Meet the MARS team: a selection of audio snapshots
Snowy mountain cabins above Fulda. Image: MARS Project
At the recent MARS meeting in Fulda we spoke to a number of project scientists to ask them about their work and their part in the project.
We recorded short audio ‘snapshots’ of each conversation to give a flavour of some of the themes of the week, and the people behind MARS. The results are embedded below to stream and download – enjoy.
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The science and policy of multiple stressors: four reflections from the MARS Mid-Term Meeting
Daniel Hering welcoming attendees at the MARS mid-term meeting in Fulda. Image: MARS
Last week, the MARS project held its mid-term meeting in Fulda, Germany. The meeting brought together project scientists, water managers and policy makers to discuss ongoing research into freshwater multiple stressors.
Below are four audio reflections on the meeting.
The first is from project leader Daniel Hering, who gives an overview of the progress MARS has made on the science and policy of multiple stressors.
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Next, Bas van der Wal of water management agency STOWA in the Netherlands tells us about his golden rules for translating freshwater science into policy and management using ‘ecological key factors’.
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We speak to Rolf Altenburger from the Helmholtz Centre for Enviromental Research (UFZ) in Leipzig, Germany about freshwater pollution and the SOLUTIONS project.
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Finally, Anne Lyche Solheim from NIVA in Norway tells us about the challenges of researching multiple stressors and creating dialogue with water managers and policy makers.
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Kathleen Carpenter: the mother of freshwater ecology
Cwmystwyth a metal mining area near Aberystwyth in Wales. The River Ystwyth to the left of the picture was heavily polluted by the mines. Image: W. L. Kovach
In this guest post for International Women’s Day, Dr. Catherine Duigan draws from her research on Dr. Kathleen Carpenter (1891-1970), the ‘mother’ of freshwater ecology, to suggest insights and wisdom that Carpenter might offer to new generations of freshwater scientists.
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Image of Kathleen Carpenter supplied by Piotr F Piesiewicz
I am an ecologist born in the late 1800s, and I wrote the first British freshwater ecology textbook, Life in Inland Waters (1928). Julian Huxley, the textbook series editor, recognised that the ‘Cinderella charms’ of freshwater biology were at the time being ‘eclipsed by those of her elder and more ample sister, Marine Biology’. My textbook was developed to support undergraduate education in the field and redress the balance.
Fortunately, I was also born at a time when the rights of women were starting to be acknowledged. I attended and worked at universities in Europe and the US which pioneered the education of women, including the University of London, University College of Wales at Aberystwyth and Radcliffe College in Massachusetts.
When I arrived at Aberystwyth in 1911, some of the local river systems were devoid of life. My research linked the lack of invertebrates in these rivers to metal mining activity and demonstrated the way that fish gills were damaged by pollution, which often led to suffocation. My textbook described the different natural zones in rivers and lakes, and recognised the adaptations of different biota in aquatic ecosystems. I also recorded glacial relict species in British streams. Students at Aberystwyth to this day continue to discover my papers as part of literature reviews and the river research continues.
What would be my advice to the next generation of female freshwater ecologists?
Do something you love and be passionate about it
Passion helps to inspire the next generation. I gained a huge amount of aesthetic and scientific pleasure in describing and observing the organisms in rivers and lakes. In the preface to my textbook I talk about “a world of infinite beauty, infinite variety, infinite charm”. Showing passion makes people take notice and realise that some things are special.
Work hard at communicating your research
I was a communicator from the early days of my career as an assistant lecturer at Aberystwyth University. The textbook provided a story which lasted several decades and was supplemented by a series of scientific papers in a range of journals. I was also a regular contributor to conferences in Britain and abroad. It was amusing to generate newspaper headlines about ‘cannibal salmon’ after presenting a dietary study and referring to a spent male which had potentially consumed his own offspring. Today I would be using social media! #freshwaters #pollution #Faberystwyth!
