This week we feature two guest posts by scientists from MARS’ sister project SOLUTIONS. On Monday, we heard about the first SOLUTIONS General Assembly. Today, Werner Brack (UFZ Leipzig) and Ivana Teodorovic (University of Novi Sad) describe their research on chemical pollution on the River Danube in Serbia.
The River Danube is a truly international river which flows through ten countries across Central and Eastern Europe and has historically supported a wide range of freshwater species, yet is increasingly under pressure from pollution along its course. New research by the SOLUTIONS project on the Danube around Novi Sad in Serbia aims to find out how untreated wastewater pollution affects both the river ecosystem and drinking water supply from nearby underground aquifers.
Researchers from the Helmholtz Centre for Environmental Research UFZ and the Faculty of Sciences from the University of Novi Sad sampled three large volumes of river water from the Danube upstream and downstream of Novi Sad. The sampling team, led by Jörg Ahlheim from UFZ applied a new Large-Volume Solid-Phase-Extraction device to take samples of about 1000 litres of water 200m upstream and 7 km downstream of the biggest wastewater effluent outflows. Each of the sampling sites were fishing areas, where contamination is likely to affect the safe consumption of fish and thus human health. Local fishermen kindly supported the sampling campaign with their infrastructure and helped in words and deeds. Thanks a lot for that support.
The new water sampling device has been developed by the UFZ together with the small enterprise MAXX in Rangendingen, Germany and successfully tested and applied on the Joint Danube Survey 3 in September 2013. The device allows for on-site extraction of large volumes of river water for subsequent chemical and toxicological analysis. This technology avoids the transport and storage of large water volumes, which reduces logistic efforts and the risk of contamination. Only the smaller sample cartridges – the scientists call them ‘Sputniks’ – are transported to the lab for freeze-drying and subsequent extraction of chemical materials using solvents.
The extracts are awaited by a number of SOLUTIONS partners, who are tasked with developing a suite of effect-based tools – those which focus on the effects of mixed chemical ‘cocktails in freshwaters – which should help water agencies in Europe improve their monitoring of contamination and avoid unknown toxicants being overlooked. The samples from Novi Sad represent an interesting gradient of chemicals that will help to validate the tools.
To this end, the laboratories involved will investigate these samples for a large range of toxicological endpoints relevant for human and ecosystem health, such as toxicity to algae and fish embryos, mutagenicity (i.e. the process of mutation), adaptive stress responses and multiple hormone-like effects. At the same time the samples will be chemically screened for several hundred water contaminants to complete the picture on contamination.
Arslan Kamal, a PhD student at the UFZ, and Sven Seidensticker from the RWTH Aachen plan to go one decisive step further, supported by experts on effect-based tools from SOLUTIONS. Combining biological and chemical tools, Kamal and Seidensticker want to stepwise reduce (i.e. through a gradual progression) the chemical complexity of the samples and identify those chemicals causing effects in bioassays (lab-based experiments to study the effect of chemicals on cells or tissues).
This approach is called effect-directed analysis and is designed to establish cause-effect relationships between chemical pollution and ecosystem response. Identification of particularly problematic compounds in aquatic environments is one of the key tasks for SOLUTIONS. All the information collected in this first campaign of sampling and analysis will provide the basis for in-depth ecological studies in 2015, when it is planned to also investigate fish and invertebrates in the river for adverse effects.
In order to inform the local population on SOLUTIONS and the goals of the project sampling campaign, Serbian TV filmed the sampling and interviewed Prof. Ivana Teodorovic from Faculty of Sciences and Dr. Werner Brack (UFZ), the coordinator of SOLUTIONS (video above). In a meeting with Serbian stakeholders both scientists explained the concepts of the project to representatives of national, provincial and city authorities for science and environment as well as water management companies.
For them the approach is of twofold interest. They appreciate the participation and active scientific role of a Serbian group in the leading European project on emerging pollutants. But they are also interested in the results on the water resources they want to protect particularly against the background of a planned wastewater treatment plant, which still needs funding to be realised. The SOLUTIONS investigations before the realisation of this plan will be a helpful basis to evaluate its success.
