MARS Experiments: Low Flows in Nordic Rivers
The experimental channels. Image: Aarhus University
Over the last few weeks we’ve been introducing the experiments that the MARS research team have been carrying out across Europe to understand the effects of multiple stresses on freshwater ecosystems. This week we turn our focus to Denmark, where a team led by researchers led by Annette Baattrup-Petersen and Daniel Graeber from Aarhus University are investigating the effects of low water flows on freshwater streams.
Low stream flows, the build up of fine sedimentation, and eutrophication – caused by dissolved nitrogen and phosphorus – are the main stressors of stream ecosystems in Nordic agricultural landscapes. In these experiments, the MARS researchers seek to understand how these stressors affect small stream ecosystems in these landscapes, particularly focusing on how the stressors might interact. Research in this area is particularly important given that predictions of future climate change suggest that many rivers in northern Europe will experience longer periods of low flows, due to changing precipitation patterns and climate warming.
Experimental channel diagram. Image: Aarhus University
The MARS team are currently conducting a series of measurements and experiments, seeking to couple stream ecosystem structure to ecosystem function, from which the potential effects of stress on ecosystem services can be derived. The research team have constructed 12 experimental stream channels, 12 m long, 0.6 m wide and 0.3 m deep, which are designed to simulate natural small stream ecosystems and the effect of multiple stressors. The stream channels consist of a series of runs and riffles with sediment typical for such habitats. They are fed by stream water, which results in natural water chemistry and also brings new algae, water plants and invertebrates into the experiment (as would happen in a real stream). The flow of water down the channels can be controlled to simulate normal and low stream flows.
Runs and riffles on the experimental channel. Image: Aarhus University
The MARS team are focusing their attention on two key components of small stream ecosystems: benthic invertebrates and benthic algae, with a focus on primary production and nutrient uptake as ecosystem functions. Benthic algae are the main primary producers in small stream ecosystems and provide food for grazers, such as benthic invertebrates, as well as oxygen for all animals and fungi. Benthic invertebrates are the main food source for fish in Danish small streams and can control the growth of benthic algae by feeding on them. Therefore, the combination of all elements of a stream ecosystem defines its capability to take up and therefore retain nutrients.
To measure primary production in the sediments and on stones, the team use specially made experimental chambers, and take samples for algal biomass and composition and benthic invertebrate density and composition. To measure nutrient uptake, the team initiate short-term nutrient releases for ammonium, nitrate and phosphorus, and measure the ecosystem response.
A stone covered in sediment in an experimental channel. Image: Aarhus University
Three stressors in the experiment:
The three chosen stressors are likely to have several effects on the interaction of benthic invertebrates and algae in the experiment.
Low flow is likely to result in a reduction of densities of typical stream benthic invertebrates (mayflies, stoneflies) many of which are grazers. Similarly, due to less physical abrasion on the streambed, low flows are likely to result in higher benthic algae growth. Combined with the reduction of stream benthic invertebrates, a higher primary production can be expected and due to the longer residence time (i.e. the amount of time a particle spends in a system), nutrient uptake should also increase.
Eutrophication is known to increase the biomass of benthic algae due to higher nutrient availability and will likely result in higher primary production and higher nutrient uptake. Based on existing scientific literature, eutrophication is likely to have minimal effects on benthic invertebrates.
Fine sedimentation severely affects benthic algae simply by covering them and by removing suitable habitats (coarser sediment), which are buried by fine sediment. Fine sediment also affects benthic invertebrates by clogging the room between coarser sediment particles and removing the access of scraper invertebrates (see the FSC guide to invertebrate feeding methods) to their food source (benthic algae). Finally, fine sediment delivers a large amount of organic matter to the stream, which is expected to strongly increase benthic respiration – which removes oxygen – and thus may counterbalance the effects of algal primary production.
We will keep you updated with the results of this experiment, and the others that the MARS team are carrying out across Europe. You can find links to all the MARS experiment blogs here.