Play a part in your professional learned societies
I was a member of several scientific societies, including the British Association for the Advancement in Science, Sigma Xi and the British Ecological Society. Scientific meetings provide incentives to produce high quality work and opportunities to travel and develop a professional network. Build your confidence by talking to the leaders in your field.
Travel and gain experience
In the early part of the 1900s freshwater science was developing in Europe and North America. I sailed across the Atlantic several times, travelling alone with up to $100 dollars in my pocket. One particularly memorable voyage to a scientific conference in Toronto had many eminent male scientists on board. I lived, taught and undertook research in British and American academic communities.
Take time to encourage other women.
I would be delighted to be considered a role model for young women scientists. In the US I was a member of the Delta Epsilon Sigma Society which was founded to provide women with an environment where they could network and interact with peers in informal and powerful ways that male scientists could. I still remember the tea party at Illinois State University before the meeting of the American Association of University Women in October 1928 where I contributed as a guest of honour to the discussion on British Universities.
Be generous to your students (and staff), they will reward you too.
A good relationship between teacher and student cultivates a common understanding and stimulates learning. One of my recorded awards was to have been elected to the Honor Society by the undergraduates of Washington College. The production of a textbook early in my career was a gift to future students. Take the time to talk and share knowledge.
Interdisciplinary research is vital for advancing our understanding of the world
In Life in Inland Waters I made the case for interdisciplinary research combining approaches from chemistry and biology to assess water quality. I would like to be contributing to current research into the links between the natural environment and human well-being, because I believed time spent by city workers on the riverbank was good for health and a quiet mind.
Speak more than one language
In the early decades of the 1900s freshwater science was dominated by continental European studies. Fortunately I was well placed to interpret them and present them to a wider audience because my father was German, and I had a working knowledge of French. Knowing more than one language increases your accessibility to information, especially indigenous knowledge, and can open up collaborative opportunities. Sign up for that class in Spanish or Welsh!
Demonstrate the practical relevance of your work
Nature is important in its own right – there to be enjoyed and protected – but today I appreciate that the final chapter in Life in Inland Waters reads like an early attempt to form the concept of ecosystem services. I thought it important to demonstrate the wider socio-economic context of my work: from the financial value of salmon sold at Billingsgate market in London to the human health risks of dirty water. My research informed the remedial efforts of a local River Pollution Committee. Perhaps this can be considered an early example of research having science-policy impact.
Wear sensible clothes when you do fieldwork and be safe
Can you contemplate the prospect of sampling a river whilst wearing a long skirt?! Fortunately for me, following the First World War women were able to adopt more practical, working clothes, including trousers. I can endorse research in the history of science which suggests that the development of sports clothing helped to make fieldwork socially acceptable for women ecologists. Working in an aquatic environment comes with risks, and you need to embrace health and safety requirements. Be sensible.
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Dr. Catherine Duigan was educated at University College Dublin where she did a Ph.D on zooplankton in Irish lakes. Her international research background has included working in the USA, France, and Africa. She did post-doctoral research at Aberystwyth University and was the only woman to take part in two expeditions to the High Atlas Mountains in Morocco.
Catherine then went on to follow in the footsteps of Kathleen Carpenter with a professional interest in freshwater ecology in Wales, including writing and co-editing The Rivers of Wales book. She is currently leading a group of technical specialists covering aquatic and terrestrial environments at Natural Resources Wales in Bangor. As an honorary lecturer at Bangor University she contributes to teaching modules on freshwater ecology. She is also a STEM Ambassador.
Catherine considers bringing attention to Kathleen Carpenter’s history a very welcome obligation. Women scientists need to tell each other’s stories.
River Torridge in Devon, a sample site for mayflies in the study. Image: alexwhite | Flickr
Polluted rivers with low oxygen levels are more susceptible to the harmful effects of climate change, according to a new study co-authored by MARS scientist Professor Steve Ormerod.