This week, we feature two guest posts from scientists at MARS’ sister project SOLUTIONS. In this piece, Thomas-Benjamin Seiler (RWTH Aachen), David Lopez-Herraez and Werner Brack (UFZ Leipzig) reflect on the first SOLUTIONS General Assembly, which took place in October 2014.
“Are the fish from European rivers safe to eat?” It’s a simple but crucial question that Sibylle Ermler, environmental researcher at Brunel University in the UK, seeks to answer as a member of the SOLUTIONS ‘family’. The first SOLUTIONS general assembly brought together questions like this from researchers across Europe, and created a space to collaborate and share ideas and potential solutions.
SOLUTIONS (project factsheet pdf) is the project name of the collaborative endeavour entitled “Solutions for present and future emerging pollutants in land and water resources management” for the 7th Framework Programme for Research and Technological Development of the European Commission under the coordination of Werner Brack, Helmholtz Centre for Environmental Research, UFZ, Germany. With funding budget of nearly 12 million Euro and the involvement of organisations from 17 European countries, SOLUTIONS is a major effort in European environmental research to ensure future ecological quality of our freshwater bodies as required by the EU Water Framework Directive (WFD).
Solutions General Assembly
From 13th to 16th October 2014, the SOLUTIONS consortium – consisting of a total of 39 partner institutions from academia, official authorities and business, and more than 100 scientists and professionals at all different levels of education – held their first annual general assembly. This gathering event was hosted by Jos van Gils and his group from the Dutch partner Deltares at their headquarters in the city of Delft, and had many unusual and productive features.
Attendees were challenged by a wealth of diverse communication and discussion formats including: conventional meetings focusing on sub-project and work-package tasks and oral presentations on SOLUTIONS’ progress; thematic workshops on risk assessment and on innovative regulation of chemicals promoting the dialog among participants using a fishbowl approach; and self-organised conversations on the project’s overarching issues using an open space methodology to address the most urgent questions. The SOLUTIONS general assembly even had its own Science Slam contest.
One highlight for sure was the mini-conference reporting on SOLUTIONS progress, featuring 30 5-minute presentations on all kind of different work conducted within the first year. Outcomes clearly showed that the project’s start has been very proficient. Positive feedback from our stakeholders promises that SOLUTIONS is likely to have major impacts on the way freshwater management will be done in the future in Europe and maybe even worldwide.
Solutions-orientated and effects-based approaches
The general assembly addressed all major elements of a solutions-oriented approach – i.e. one that investigates the ‘cocktail’ of dissolved chemicals present in water – in prioritising and assessing emerging pollutants in the water cycle through monitoring, modelling and abatement. Monitoring-based approaches in SOLUTIONS have a strong focus on effect-based tools and multi- and non-target chemical analysis. Both are applied for screening and in-depth site-specific evaluation of freshwater contaminants.
Chemical monitoring for freshwaters is often focused on regulated substances which are known to pose a threat to aquatic ecosystems. However, because there are so many new and novel chemicals entering freshwaters, the effect-based approach seeks to understand the ecological effects of the mixed chemical ‘cocktail’ present in water, and then to potentially link these effects to suitable management solutions (for more, see this European Commission report pdf).
Sonja Kaišarević of University of Novi Sad in Serbia wants to use such tools “to identify the culprits that are impacting environmental health.” She feels proud to be part of SOLUTIONS. The same holds true for Fangxing Yang, who is a postdoc at the UFZ in Leipzig, Germany. His task is to work on the “effect-directed analysis (EDA) in fish.” This approach aims to use biomarkers (i.e. indicators of biological state) and other effect-based tools together with in-depth chemical analysis for an effect-directed analysis of emerging freshwater pollutants in fish. Fangxing hopes to develop this effect-directed analysis approach as a tool to better protect the environment and human health. “I am feeling very comfortable within SOLUTIONS“, he says.