Small is beautiful: the overlooked importance of small freshwaters
A pond in Hampshire, Southern England. Image Anguskirk, Flickr
Small bodies of water such as ponds, ditches, springs, flushes and headwater streams pockmark many landscapes across Europe. Whilst they might often be overlooked (stepped over, sometimes), there is increasing consensus that these small freshwaters are extremely important to the ecological health of the landscape.
European ponds, for example, support a larger proportion of freshwater biodiversity than lakes or rivers, and help ‘connect’ a landscape for species such as frogs and dragonflies by providing a series of ‘stepping stone’ habitats across the wider landscape. In this way, small water bodies are important as part of what ecologists term the ‘landscape matrix’, providing patches of diverse habitat (often in urban and non-protected areas) which interconnect with other ecological processes across the whole landscape to shape its overall health and diversity. Headwater streams (those right at the top of the river’s course) can provide spawning grounds for fish like the Atlantic salmon, and then sheltered ‘nursery’ habitats for their offspring.
However, small water bodies have been largely ignored by freshwater scientists, conservationists and policy makers, meaning there are gaps both in our knowledge of their ecological forms and functions, and in their protection through policies like the Water Framework Directive. There is growing awareness of the significance of small water bodies, shown by their inclusion in the European Environment Agency’s European waters – assessment of status and pressures and the European Commission’s Blueprint to Safeguard Europe’s Water Resources, both published in 2012.
As part of this increasing focus on small water bodies, The European Environmental Bureau and the Freshwater Habitats Trust recently released a report on a workshop which took place in November 2013 to discuss how small water bodies might be better managed and protected in Europe.
A key issue discussed at the meeting was how existing European legislation – particularly the Water Framework Directive, Birds and Habitat Directive and the EU 2020 Biodiversity Strategy – could incorporate small water bodies. Another was the need for effective co-operation between different environmental managers across the wider landscape to better understand, monitor and manage the role of small water bodies in supporting biodiversity on a landscape scale. Finally, small water bodies were seen as ideal habitats for engaging the public with conservation issues, given that ponds and streams are present in most landscapes, even those that are predominantly urban.
You can read the workshop report on the Freshwater Habitats Trust website, and find out more on the European Environmental Bureau website.
When the MARS project was launched in the sunny climes of Mallorca in February 2014, Dr Christian Feld interviewed a number of freshwater scientists and policy makers attending the kick-off meeting. In the above video, Christian interviews Rolf Altenburger from the Helmholtz Centre for Enviromental Research (UFZ) in Leipzig, Germany. Dr Altenburger is deputy co-ordinator of the SOLUTIONS project which studies the effect of chemical pollutants on freshwater quality and ecological health, and aims to provide solutions to help manage and protect Europe’s freshwaters.
In this video, Dr Altenburger describes how the project’s focus on the impact of stressors on the freshwater environment links SOLUTIONS with the MARS and GLOBAQUA projects (see our earlier blog and interview here). As Dr Altenburger explains, there are more than 100,000 chemicals in daily use across the world, which come from sources such as agriculture, pharmaceuticals, food additives, plastics and cosmetics.
Animals and plants living in freshwater ecosystems are increasingly exposed to a complex mixture of diluted chemicals (referred to as ‘cocktails’ by Dr Altenburger), which makes identifying and managing their effects – both individually and together – a difficult task. This is further complicated by the sheer number of chemicals which are potentially harmful to freshwater ecosystems. At present, the monitoring systems in place are not detailed or comprehensive enough to assess and manage the huge diversity and complexity of chemical ‘cocktails’ that are increasingly present in freshwater environments, many of which are new or unknown.
Chemical pollutants may interact with other stresses on freshwater environments. For example, water scarcity (as seen on the Iberian peninsula) increases chemical concentrations in the remaining available water, which would otherwise be diluted by normal flows, with potentially harmful effects on water quality and freshwater life. Understanding the impact and interaction of multiple stressors is a key EU research topic at present, in an effort to strengthen the Water Framework Directive, which is why the MARS, GLOBAQUA and SOLUTIONS projects are collaborating closely.