Researchers from Cardiff University and Radboud University in the Netherlands led by Wilco Verberk used laboratory studies and over 42,000 samples from UK rivers to show that two common mayfly species are less able to tolerate rising water temperatures in polluted rivers with low oxygen levels. The breakdown of organic pollutants such as sewage and farm run-off uses oxygen, meaning that polluted waterways often suffer severe drops in dissolved oxygen levels.
The study, published in Global Change Biology (open access), adds to the growing evidence on the influence of multiple stressors in shaping how freshwater ecosystems are likely to respond to climate change. Specifically, it suggests that reductions in water pollution may help increase the resilience of freshwater biodiversity to the effects of future climate change.
“Cool water insects like many mayflies are in triple jeopardy in warmer, polluted waters,” explains Professor Ormerod. “First, at higher temperatures, water can hold less oxygen. Secondly, insects need more oxygen to keep pace with their needs as temperatures increase. Thirdly, oxygen is used in the breakdown of organic pollution, with this effect occurring most rapidly in warmer waters. These three effects mean that warm polluted waters are the worst combination.”
Blue-winged olive (Serratella ignita) Image: Wikipedia
In laboratory studies, the team found that mayflies such as the green drake (Ephemera danica) and the blue-winged olive (Serratella ignita) were able to survive temperatures 3-5 °C higher where oxygen levels were high, compared to where they were depleted. Hypoxia – or severe oxygen depletion – lowered lethal water temperature limits by roughly 5.5 °C and 8.2 °C for the green drake and blue-winged olive respectively. Mayflies were used as bioindicators in the study as they are common and ecologically important features of many river and stream ecosystems.
Analysis of long-term field study data provided support for these laboratory findings, showing that mayfly populations were significantly reduced in poorly oxygenated stream sites, and that these reductions were particularly pronounced under warm water conditions. In short, low oxygen levels reduced the optimum stream temperature for mayfly populations, and threatened their abundance. The team used data provided by the Environment Agency and Natural Resources Wales collected using kick samples from 2632 sites across England and Wales between 1989 and 2008.
Green drake (Ephemera danica). Image: Wikipedia
In bringing together field and laboratory studies as a means of assessing how reductions in pollution may help to adapt river ecosystems to climate change, the study is highly innovative. The broad similarities in findings between the field and laboratory studies suggests that low oxygen levels not only impair mayfly survival at extremes of temperature, but can also restrict their abundance at temperatures well below lethal limits.
Improving water oxygenation through management of pollution could thus provide a key element in strategies to adapt Britain’s rivers and streams to climate change, potentially increasing ecosystem resilience to rising water temperatures in the future.
Co-author Dr Isabelle Durance, Director of Cardiff University’s new Water Research Institute states, “Our work presents real hope in the fight against climate change. We need to find ways to reduce the future effects of warming, and our data show how regulating and reducing pollution offers real benefit.”
Remote alpine lakes affected by nitrogen from agriculture transported across vast distances in the atmosphere
White Miller Lake in the Uinta Mountains. Image: Pierce Martin | Flickr
Remote mountain lakes in Utah, USA receive significant amounts of nutrients transported in the atmosphere from human activities many miles away, according to a new study. High alpine lakes are generally nutrient poor, and so this atmospheric arrival of nutrients – largely originating from nitrate and ammonium based fertilisers used in agriculture – has the potential to significantly alter the health and functioning of their ecosystems.
The study, led by Beth Hundey from The University of Western Ontario and recently published in Nature Communications (open access), suggests that for alpine lake ecosystems, “even modest increases in nitrogen deposition can have significant effects including eutrophication, acidification and the reduction of biodiversity.”
In order to protect these remote ecosystems, which often provide water resources for nearby lowlands and hotspots for rare and endemic biodiversity, it is important to identify the sources of nitrogen that reach them.
