and-that better than another method, or is faster, or cheaper, or all of these. Good supplemental information allows potential users to be able to make an informed, unbiased comparison of potential research methods.
Supplementary information can also allow a scientific finding to reach relevant audiences beyond the authors’ immediate peer group. A bioinformatics specialist, say, might be able to use the findings of a new chemistry study to create a better model of watershed pollution. However, he/she may not have the actual knowledge of chemistry necessary to make immediate sense of the article. Good supplementary information can provide the background information necessary for interdisciplinary (or even within-discipline) translation.
What is good practice for the use of supplemental data?
If you have any graphs or diagrams in your article, one of the first things you should have in your supplemental data is the actual data your figures are based on. This means someone else can reproduce the same graphics (even if this is only because they want it in another colour!) Spreadsheets or plain CSV files are the best format for this “real data”. Some useful recommendations for suitable archive formats can be found here.
If you’re reporting chemical compounds, you should provide an identifier – not only the name or CAS number. Deriving further chemical and physical properties from a name can be extremely tedious (or impossible) to do it unambiguously. Instead, you can use more detailed identifiers like PubChem CID or ChemSpider CSID, or descriptors like SMILES, InChI, InChIKey. If your datasets are too large for the publishing journal’s supplemental section, there are community-accepted repositories you can use, such as FigShare, Dryad and others.
The new SOLUTIONS report suggests that journal guidelines often give submitters little to no information about what to include in the supplemental data. So how do scientists learn to create good supplemental data?
The report suggests taking note of what works – and what doesn’t – in existing journal articles, and using in-house or departmental peer-review processes to check not just the proposed article, but its supplemental data too. Likewise, based on these recommendations, community advocacy could persuade journals to offer guidelines regarding minimum requirements and/or format their supplemental data should have. As a user-oriented, interdisciplinary project covering a huge range of chemical pollutants across the entire European Union, SOLUTIONS will be working hard to provide best practice examples of how supplementary data can be used to help science work better and faster to protect the environment.
Shaping the Future of UK Upland Environments
Upland communities of people, plants and animals that live on the UK’s high hills, lakes, rivers and moors are under increasing pressure. Whilst uplands form a large proportion of the UK’s land area (around 40%), they are often challenging places for communities – both humans and non-humans – to survive.
A lack of rural jobs coupled with the dwindling profitability of agricultural practices in many upland areas of the UK has put strain upon traditional communities. Upland areas are on the leading-edge of climate change in the UK, as the climate niches in which communities of plants and animals – many of them rare or endemic – live are moved slowly upwards in altitude until potentially little or no suitable habitat remains.
For example, upland peat bogs – a crucial store of carbon and regulator of water flows in the landscape – require cool, wet conditions to regenerate. Studies such as this 2013 report led by Professor Colin Prentice of Imperial College London suggest that future climatic change in the UK is likely to cause peat bogs to shrink – which when coupled with human degradation of peat bog landscapes through overgrazing and cutting is likely to have widespread effects on the ecological health of the wider upland environment.
As the figure below shows, upland landscapes provide a range of important ecosystem services to humans and support unique assemblages of plants and animals, making their ongoing sustainable use and management a key issue.
A new report led by the DURESS Project based at Cardiff University in Wales assesses the potential impacts of four different upland land-use scenarios on UK upland communities towards 2050. Funded by the Biodiversity and Ecosystem Sustainability (BESS) programme of the Natural Environment Research Council, the report assesses the consequences of four possible scenarios for UK upland landscapes over the next 35 years: Agricultural Intensification; Managed Ecosystems; Business as Usual; and Abandonment.
The scenarios were developed through analysis of the drivers of environmental change, both local (e.g. food markets, farming practices and hydro-schemes) and global (e.g. climate change, global food and timber markets and EU environmental policy), and the probabilities for their different paths of development over the next 35 years. These projected scenarios were supported by a process of ‘backcasting‘ in which historical environmental changes to the uplands since 1945 were analysed.
Each of the four projected scenarios has different environmental drivers and outcomes. The Agricultural Intensification scenario is projected to occur if global food security forces UK policy makers to focus on production, making hill farming an important contributor to the national livestock industry and limiting environmental protection to comply with the demands of the market. Here, riparian zones along rivers are likely to be removed to create more grazing land, alongside an increased input of fertilisers, chemicals and pesticides into upland rivers: creating new cocktails of multiple stress on aquatic life.
The Business as Usual scenario is projected where UK environmental policy aims to balance the aims of agricultural productivity and environmental protection. Here, upland farming does not contribute to UK food security, and environmental protection is based on a limited amount to small areas of land such as national parks and protected areas, areas with high tourism value, or areas requiring specific protection to meet regulations. Agri-environmental schemes are likely to help improve the health and diversity of upland rivers, but there will be difficulties in creating connected, landscape-scale environmental management schemes.