SOLUTIONS seeks to better understand, predict and manage the effects of chemical pollutants on freshwater environments. Achieving this requires the development of a consistent framework to monitor and assess chemical pollution, particularly in increasing efficiency and speed of chemical identification from complex ‘cocktails’ and at low concentrations.
SOLUTIONS will produce computer models to help environmental managers and policy makers predict the effects of chemical pollution on freshwater biodiversity and water quality in the future, allowing forecasts to be made under changing economic conditions, new technologies, shifting human development and climate change. This production of user-friendly resources and a common chemical knowledge base will also help will help bring chemical pollution up the European policy agenda ahead of the potential revision of the Water Framework Directive in 2019. It will also help create early warning systems for future chemical pollution across the continent.
The models and tools developed by SOLUTIONS are being trialled and tested in three river basins across Europe. New approaches to identifying river basin specific pollutants are being applied along the Danube basin in Central and Eastern Europe, following the extensive Joint Danube Survey 3 along the river in 2013. In the Rhine basin in Central Europe, new wastewater and drinking water treatment technologies are being assessed, to understand their effects on chemical pollutants in the basin. Finally, the risk posed by chemical pollution under water scarcity conditions are being studied in the Ebro and Llobregat basins in northern Spain.
More information on SOLUTIONS:
A new way of publishing information on freshwater datasets
The Freshwater Metadata Journal on the iPad. Image: Astrid Schmidt-Kloiber
The Freshwater Metadata Journal – the first journal set up to exclusively publish the metadata of freshwater related datasets – was launched online on October 8th by editor-in-chief Astrid Schmidt-Kloiber from BOKU in Vienna.
Metadata describes how, why and when a dataset was collected; by who and for what purpose; alongside any intellectual property rights (see an earlier Freshwater Blog post on the topic here). Metadata provides a rich set of contextual information about a dataset, which is very useful to researchers undertaking new analyses and applications of the data itself. The value of metadata – the ‘data about data’ – to the ecological sciences is increasingly well recognised and collecting such data is gradually becoming more common in the scientific community.
However, publishing metadata can be seen as “non-scientific” work and established scientific journals are often reluctant to release articles exclusively focusing on the description of a dataset. At the same time, there is a growing need for researchers to be able to easily locate existing scientific datasets for large-scale analyses whilst encouraging the re-use of datasets collected with public funds, which might otherwise be inaccessible.
The Freshwater Metadata Journal is a response to this need and seeks to link scientific research articles with the data they use. It provides researchers and data managers with an online, fully automated process to easily publish freshwater (biodiversity) related metadata, providing a simple way for scientists to describe and contextualise the data used in their work. All information on datasets is open-access with an assigned digital object identifier (DOI), which makes them easy to trace and cite within the scientific community.
The journal was initiated through the work in BioFresh – an EU-funded project that compiled together the widely dispersed information about life in our rivers and lakes, to better understand, manage and protect our freshwaters for generations to come. BioFresh launched the related Global Freshwater Biodiversity Atlas earlier in the year. The journal was developed at the Institute of Hydrobiology and Aquatic Ecosystem Management (BOKU) in cooperation with the Royal Belgian Institute of Natural Sciences in Brussels.
For more information contact the editor-in-chief:
Dr. Astrid Schmidt-Kloiber
Institute of Hydrobiology and Ecosystem Management, BOKU
Tel.: +43-1-47654-5225
E-Mail: astrid.schmidt-kloiber@boku.ac.at
MARS Experiments: Peak Flows in Alpine Rivers
The Hytech experimental channels in Austria. Image: Christian Feld
The MARS project is carrying out seven long-term experiments across Europe to study how river and lake ecosystems respond to multiple stresses. Last week, we profiled the experiments on Peak Flows in Nordic Rivers which are being carried out near Trondheim in Norway. This week, we introduce the work of a team led by researchers at the University of Natural Resources and Life Sciences (BOKU) in Vienna, Austria on ‘Peak Flows in Alpine Rivers’.
As in the experiments in Norway, the BOKU research team in Austria are interested in understanding the effect of extremely high water flows on the freshwater environment. Here, the team are seeking to understand the effect of sudden releases of water from hydropower plants (or ‘hydropeaks’) on the ecology of Alpine rivers, specifically in fish, insects and algae communities.