Reactive nitrogen (given the chemical symbol Nr) is the name given to all forms of biologically available nitrogen, including inorganic forms such as ammonia, ammonium, nitrogen oxide and nitrates; and organic compounds such as urea and nucleic acids. Reactive nitrogen is added to the environment naturally by lightning strikes and nitrogen fixation.
However, human activities such as synthetic fertiliser production and fossil fuel contributions have doubled levels of reactive nitrogen in the Earth’s nitrogen cycle. The emissions from such nitrogen-producing activities may be transported and deposited hundreds, even thousands, of miles from their source.
Mirror Lake in the Uinta Mountains. Image: Bryant Olsen | Flickr
The team analysed three stable isotopes (Δ17O, δ18O and δ15N) sampled in water from lakes in the Uinta Mountains in northeastern Utah, USA. This analysis allowed the team to determine where the nitrates found in the lakes – which are remote, with little direct human impact – originate from and how they were transported. For example, the isotope samples allowed the team to differentiate between nitrates originating from fossil fuel burning, biomass burning and lightning that is oxidised in the atmosphere; and those which are oxidised in land and water ecosystems.
Their results show that at least 70% of the total nitrate inputs into the Uinta Mountain lakes originate from the atmosphere. The majority of the nitrates arriving into the lakes are the result of agricultural activities, specifically the use of nitrate and ammonium fertilisers. The research team suggest that, “similarities in nitrate isotope compositions between Uinta Mountain lakes and lakes throughout the US Rocky Mountains suggest that these findings apply to other mountain regions in western North America.”
These findings are significant because they highlight how nitrate-caused ecological stress in mountain lakes may be the result of from multiple sources of nitrogen located many miles from the affected ecosystems. In short, human activities such as intensive agriculture have the potential to negatively impact even the most seemingly remote or ‘wild’ places.
For environmental managers and policy makers seeking to conserve these ecosystems, the study suggests that the geographical range of potential nitrate sources must be widened if nitrate levels are to be managed and their effects mitigated. Here, local ecological stresses are inextricably tied to wider-scale human activities. As such managing the emission and transportation of nitrates across vast distance is likely to pose ever more complex challenges for environmental policy and conservation.
Functional redundancy and how river ecosystems respond to stress
A well preserved section of the Segura River in Murcia, Spain, showing a riparian area dominated by black poplar, ashes and willows.
This week we have a guest post written by Daniel Bruno and Cayetano Gutiérrez-Cánovas on their new Journal of Applied Ecology paper which examines the potential of using the functional redundancy concept to assess how river ecosystems respond to stress.
Daniel is a researcher at the University of Murcia in Spain. His work explores river conservation and restoration, riparian ecology and the use of indicators to assess ecological status. Tano is a research associate at the University of Cardiff in Wales, whose work in the MARS project analyses how aquatic ecosystems respond to multiple stressor interactions at different spatial and temporal scales.
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The world’s ecosystems are experiencing an unprecedented increase in the number and variety of impacts that alter their ecological functioning. Such ecosystem alterations include changes to primary production, pollination, nutrient cycling and organic matter decomposition, among others.
Traditionally, ecologists have used species composition and other taxonomical approaches as indicators for ecosystem health. For example, some species are more likely to be abundant in disturbed sites, while others are very sensitive to human-caused stress. However, these techniques are not able to tell us how ecosystem functions might change after the disturbance, which would be far more useful for environmental managers in predicting and reacting to such impacts.
In a new study recently published in the Journal of Applied Ecology, we tested the potential of new functional indicators for assessing how river ecosystems respond to stress. We found that some of these indicators were able to detect single and combined effect of stressors, which may allow a better understanding of how freshwater ecosystem functioning responds to human pressures. Among them, functional redundancy is the most promising indicator as it relates positively to stability, resistance and resilience in ecosystems with a high sensitivity to stress.
The functional indicators used here account for the variability of the biological attributes of riparian vegetation (plants growing on land along river banks) that relate with ecosystem functioning, such as size, growth rate or leaf surface.