The Managed Ecosystem scenario is projected where carbon and biodiversity management becomes the dominant management paradigm in upland landscapes and environmental policy is focused on restoring peatlands, and expanding wetlands and woodland to regulate soil carbon loss and increase biodiversity. Whilst reliance on overseas areas for provisioning services (fuel, fibre and food) may increase, upland ecosystems will benefit from reductions in livestock grazing pressures and reduced erosion and pollution.
Finally, under the Abandonment scenario, existing upland policies become too costly to implement because of competition for public funds for other priorities and the lack of viable markets for products and services. The sustainability of farming enterprises decreases due to the loss of familial farm succession and poor uptake of new technology and practices. Declines in farming activity and upland livelihood opportunities leads to eventual agricultural abandonment. With grazing pressure removed, it is likely that upland ecosystems will undergo a process of ‘rewilding‘ to greater ecological health and diversity. (although as many recent studies have shown, the tangents of such environmental change are likely to be complex and difficult to predict).
DURESS is a project focused on promoting diversity in upland rivers as a means of improving their ecosystem service sustainability (watch their new Shaping Our Future film above). As such, river ecosystems are placed at the centre of the projected scenarios in the report, as a means of informing environmental managers on upland decision making. For each scenario, maps are created to show where land cover change would occur, the magnitude of this change, and its likelihood.
Rather than offering firm recommendations, the new Upland Scenarios report is framed as a ‘stock-take’ of ongoing DURESS research, part of which will inform the MARS catchment modelling work. It suggests that UK upland economies – particularly farming – are fragile and heavily dependent on national and European subsidies to continue. As such, the report ends with the question of whether rural economies can be managed by UK government policy to promote ecosystem services such as water resources, flood management, carbon sequestration, renewable energy and biodiversity. Balancing such environmental goals with issues of dwindling and aging rural populations, fragile economies and ecosystems gradually affected by climate change is likely to pose significant future challenges for UK policy makers and environmental managers.
A human-made weir on a UK river. Image: River Obstacles
Flows of water in rivers and streams across the UK are diverted over, under, through and around many different obstacles. Some of these are formed naturally – for example waterfalls – whilst others are human-constructed, such as dams, sluices and weirs.
As we’ve discussed in a number of posts (here and here, for example), whilst such human-made obstacles can have societal benefits (such as hydropower generation), they often have negative ecological effects: fragmenting fish migration routes, causing bank erosion, changing habitats and altering water and sediment flows.
An innovative new smartphone app has recently been released to allow members of the public to log the location and type of river obstacles – both natural and human-made – in UK rivers. River Obstacles has been jointly developed by the Scottish Environment Protection Agency (SEPA), the Rivers and Fisheries Trust for Scotland (RAFTS), the Environment Agency (EA) and the Nature Locator team.
The free River Obstacles app allows river users such as anglers, canoeists and walkers to log the details and submit photographs of obstacles such as dams and weirs. The data from these ‘citizen hydrology’ submissions will help map obstacles in regions where there is currently very little information (such as in remote areas), or where obstacles have recently been built or damaged.
The crowdsourced data submitted through the app will allow environmental managers and policy makers to identify redundant human-made obstacles that can be removed from rivers, and prioritise improvements to other obstacles that will yield significant environmental improvements. Information on natural obstacles will also be used to determine the natural limits to movement for different species of fish.
Environmental data submitted by members of the public has been growing in popularity over the last five years or so in the ‘citizen science’ movement (see our interview with Helen Roy from the Centre for Ecology and Hydrology on the subject).
Public sourced information on the natural world – increasingly facilitated by advances in mobile technology – has a number of potential benefits: for example, creating data for areas where scientists may not have sampled and engaging members of the public with processes of environmental monitoring and management (see another, older post on the subject from back in 2010).
This is the first time we’ve seen this technology used to crowdsource hydrological data, making River Obstacles an innovative and interesting initiative. We’ll keep you updated with its results.
River Obstacles
Download for iPhone and Android
Using microscopic fungi to understand the impact of dams on rivers
The River Bienne in the Jura Mountains, Eastern France: the region in which this study was undertaken. Image: KlausFoehl | Wikipedia
Dam construction often causes a range of stresses to the health of river ecosystems and the biodiversity they support. Despite their value to humans in terms of drinking water supply or hydropower generation, dams can change the course, speed and amount of water that flows in a river. As such, dams can exacerbate droughts and flashy floods (see, for example). Dams can also fragment migration routes for fish such as salmon and sea trout, and alter nutrient and sediment flows along the course of a river.
However, the ways in which the multiple stresses caused by dams interact and impact river ecosystems is still not fully understood. In particular, understanding the ways that dam construction affects the functioning of an ecosystem (i.e. all the processes that take place to maintain the health and diversity and the services it provides) is of particular interest to freshwater scientists. What is needed are bioindicators that scientists can use to identify both early (i.e. detecting first signs of alteration) and predictive (i.e. identifying effects on ecosystem functioning and provision of ecosystem services) impacts of ecosystem change as a result of human activity.