Researchers electrofishing. Image: Christian Feld
Hydropower has become big business in the Alps, generating renewable energy using the force of rivers flowing strongly down steep mountain sides. However, this approach to ‘green’ energy production brings a range of potentially harmful effects on freshwater life – affecting the flow speed and amount, the water temperature and the physical characteristics of the river (its ‘morphology’) amongst others. These potentially harmful stresses on the freshwater environment are strongest where there is no compensation reservoir to buffer flow fluctuations from hydropower releases.
It is estimated that around 800km of Austrian rivers are significantly affected by hydropower developments. However, the effects of hydropeaking on freshwater environments are not fully understood. As a result, the BOKU team are using a two experimental channels at the HyTEC (Hydromorphological and Temperature Experimental Channels) facility in Lunz am See, Austria to carry out research on the topic.
Mesocosms on the experimental channels. Image: Lisa Schülting
The changes in water amount, speed and temperature associated with a ‘hydropeak’ release from a hydropower plant can be replicated on the experimental channels, which are 40 metres long and 6 metres wide. The channels are fed by an outflow from Lake Lunz, which provides nutrient poor water which is common in mountain stream environments.
Different temperatures of water can be taken from different outflows: one on the lake’s surface for warmer water during summer, and one at 10m depth for cooler water.
The effects of hydropeaking on the freshwater environment are being explored in these experiments by using three key freshwater groups: fish, represented by larvae and juveniles of the European grayling and brown trout; macroinvertebrates (or aquatic insects), which are collected from a nearby stream; and benthic algae that grows on the bottom of the stream bed.
The experiments seek to understand how far the fish and macroinvertebrates are forced out of their normal habitat by high flows (termed ‘drift’ by the researchers), and whether this causes them to become stranded (for example, on a gravel bar) as water levels quickly recede. The influence of gravel bar morphology, time of day and water temperature on this stranding risk will be investigated, along with rates of (re)colonisation of habitats by the different species after the hydropeak. The fish behaviour will be observed directly and through video analysis, and the fish will be safely released back into the wild after the experiments are finished.
Benthic algae are an important part of the food web in nutrient-poor mountain streams. These experiments will examine how the colonisation, photosynthesis rate and diversity of benthic algae communities is affected by daily hydropeaking. Researchers will also studying how rates of leaf decomposition – a process which releases nutrients into the water and encourage algal growth – vary with hydropeaking.
Caddis flies (Allogamus auricollis) on the stream bed. Image: Wolfram Graf
During a hydropeak event, there are changes not only to the water’s flow but also to its temperature. The experiments will examine how different species of macroinvertebrates are affected separately by each of the multiple stresses: temperature, flow speed and time of day. Understanding how different macroinvertebrates respond to different stresses will allow the researchers to identify indicator species, which can potentially be monitored in the future to assess the wider health of an ecosystem in response to a hydropeak.
The results of this exciting work will potentially allow for better informed environmental planning and policy decisions and impact assessments for hydropower developments on Alpine mountain streams. As with all the MARS experiments, we’ll keep you updated with the results.
Research team:
Lisa Schülting, Wolfram Graf, Elisabeth Bondar-Kunze, Thomas Hein, Stefan Auer, Bernhard Zeiringer, Stefan Schmutz and Rafaela Schinegger.
Contact: stefan.auer@boku.ac.at
Arctic char. Image: Jack Perks
Underwater filmmaking has a rich – but largely oceanic – history, from Austrian biologist Hans Hass’s pioneering work in the 1940s and Folco Quilici’s 1954 first full-length full-colour film Sesto Continente through to stunning modern footage such as in the BBC’s Blue Planet series and in Werner Herzog’s Encounters at the End of the World.
Jack Perks, an English natural history photographer and filmmaker, is attempting to bring freshwater environments into focus through his Beneath the Waterline project, which aims to document all of the UK’s freshwater fish on film. Keen to find out more, we spoke to Jack about his work and the challenges of filming freshwater life.