Joining up the pathways of chemical pollution
Small breakout groups worked on issues raised during plenary discussions or suggested by participants. One group on so-called Adverse Outcome Pathways (AOPs) tried to better outline how this approach can, and will, be implemented into the SOLUTIONS framework. The AOP approach aims to link effects on all different biological levels – from (sub)cellular mechanisms such as enzyme inhibition or DNA damage to impact on organs – with the eventually observed adverse effect of a contamination. The transfer from the effect on the individual – e.g. a single fish – to the population and the ecosystem was of special interest for the group. A key challenge arising from the discussion was that scientists have to define and agree on what an adverse effect of pollution actually is.
Predicting and managing chemical pollution
While monitoring is a key approach for the assessment of contamination today, it requires support from predictive approaches to identify chemicals that may become a problem in future. Emission, transport and fate modelling tries to draw insights out of the wealth of data from chemical regulation. Claudia Lindim from Stockholm University provided an impressive example of simulating PFOS (a man-made chemical used as a fabric stain repellent) concentrations in the Danube river basin.
However, SOLUTIONS does cover more than monitoring and modelling of contamination and risks only. For Annemarie van Wezel from the Dutch KWR Watercycle Research Institute, a key question is: “Where and how to spend limited resources for pollution abatement in a way to improve valuable natural areas and drinking water resources?” For Annemarie, combined chemical monitoring and modelling helped to identify the highest priority locations for an upgrade of wastewater treatment in the Netherlands.
Bringing all these different aspects together and establishing integrated and consistent roadmaps towards the anticipated products of SOLUTIONS was a big task during this general assembly. The enormous enthusiasm and involvement of all partners and numerous discussions from bilateral to workshop format helped to bring the project a big step forward.
The importance of young and early-career scientists
Numerous young and early-career scientists played an important role in the general assembly. They took the opportunity to present in different formats, to understand the concepts and to meet many of those scientists they knew from academic literature. For PhD students Ying Shao and Björn Deutschmann from RWTH Aachen University in Germany, the general assembly was especially useful to better understand the high complexity of the project, and to find their role within the consortium.
“I am overwhelmed”, Ying says, “but desperate to learn.” Her task in SOLUTIONS is to identify pollution hot spots and elucidate modes-of-action of freshwater pollutants using small-scale in vitro bioassays (i.e. using tissues or cells in the lab to study the effect of pollutants). Her work is supported by a four-year PhD fellowship from the China Science Council (CSC). After finishing her thesis Ying wants to return to China and contribute to environmental quality at home. Björn feels quite “challenged.” He works on a larger scale than Ying, investigating certain biomarkers in feral and lab-exposed fish. Both students want to help to make a step forward in Adverse Outcome Pathway definition and bring the concept to the organismal level.
The Delft meeting helped both young researchers to better shape their theses. They used the fantastic networking opportunities to establish valuable contacts with other members of the SOLUTIONS family. With a consortium spreading all over Europe, and reaching to China, Brazil and Australia, proper communication is a real challenge, even nowadays with all different kind of digital conversation channels. Meeting up face-to-face is still the most efficient way to exchange ideas, discuss problems, and make decisions. In these terms the general assembly was a huge success.
Science slam and a singing professor: a diverse and supportive project
The SOLUTIONS science slam on Wednesday evening proved that internal project communication does not have to be a dry, rather serious activity. Five slammers brought on stage high creativity in presenting their science to colleagues. The science slam was carried out without slideshow presentations and involved such diverse media as movie clips, live imaging and custom-made cardboard chemical analysis equipment. The winning contribution, however, borrowed from hard rock pioneers Deep Purple. Dirk Bunke of Öko-Institut e.V., Freiburg, Germany, got the whole audience to sing along “Smoke on the water – pollutants of tomorrow.”