These measures have several advantages when compared to species-based tools. They have broader spatial utility (species composition varies more spatially than their biological attributes); better comparison among taxonomic groups (biological attributes as size are shared among all kind of organisms) and can be linked directly with ecosystem processes. There are many such links: leaf nutrient content affects in-stream processes like decomposition; larger trees cause more shadow which can alter river temperature and production and contribute to significant habitat modifications like natural, woody dams.
Riparian vegetation beside an intermittent river (Corneros River in Murcia, Spain), affected by drought in the Segura Basin study area.
Our study was conducted in a Mediterranean climate river basin (the Segura River) located in the southeast of Spain, where agricultural intensification, dams and natural droughts are the main causes of ecosystem stress. We produced different metrics to account for the multiple functional traits and aspects of the riparian plants. Then, we compared how those metrics responded to the single and combined stressors impacting on the ecosystem.
There were two main groups of functional indicators. First, measures of functional diversity which described the variability of biological attributes driving ecosystem functions. To measure functional diversity we calculated functional richness (community functional variability), functional evenness (how individuals or species are distributed among functional types) and functional dispersion (mean functional similarity among species);
Second, we used measures of functional redundancy, which can be defined as the number of species performing similar roles in an ecosystem, for example nutrient cycling, sediment fixation or climate regulation. Higher values of redundancy can mean increased long-term stability of related ecosystem functioning. This means that in functionally redundant ecosystems it may be possible for populations of some species to highly stressed or even made locally extinct, with little or no impact on ecosystem functioning.
One of the ways to estimate functional redundancy classifies species into functional groups which make similar contributions to ecosystem functioning. In our study, we classified riparian plants in five major functional groups: large highly water demanding trees; water demanding shrubs; evergreen shrubs; climbing plants; and drought-adapted vegetation.
Reach of the Mundo river in Albacete, Spain, which is disturbed by agricultural intensification. Note the scarcity of woody riparian vegetation in the left margin being dominated by evergreen shrubs and invasive species (e.g. Arundo donax).
Our results showed that stressors, when considered individually, caused general marked declines in functional indicators, with a variety in the size of decline. Generally, agricultural intensification was the most influential stressor for riparian functionality, followed by natural droughts. Hydrological regulation weakly affected functional indicators.
Functional redundancy was the most sensitive indicator in response to single and combined environmental filters. Combined effects on functional redundancy resulted from the interaction between agricultural impacts and droughts; and agricultural impacts and flow regulation. This suggests that such stressors should be considered together for the most accurate understanding of their effects on ecosystem health.
The most significant implication of these results is that functional redundancy can be used to identify which ecosystem functions are at the highest risk when an ecosystem is stressed. When we lose species from the same functional group (species playing a similar ecosystem function), this causes a decrease in functional redundancy. As such, using this functional index provides a valuable early warning system before ecosystem function begin to decline. Therefore, incorporating functional redundancy into river evaluation and management planning may help us to anticipate the effects caused by the ongoing global change.
Predicted functional redundancy for riparian communities in the Segura Basin study area.
An important advantage of the functional redundancy approach is its accurate response to combined stressors (best model explained near to 60% of its variability). We predicted the functional redundancy values for the entire river network (see figure above). For this forecast, we used a large dataset of sites from which agricultural intensification, flow regulation and natural drought were estimated, constituting a potential basis for biomonitoring and environmental management at the basin scale. This map is useful to detect the most impacted river reaches, to plan restoration measures, as well as to conserve the reaches with the best ecological functioning.
The predictors used here are low-cost, coarse-grain variables that are easy to obtain from digital maps and environmental databases. We also provide an open statistical method (R-scripts) to estimate the functional features and run the models showed in the study, allowing administrations and ecologists to extend this method to their study areas. Therefore, although the sensitiveness of functional redundancy to human impact must be specifically compared with other traditional biomonitoring tools and river types, it can be considered as an ecologically-sound measure able to detect ecological responses to single and multiple stressors.