Freshwater Blog: Hello Jack, tell us a little bit about your work – how did you begin as a natural history photographer and filmmaker? What’s your approach to documenting the natural world?
Jack Perks: I started my professional career around 4 years ago when I left university with a degree in Marine and Natural History Photography and although I enjoy all aspects of British wildlife, it’s our fish that really caught my attention. With no specific NGOs for freshwater fish in the UK and very little photographic or video footage of them I decided it was about time to change that!
Tell us about the Beneath the Waterline project – what is it and where are you up to with the project work?
The project started in March 2014 and is funded mostly by donations from the public as well as a generous contribution from The Fisheries Society of the British Isles which enabled me to travel all over the UK to film. I had two goals for the project. One was to film as many British freshwater fish as possible, with an emphasis on native species, but also including non-natives and some sea fish that venture into river mouths.
The second goal was to create a film and short 1 – 3 min videos which are put on the project website to provide an online fish I.D guide. I will present the main film, which will deal with conservation issues like getting kids into nature, trying to get nature reserves to watch and appreciate the underwater world, and will feature species such as elvers (young eels) on the River Severn in Gloucester and the rare powan in Scotland. The film is nearing its end with one more presenting piece to be shot and a few more species to tick off.
Powan. Image: Jack Perks
It’s interesting that you raise the point that there’s no NGOs for UK freshwater fish (although there are a lot of broader freshwater ones) and little film footage: why do you think this is? Do you think we ignore freshwater life below the water’s surface? Is this something you’re trying to address with the Below the Waterline project?
One of the key points of the film is to raise awareness of our fish in general, particularly species most people haven’t heard of like spined loach, lamprey and Arctic char. I think the main reason for this lack of public awareness is “out of sight out of mind”, with so many species largely hidden below the water’s surface, most people don’t notice if they decline. I think that most people don’t even know whats lurking in the rivers, canals and lakes around them, so the film uses a mixture of close-up filming in tanks and shots of fish in their natural habitat. I’m hoping to show off our incredible diversity of freshwater fish species.
What technical challenges did the Below the Waterline project throw up? How did you go about finding the species to film (surely some must have been more difficult than others!), and what’s your working method for capturing them on film?
Timings were crucial and did cause me to miss a few species (like the river lamprey and shad) that I would very much like to have filmed. Most cyprinids breed in spring so it was a mad dash to try to capture as much breeding behaviour as possible, which meant that I did miss a few while trying to film others. Also I had to juggle the filming around commissions and filming for other groups while doing this project.
Being an angler helped me locate a lot of the fish, as did social media (here’s the project twitter account), with an army of people suggestion locations to go and film in places including London, Sheffield, Gloucester, Devon, Stirling, Cumbria and all over the East Midlands (my home region). I use a few filming methods including pole cams, underwater camera traps and snorkeling in rivers.
Barbel. Image: Jack Perks
One of the hardest fish to film was barbel. This was surprising, as I have quite a lot in my local area but the river water where they live was either too deep or murky to film. I had no success until a local angler told me about a suitable spot only 15 minute from my house and got them first time!
What has been your favourite fish to film, and why?
The barbel was certainly relieving to finally get but if I had to choose one, it would be the sea lamprey. I had people looking out for them on three different rivers and at the drop of a hat I’d travel to where one was spotted. I got a call from a river keeper on the Test (in Southern England) to tell about lampreys in the river, and so I got the first train to Southampton to film this primordial looking creature. It turned out that the conditions were ideal and plenty of sea lamprey were around spawning so I got lots of footage. They are incredible to watch as they move huge rocks to form a redd and move over each other in courtship.
The Below the Waterline film is coming out soon – can you tell us about it and where we can see it?
The premiere will be in Nottingham with showings in Bristol, London and more locations further north, and will also be available to buy on DVD and online. The hope is that the film will make people think a little more about freshwater fishes in different ways – they’re not just food for birds or a target to be hooked but an important part of our natural history and deserve to be celebrated as much as any other creature in the UK.