A singing professor, highly enthusiastic PhD students, experts on AOPs, bioassays, chemical analysis, statistics and modelling; laboratories equipped with state-of-the-art scientific devices; and an unlimited amount of creativity to find the best solutions: the Delft general assembly showed that the real strength of the project lies in a consortium so broad and diverse that virtually any research problem of any colleague can be solved by someone from the project. This unique capability of the SOLUTIONS family is good news for environmental quality of European freshwater bodies and promises very valuable results and developments.
Bringing together projects and collaborators from across the world
Armelle Herbert could be one of the people to benefit from the project outcomes. She is a representative of Veolia Environnement Recherche & Innovation France, and a member of the SOLUTIONS stakeholder board, a panel of decision-makers and end-users involved throughout the life of the project. She liked the innovative approach of the general assembly, its interactivity, and the ease with which she could start conversations with the participants. She enjoyed that it was no ‘classical’ scientific conference, and the mini-conference was a particularly refreshing experience for her. For the first time, our Stakeholder Board members from the United States Environmental Protection Agency, Rob Burgess, and Environment Canada, Mark Hewitt, joined a SOLUTIONS meeting. They identified plenty of common interests, problems to solve and approaches to take and presented the North American perspective on emerging pollutants in the Stakeholder Board meeting.
The general assembly was also very happy to host Sebastian Birk representing the partner project MARS and Damià Barceló as the coordinator of GlobAqua. Close collaboration between the projects has been identified as a key step to increase the scientific impact towards better understanding and protecting aquatic ecosystems against multiple stressors including emerging pollutants. In outstanding presentations, SOLUTIONS participants learnt about the concepts and approaches of both partner projects.
SOLUTIONS: a great opportunity
“In the beginning I was overwhelmed by the complexity”, Knut Erik Tollefsen of NIVA, Norway, suggests. Knut Erik is the leader of the whole working package on effect-based methods, and had a significant share in writing the entire SOLUTIONS proposal. But still for him the project is a challenge, showing the large effort the scientists put into their work. “Then I was very positively surprised by the assembly of competence within the project consortium”, he continues, which makes him “confident that we will achieve what we aim for.” Andreas Focks of ALTERRA in The Netherlands adds, “this project is a great opportunity to achieve things that were not achievable before.” Certainly for most participants the general assembly in Delft brought the very same feeling.
The 17th IWA International Conference on Diffuse Pollution and Eutrophication has been announced to take place at the Best Western Premier Hotel MOA Berlin, Berlin from 13 to 18th September 2015. The abstract submission is open here.
Organised by the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB) and International Water Association (IWA) the conference aims to:
“The complexity and variety of processes, substances as well as interests and needs of stakeholder and users turns basin and water quality management into a challenging task and unites scientists, economists, engineers, lawyers, policy specialists and stakeholders to develop new approaches and solutions to protect natural resources.
The DIPCON 2015 continuous a 20 year tradition of conferences on international exchange of knowledge and technology among established and young specialists from developed and developing countries. The conference’s goal is to bridge between basic and applied science, technical solutions and the knowledge transfer into basin management. Here, following a holistic perspective, diffuse point source pollution is considered likewise. The conference provides a platform for contemporary and high-quality research and technical solutions as well as for international networking, establishing and intensifying cooperation between science, administration and industry.”
The conference programme will include sessions on pollutants and sources of diffuse pollution in surface and ground waters; diffuse pollution from agriculture and forestry, as well as from urban areas and mining; diffuse pollution under global changes; nutrients and eutrophication issues; surface waters under multiple stress; modelling and monitoring; policies, regulations and education to control diffuse pollution and integrated watershed management towards controlling diffuse pollution.
Delegates will also be offered the opportunity to take part in a conference dinner and to attend a field excursion.
Follow the Conference website for updates.
There are currently around 3,700 major new hydropower dam projects planned or under construction across the world, many of them in developing countries which lack widespread, reliable and affordable electricity supplies. However, many of these same countries support biodiverse and relatively ‘natural’ large river systems, which raises questions of how to balance the potential ‘green’ energy gains from hydropower projects with the potential harm – barriers to fish migration, siltation, habitat change amongst others – they can cause to river ecosystems.