Flussfisch: creative freshwater science communication through song
We’re always keen on creative science communication here on The Freshwater Blog. So when we were sent a new song resulting from a collaboration between freshwater scientist Simone Langhans and Swiss band Knuts Koffer, we knew we had to share it.
Built over a minimal, jazzy groove, the song’s lyrics (in German, with an English translation at the bottom of the post) are based on the research that Langhans – a post-doc at Leibniz-Institute of Freshwater Ecology and Inland Fisheries IGB in Berlin – has carried out on river restoration.
We spoke to her and primary songwriter Frédéric Zwicker to find out more about how this innovative collaboration came about.
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What have you been working on recently, and where?
Simone:
After my PhD in river and floodplain ecology at Eawag (Switzerland), I was working for the Swiss Federal Office for the Environment for a couple of years where I got interested in the challenges which we face when managing freshwater ecosystems. I’m particularly interested in ecological quality assessment, in methods that facilitate multi-stakeholder management decisions, and in optimizing river restoration with systematical planning approaches which account for cost-effectiveness.
Besides Switzerland, I’ve been working in Italy, Australia, Germany, and New Zealand. In my newest project affiliated with the Leibniz-Institute of Freshwater Ecology and Inland Fisheries in Berlin, I’m working with local Maori on New Zealand’s North Island to identify their cultural values related to their freshwater systems with the intention to learn about how cultural values can be used together with ecological values in freshwater management, also in Europe.
Frédéric:
I am basically working three jobs at the same time. Two and a half days a week I write for a construction magazine in order to not have to worry about my bills and have some structure in my otherwise often quite chaotic weeks. It’s pretty funny that a couple of months before Simone asked me to write the song I wrote an article on river-renaturation in northern Switzerland.
I also work as an author. I’ve been writing a satiric column for a newspaper for seven years, I perform poetry and my first novel is about to be released this year. So there’s journalism, literature and music. The fourth album of my band Knuts Koffer came out in November last year. At the moment we’re still touring with the current program but at the same time I’m working on new material and playing guitar and writing for other bands and projects.
What gave you the idea to communicate your scientific research through a song?
Simone:
Frédéric and I met by chance this summer in my hometown Rapperswil-Jona in Switzerland in the local pub, where I had beers with an old friend which we have in common. We started talking about our jobs (besides being a musician and fiction writer Frédéric writes for a Swiss construction journal) and suddenly this idea popped up in my head.
I have been intrigued by the idea that art could help convey scientific knowledge to the public for a while now, actually since my last year’s work stay in New Zealand where I got inspired by discussing similar ideas with my friend and colleague Dr. Marc Schallenberg (from the University of Otago). However so far, I never had the opportunity to work with musicians, although music has been part of my whole life, and I played in a band myself when I was younger.
Frédéric:
When Simone wrote to me I was immediately very excited about her idea. I am often inspired by science when writing songs or columns. One example: I read about scientific research on how men find women most attractive when they ovulate. I knew that in Switzerland two-thirds of women take the pill for birth control. The pill prevents women from ovulating. So 60% of Swiss women are never as beautiful as they could be. I had to put that into a song.
Simone’s project, however, required a more serious touch. I loved the idea to use very technical and scientific vocabulary in the lyrics and still make them rhyme without losing rhythm.
Simone Langhans. Image: technologiestiftung-berlin.de
Knuts Koffer. Image: clanx.ch
Tell us about the process of translating science into music and song lyrics. How did the collaboration work out? And how has the song been received?
Simone:
Since neither of us had ever worked on a project like this, we didn’t have a set workflow to follow. Instead we jumped right into it and decided on-the-go how to proceed from one step to the next.