MARS Experiments: Extreme Flows in Nordic Rivers
The experimental flumes in action. Image: Susi Schneider
Last week we wrote about how the MARS project is carrying out seven long-term experiments across Europe to study how river and lake ecosystems respond to multiple stresses.
Today, we introduce the first of these experiments, ‘Extreme Flows in Nordic Rivers’. Many Nordic rivers have hydropower facilities along their length, which alters and constrains water flow. In particular, naturally occurring spates (or floods) are reduced in intensity, or prevented altogether. A lack of spates can mean that nutrient concentrations build up in the river, often causing potentially harmful algal blooms.
This experiment explores the question: what do spates do to Nordic river ecosystems? More specifically, it looks to understand the effect of spates on ecosystem structure – species composition and abundance of aquatic insects and algae – and functioning – the decomposition of leaf litter and insect grazing rate.
Building the flumes. Image: Susi Schneider
Four flumes, each four metres long, have been constructed at a site around an hour’s drive outside of Trondheim in northern Norway. They have been constructed as a result of a collaboration between MARS and ECOREG – a project funded by the Norwegian Research Council – and are being managed by researchers at NIVA (Susanne Schneider) and NINA (Zlatko Petrin). Water flow along the flumes is controlled by a set of gates, which allows for spate and normal flow conditions to be simulated.
In two flumes, normal flows – constrained by hydropower developments – will be simulated at all times. In the other two, normal flows will be simulated for a week, followed by three to four days of extreme flows, to simulate spate conditions.
On each flume are two mesh bags filled with alder (a common tree in the region) leaves. One bag has a large mesh, to allow aquatic insects to enter and graze on the leaves; whilst the other has a fine mesh to prevent this. There are also two ceramic tiles on the flumes, which provide an ideal habitat for algal growth. One tile has its edges covered in Vaseline to deter aquatic insects from grazing on any algae, whilst the other is left uncovered to allow for insects to graze on the algal growth.
Applying vaseline to the ceramic tile to encourage algal growth. Image: Susi Schneider.
One flume will be sampled for algal growth, leaf litter and aquatic insects each week. A Benthotorch is used to sample for algal growth on each ceramic tile. Decomposition rates for leaf litter will be calculated by drying and weighing the leaves in the mesh bags. Aquatic insect populations living in the leaf litter bags will be identified and weighed to give an indication of biomass. Finally, stable isotope analyses will be carried out on these insect populations to understand the relative importance of alder leaves and algal growth as different food sources.
In each case, these constant methods will be replicated across the two normal flow (or control) flumes, and the two spate flow flumes. This comparison will yield new insights about the effect of spate flows on insect and algae populations, leaf litter decomposition in Nordic rivers. This information could prove extremely valuable for environmental managers and policy makers attempting to understand the impact of hydropower schemes – in MARS terms a major source of stress – on the freshwater environment. We’ll keep you updated with the results, and introduce another experiment next week.
WWF Living Planet Report suggests 76% decline in freshwater species globally since 1970s
Global populations of freshwater mammals, reptiles, amphibians, birds and fish have declined by 76% since the 1970s, according to a new WWF report released today. The Living Planet Report measured the populations of 10,000 representative species across the world between 1970-2010, a method termed the Living Planet Index.
The results are startling and significant. Global populations of all wildlife – from land, freshwater and sea – have dropped by over half since 1970 – a dramatic fall in less than one human lifetime.
Freshwater species have fared particularly badly, a trend that the WWF report attributes to insufficient freshwater protected areas, habitat loss and fragmentation, pollution and the impact of invasive species (as also reported this year in a journal article by Ben Collen and colleagues in Global Ecology and Biogeography).
The report outlines how the global Ecological Footprint – the area (in hectares) required to supply the ecological goods and services we use – is growing, and is highest in North America and Europe. This growing consumption of the Earth’s natural resources places strain on global biodiversity.
China, India and the USA have the largest water footprint, in terms of water used for industrial and agricultural production, and contain 8 of the top 10 most populous basins experiencing almost year-round water scarcity. As a result of stresses such as water abstraction, dam construction and increasing climate change, the report states that more than 200 global river basins – home to some 2.67 billion people – already experience severe water scarcity for at least one month every year.