A new study ‘A global boom in hydropower dam construction‘, has been carried out by Professor Christiane Zarfl from the University of Copenhagen and colleagues at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) in Berlin, including BioFresh head Klement Tockner. The research team compiled data on future major hydropower projects to predict how much energy would potentially be produced if all projects were completed; and the potential impacts they would have on currently free-flowing river ecosystems.
The team found that despite a global ‘boom’ in hydropower developments, the extra electricity production “will not close the energy gap“, because energy demands will increase, due to growing human populations globally. So despite the growth in global hydropower capacity – if all 3,700 dam projects were completed, the capacity would double to 1700 gigawatts (GW) within the next 20 years – the study predicts that the proportional hydropower contribution to overall energy production would barely alter (16% in 2011, 18% in 2040). In short, the ‘boom’ in hydropower projects across the world – and their negative impacts on river ecosystems – will only keep pace with global energy demands, as opposed to providing a higher share of ‘green’ energy to overall supply.
The study shows the geographical spread of where new hydropower projects are planned, and so provides a basis for understanding where and how the various trade-offs and conflicts between energy production, freshwater biodiversity and human livelihoods are likely to take place in the future. The maps below show: (1) the distribution of future hydropower projects, under construction (blue dots) or planned (red dots); and (2) the number of hydropower projects for each major river basin. The maps show how the majority of hydropower construction will take place in developing countries and emerging economies, particularly along the Amazon basin in Brazil, the Ganges–Brahmaputra basin in India and Nepal, and the Yangtze basin in China.
Speaking to ECOS Magazine, Professor Zarfl said, “Hydropower is an integrated part of transitioning to renewable energy and currently the largest contributor of renewable electricity. However, it is vital that hydropower dams do not create a new problem for the biodiversity in the world’s freshwater systems, due to fragmentation and the expected changes in the flow and sediment regime. That is why we have compiled available data on future expected hydropower dams – to form a key foundation for evaluating where and how to build the dams and how to operate them sustainably.”
The study estimates that 25 of the 120 large river systems currently classified as ‘free-ﬂowing’ would lose that status, as dam construction fragments and modifies their courses. It suggests that “Worldwide, the number of remaining free-ﬂowing large river systems will thus decrease by about 21 percent” – a decrease which is likely to be most prominent on South American rivers, which are some of the world’s most unique and diverse freshwater ecosystems.
The IUCN Freshwater Fish Specialist Group states that South America is the most diverse continent for freshwater fish species, globally, with an estimated 4,000 species (and roughly 100 new species found each year). The Amazon, Mekong, and Congo basins, which will be heavily impacted by future hydropower dams, jointly contain 18 % of the global freshwater fish diversity, and the Balkans – a hot spot for future hydropower development – are an important region for freshwater biodiversity in Europe, as described by a recent IUCN report.
Freshwaters are already amongst the most threatened ecosystems in the world. Hydropower developments can have negative effects on freshwater species in a number of ways – blocking migration routes, changing river flows and habitat, and dropping loads of fine sediment in areas where the river flow is slowed, potentially causing eutrophication and covering fish breeding sites. Biodiversity loss as a result of hydropower projects has potentially negative knock-on effects for communities around rivers which rely on fishing for food and freshwater for drinking, washing and sanitation.
Despite being a low-carbon, renewable energy source, hydropower can significantly alter and degrade the rivers where it is implemented. So, what is the solution to growing global energy demands? Professor Zarfl and colleagues state that, “Even if the entire technically feasible hydropower potential will be exploited, which would correspond to a dam construction boom almost five times that currently estimated, hydropower would contribute less than half of the global electricity demand projected until 2040.”
Given this inability to keep up with demand, and the related environmental costs, is hydropower the most suitable response to global energy needs? On average, life-cycle greenhouse gas emissions from hydroelectricity are more than 30 times lower than that of coal – potentially providing a key tool in mitigating climate change. However, how can we reconcile the potential climate benefits of hydropower with the potential harm it does to freshwater biodiversity?