In this context, a new study by Fanny Colas from the University of Toulouse and colleagues examines the value of fungal growth from leaf litter breakdown as a bioindicator for changes in ecosystem function in response to multiple stresses from dams. Leaf litter breakdown is a good indicator of ecosystem functioning: partly because it is a key process in rivers and streams, releasing nutrients through food webs; and partly because it is well-studied and understood by scientists.
Microscopic image of Clavariopsis aquatica, an aquatic hyphomycete which breaks down leaf litter. Image: Wikipedia
Leaves that falls into streams and rivers are generally broken down by two types of organisms: microorganisms such as fungi; and aquatic invertebrates. In this study, the team led by Dr Colas focused on a group of fungi called hyphomycetes, which are early colonisers of leaf litter. Hyphomycetes cause the initial breakdown of leaf litter, which in turn makes it more palatable and nutritionally valuable to aquatic invertebrates. So, changes in the growth and activity of fungal hyphomycetes could lead to altered leaf litter breakdown, and changes to the resulting flows of energy and nutrients through the ecosystem.
Publishing in Ecological Indicators, the team investigated the effects of small ‘run of the river‘ dams (lower than 15 metres) on fungal richness and biomass on decaying leaves both above and downstream of the dam wall. They conducted field sampling on dams at nine sites in Eastern France alongside laboratory experiments to assess the response of microbes associated with decaying leaf litter to multiple stressors resulting from dams, and the consequences for the health and functioning of the wider river ecosystem. In the European Union such small dams are not fully addressed by the Water Framework Directive, yet there are many of them: more than 76, 292 small ‘run-of-river’ dams have been identified in France alone by the French National Agency for Water and Aquatic Environments.
The team found that the presence of a small dam reduced the biomass of fungi, both in the upstream reservoir and downstream river. This is thought to be because dam construction restricts the downstream flows of leaf litter, sediment and other detrital resources, and alters the communities of aquatic insects and microorganisms involved in leaf litter breakdown. Interestingly, they also observed a significant decrease in fungal biomass downstream of reservoirs with sediments contaminated by metal pollutants.
Decomposing leaves are an important source of nutrients and energy to river ecosystems. Image: Wikipedia
Reductions in hyphomycete fungi are likely to have implications for higher trophic levels in freshwater ecosystems, by modifying the effectiveness of both fungi and leaf-shredding invertebrates in processing leaf litter. As such, the authors term describe how reduced fungal growth can have negative ‘cascading effects’ on the wider ecosystem.
Delayed or reduced leaf breakdown is likely to lead to the accumulation of non-rotted organic material in reservoirs above dam walls, reducing water quality and the amount of nutrient and carbon available. It is important, therefore to note that the functioning of the reservoir ecosystem has consequences for the water quality, health and function of downstream ecosystems.
Colas and colleagues’ study highlights the sensitivity of the hyphomycete fungi to the multiple stressors associated with dams and reservoirs. They conclude that fungal indicators could enable scientists to predict changes in ecosystem functioning because of their positive relationships with the effectiveness of fungi and leaf-shredding insects in breaking down leaf litter. These relationships may also be used by environmental managers seeking to understand the vulnerability of ecosystems to the multiple stressors caused by dam construction.
In short, their study suggests an intriguing possibility: that by studying tiny fungal microorganisms, scientists might be able to better understand – and even predict – the ecological effects of large dam engineering projects that fundamentally change the nature of rivers.
The Invisible World: a new film exploring UK freshwater life
The Salmon and Trout Conservation UK charity has this week announced the outcome of its £2,000 “Invisible World’ filmmaking competition. Scottish filmmaker Andrew O’Donnell’s entry was judged the winner by a panel including award-winning wildlife film-makers Hugh Miles, Paul Reddish and Charlie Hamilton James, television personality Matthew Wright and Salmon and Trout Conservation CEO Paul Knight.
The Invisible World competition was launched back in February, to encourage filmmakers to create work that engaged with the invisible beauty and diversity of freshwater ecosystems, and the similarly often unseen threats that they face. Hugh Miles explained why O’Donnell’s film (also titled The Invisible World) came out on top, “It is the most imaginative interpretation of the subject and says all the right things about water. It succeeds really well in linking ‘our’ world with the ‘invisible’, so bravo for the great effort and hard work that went into this production.”
O’Donnell’s film has a sparkling clarity about it, and the aquatic environments he filmed – both above and below the surface – are captured in sharp, perceptive focus. The making of his prize-winning entry was a long and (quite literally) immersive process: “I initially noticed the competition on S&TC UK’s website, whilst doing some research for another project. It appealed to me instantly as I’m very passionate about all the elements of the brief – the beauty, wildlife and threats to the UK’s freshwater environments.”
“The film took around 8 months to make and I travelled all over the UK filming it. My wetsuit was put to use a lot more than usual! I wanted it to show how much people rely on our freshwater environments. We all use them in one way or another. It’s not just people who are involved in aquatic based activities who should be protecting these environments. It’s everyone!”
More information on the Invisible World film
Salmon and Trout Conservation UK
The Freshwater Blog 