These reductions in natural freshwater flows and availability place stress on both human and wildlife populations. The report suggests that these levels of water scarcity are likely to get worse in the future under climate change, further population growth and the rising water footprint that tends to accompany growing affluence.
Marco Lambertini, Director General of WWF International said, “A range of indicators reflecting humanity’s heavy demand upon the planet shows that we are using nature’s gifts as if we had more than just one Earth at our disposal. By taking more from our ecosystems and natural processes than can be replenished, we are jeopardizing our future. Nature conservation and sustainable development go hand-in-hand. They are not only about preserving biodiversity and wild places, but just as much about safeguarding the future of humanity – our well-being, economy, food security and social stability – indeed, our very survival.”
The Living Planet index gives an indication of how global wildlife populations are faring over time. It uses data from 10,380 populations of over 3,038 vertebrate species (fishes, amphibians, reptiles, birds and mammals) studied by scientists, divided into land, sea and freshwater environments in both tropical and temperate environments. The Living Planet Index can then be used to observe whether individual species are increasing, declining or remaining constant, and then drawing wider trends for all species in different biogeographic realms (land, sea and freshwater).
You can read the full report online here and download the PDF summary here and tweet about the report using the hashtag #LPR2014.
Introducing the MARS river and lake experiments
NIVA experimental flumes for studying extreme flows in Nordic Rivers. Image: Susi Schneider
In previous posts, we have written about how freshwater ecosystems around the world are subject to multiple stresses on their health and diversity – for example, pollution, water abstraction and river fragmentation through dam building.
Researchers from the MARS project are interested in understanding the causes and impacts of these multiple stresses, and – crucially – how they make interact and multiply any potential negative impacts on the environment. Similarly, there is a need for research to simulate how multiple stresses might affect freshwaters under future climate change – how will changes to rainfall, temperature and storm frequency (amongst other factors) affect multiple stresses on freshwater ecosystems?
In order to explore some of these questions, MARS researchers have set up seven experimental sites across Europe as part of Work Package 3, where the effects of multiple stresses under different possible climate scenarios will be simulated. Three lake experiments will take place in the UK, Denmark and Germany using mesocosms. Four river experiments will take place in experimental flumes and channels in Portugal, Austria, Denmark and Norway.
Each experiment will focus on different aspects of how a freshwater ecosystem might respond to different stresses and changes to climate. By carrying out the river experiments in artificial channels and flumes, the MARS researchers can control and monitor all the factors affecting the experimental ecosystems, and closely monitor the results. Similarly, the mesocosms used in the lake experiment create closed conditions which closely simulate the natural environment, and again can be controlled and monitored. The experiment methods will be harmonised across all sites, which means that the data produced will give excellent coverage of different European environments under a range of potential climate conditions.
Over the coming months, we’ll write about each experiment in more depth:
- Low Flows in Nordic Rivers
- Extreme Flows in Nordic Rivers
- Peak Flows in Alpine Rivers
- Water Scarcity in Mediterranean Rivers
- UK Lake Mesocosm Experiments
The Northern Basins: modelling the Vansjø-Hobøl catchment
Lake Vansjø. Image: Raoul-Marie Couture
Last week we introduced MARS’s research on multiple stresses in the Vansjø-Hobøl catchment in Southern Norway. This week, we discuss the computer models that the Work Package 4 team will use to understand how rivers and lakes in the catchment respond to stress – largely nutrient pollution – both now and in the future.
Environmental models
Two computer models are being used by the MARS team to understand and predict how water quality in the catchment might respond to future environmental change, at both the catchment and lake scale. The data to run the MARS models in the Vansjø-Hobøl catchment comes from two monitoring programs: Bioforsk (river data) and NIVA (lake data).
Computer models are used to simulate the impact of different scenarios – for example, increased rainfall, air temperatures or fertiliser pollution – on freshwater ecosystems. Models are designed using observations taken in the field and laboratory on how different aspects of the environment respond to change and stress, and then use a complex set of calculations to simulate environments under a variety of different scenarios. Models are extremely important in providing guidance to environmental managers and policy makers in responding to environmental issues and predicting what impacts management is likely to have.