The authors suggest that one solution might be to concentrate new hydropower developments on river basins that have existing hydropower projects, and are fragmented already – a new and perhaps pragmatic take on the old conservationists’ mantra of ‘preserve the best, restore the rest’. For example, hydropower projects on the Rufiji River in Tanzinia – the last remaining large free-flowing river network in East Africa – might be moved to the Nile and Zambezi Rivers, which are already heavily fragmented today. Whether this approach can account for spatial variation in energy needs, economic investment and political will is another matter.
The database of future major hydropower projects compiled by Professor Zarfl and colleagues provides a comprehensive new resource for conservationists, environmental planners and policy makers to help guide how and where hydropower developments are planned in the future. However, it remains to be seen whether the growing global demand for new hydropower supply can be reconciled with the threats developments pose to freshwater ecosystems in the future.
The 14th International Symposium on Aquatic Plants has been announced to take place at the Playfair Library in Old College, Edinburgh between 14-18th September 2015. Registration and abstract submission is open here.
Organised by MARS colleagues at the Centre for Ecology and Hydrology in Edinburgh, the conference aims to: “promote debate on all issues relating to the science and management of aquatic vegetation. Interest in aquatic plants has been growing and diversifying and to reflect this there will be a wide Scientific Programme which will appeal to scientists and managers.”
The conference programme will include sessions on Ecotoxicology, Trophic Interactions in Macrophyte Beds, The Future of Invasive Species Management, Community Responses to Environmental Change in Space and Time, Aquatic Plants and Physical Processes, Restoration, Aquatic Plant Monitoring, Ecological Stoichiometry and Nutrient Cycling, Vegetation & Dams, and Fundamental Science.
Delegates will also be offered to opportunity to take part in a conference dinner and ceilidh at Surgeon’s Hall, and to attend a field excursion to Loch Leven to see an excellent example of successful lake restoration.
Key Biodiversity Areas: new IUCN report finds that Mediterranean freshwater ecosystems are inadequately protected
Three-quarters of the Mediterranean region’s most valuable areas for freshwater biodiversity lie outside of protected areas, leaving some of the most area’s most important and diverse freshwater ecosystems vulnerable to human threats. This is the key finding of a new IUCN assessment reported to the recent IUCN World Parks Congress in Sydney, Australia.
The report suggests that at least 167 sites in the Mediterranean Basin –covering an area of 302,557 km2 – qualify as freshwater Key Biodiversity Areas (KBAs) . Key Biodiversity Areas are an IUCN designation of the most important sites for biodiversity conservation worldwide, particularly important in maintaining species populations. They are assessed globally using a standardised criteria based on how vulnerable and irreplaceable the populations of plants and animals they contain are.
The above video gives an introduction to freshwater Key Biodiversity Areas, and the new online BioFresh portal for accessing information on them.
Freshwater biodiversity is poorly accounted for in the global protected area network. The new IUCN study provides crucial information on critical sites for freshwater biodiversity, and sets the foundation for a new protected area network in the Mediterranean Basin – a region rich in diverse and threatened freshwater life.
This work was undertaken in partnership with the BioFresh project. Two BioFresh partners outlined the new study’s value:
“Through this project we are putting freshwater biodiversity on the map in a region of the world where pressures on inland wetlands are rapidly driving species to the edge of extinction – a number have already been lost. The next crucial step is to build widespread awareness of these important sites and to stimulate targeted conservation on the ground” said Will Darwall Manager of the IUCN Freshwater Biodiversity Unit and project coordinator.
“KBAs are fragile freshwater ecosystems which must be properly managed as part of Integrated River Basin Management planning accounting for the wide range of uses of water across sectors” commented Jörg Freyhof, European chair of the IUCN/WI Freshwater Fish Specialist Group and co-author of the report.
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.
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.
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.
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.