Catchment Model
The MARS team will use the INCA (‘Integrated Catchment’) model to understand the sources, distribution and impact of phosphorous through the Vansjø-Hobøl catchment. The INCA model tracks the flow and quality of water through the catchment, showing the dynamic, day-to-day fluctuations of these parameters in response to human-caused stresses such as agricultural pollution or sewage discharges. INCA can also be used to model the impact of long-term environmental and land-use changes – such as climate change and afforestation – on freshwaters in a catchment. It can model the dilution, natural decay and transformation (e.g. uptake by vegetation) of different chemicals – in MARS’s case for phosphorous, nitrogen and carbon – in water flows.
INCA then produces a range of visual representations of environmental responses to stress over time. The INCA model was developed by researchers at the University of Reading, the Swedish Agricultural University, the Finnish Environmental Institute and NIVA as part of several EU funded projects including Eurolimpacs, and others funded by UK government bodies such as NERC LOCAR.
As Paul Whitehead and colleagues demonstrate in a 2013 paper, INCA can be used to assess the cost-effectiveness of different schemes to manage and mitigate phosphorous pollution. Their INCA analysis of the River Thames in Southern England suggested that the most cost-effective management solution would be to encourage reductions in agricultural fertiliser use, alongside implementing improvements to sewage treatment processes.
River Hobøl Image: Reiseliv Indre Østfold
Lake Model
The dynamics and functioning of lakes in the Vansjø-Hobøl catchment will be modelled using the MyLake model developed by NIVA in Norway. As this 2007 paper by Tuomo Saloranta and Tom Andersen describes, MyLake is a ‘multi-year lake simulation model‘ that simulates the daily vertical distribution of lake water temperature, the evolution of seasonal lake ice and snow cover, sediment-water interactions and phosphorus-phytoplankton dynamics. These variables can be modelled through time by using known environmental factors such as the shape and depth of the lake (its ‘morphometry’), atmospheric conditions such as temperature, pressure and wind, and the amount of sediment and nutrients already in the lake (called ‘loading’ by ecologists).
As for the INCA catchment model, MARS’s focus is on phosphorous dynamics in the lakes and on the biological and physical processes controlling algal growth which can lead to harmful blooms. The MyLake model is particularly useful to policy makers as it allows for analyses to be made of the uncertainties in its predictions, and of the sensitivities of the model to the different input parameters.
Linking INCA and MyLake in MARS
In this 2014 paper, Raoul-Marie Couture and colleagues describe how the two models can be linked. Their key observation is that because the models run their analysis on a day-to-day basis using the same factors – phosphorus concentration and water quantity – they can be used in tandem to analyse both the lake and the catchment under the same scenarios, allowing for more thorough predictions of ecosystem responses to stress. Their paper’s conclusion is that both land use and climate change can increase the frequency of algal blooms, but that suitable management can overcome any detrimental effect of climate change if appropriately implemented.
Raoul explains how his collaborative MARS team will use the insights from this research to link the two models, “MARS is a motivating challenge because we have to use our most recent models for water quality in a totally new way. We will have to predict the response of biological indicators of water quality, consider the communication of results and uncertainty to stakeholders, and also say something on how the economic value of ecosystem services may change in response to environmental stresses. This forces me to reach out to biologists, social scientists and economists early on in the project.”
Raoul emphasised the novel, cross-disciplinary nature of this work. “This idea of linking models is not new, in fact most complex models are made of connected modules. However in MARS we will link models that would not normally be used together as one: including hydrological models, biological response models, and economic valuation models.”
Raoul added, “MARS researchers in Finland will use the exact same models (INCA and MyLake), but they have compiled them differently, and this is described in a 2014 paper by Maria Holmberg and colleagues. Their focus is more on carbon than phosphorus. In Estonia, they will also use INCA, but they have their own lake model adapted to the lake of interest, as described in a 2014 paper by Fabien Cremona and colleagues. These are three very recent developments in catchment-lake modelling.”
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