In a question-answer type of way, I introduced Frédéric to the general background of my research and to the particular study the song should be about. We then discussed the messages of the song and how those could be structured in verses. In a next step, Frédéric wrote the lyrics, which we discussed again, and he also composed the music. I enjoyed the way we collaborated a lot – it felt very natural.
Most people I’ve talked to were excited about the idea right away, which encouraged me to go through with it, although it was risky to try something so new. I’m quite excited about the positive feedback we got so far. If there is a next time, we may try something in English to reach a larger, international audience.
Frédéric:
When Simone asked me to write the song I was very thrilled and agreed right away. Then, when she sent me the papers she had published, I had a bit of a shock. It would be very difficult to determine what was relevant and to turn several pages of scientific mumbo-jumbo (sorry, Simone) into a catchy song.
Then Simone and I sat down in my garden and she explained what her research was about. By the end of our first meeting we had drafted a content-plan for the different verses. After that it was just a matter of getting to work, writing the lyrics and adjusting them according to Simone’s inputs after a second meeting. I composed the music to reflect the tragedy of the status quo and the hope for a better future through Simone’s propositions.
The reactions were very positive. The construction magazine I work for is writing an article about the song. Quite a lot of people who know my band considered the song to be very funny. One friend even said it was her favourite song by my band. Of course I have mixed feelings about that…
What do you think the value of creative collaborations like this are? What advice might you be able to give to other people looking to foster similar interdisciplinary projects?
Simone:
Science itself is a very creative process and, hence, working with creative people from different fields is in my opinion inspiring on different levels. I directly benefited from this collaboration by:
1) Practicing how to formulate my research that non-scientists can understand what I’m doing and why;
2) Producing something other than a piece of paper that may have the potential to convey scientific knowledge to an audience outside of academia, and;
3) By getting a lot of feedback on my work compared to when I solely publish my research in scientific journals.
Networking and mingling with people outside of our scientific comfort zone is probably the key to interdisciplinary collaborations. I think we should also place more emphasis on them in project proposals to secure financial support for similar projects.
Frédéric:
We as a band (as well as Simone as a scientist) can present our work to a new audience which is always valuable. I think we can also both benefit from demonstrating how versatile we are. I’m definitely hoping for more similar commissions. I guess that for scientists proving that you’re able to think outside the box and have innovative ideas can be just as important as it is for musicians.
Of course it’s also financially interesting to diversify your offer and find new ways to earn some money, since the music industry and consumer-habits are not really making it easy to prosper as a musician. I definitely learned a lot working on this project. And last but not least it was great fun to do something out of the ordinary. So my advice to scientists with similar ideas is to contact me!
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RIVERFISH
A collaboration between Simone Langhans and KNUTS KOFFER
Mmh, Havel and Spree are two poor ladies
They lead a monotonic life captured in daily grind
Boats on their backs, bridges, channels, agoraphobia
Our rivers are not doing well because humans have screwed up
Now we’re planning restorations, but here a warning
We lack catchment-based and cost-efficient planning
Mmmmh, let’s systematize restorations
The software programme Marxan will assist us
It analyses potential restoration sites and shows us
The combination of sites that reaches the ecological goals at the lowest cost
Ahoi ho ho, ahoi ho ho, ahoi ho ho, ahoi ho ho
Havel and Spree should be healthy again these days
That’s anyway what the Water Framework Directive has envisaged
But the typical river fish species will never spawn sufficiently again
Cause there are not enough potential restoration sites to reach natural fish populations
Even so this is sad, thanks to the planning software we have realised
That restoration planning and Marxan are going hand in hand
Coupling expert knowledge and fish monitoring data
Marxan optimizes what’s best for flora, fauna and people’s wallet
Riiiiiiiiiii…….
The Leibniz-Institute of Freshwater Ecology and Inland Fisheries will continue working on these issues in order to improve the health of our rivers
………ver
There are a huge number of chemicals that can enter aquatic ecosystems, and join to form compounds. (Da = Dalton; CAS = Chemical Abstract System; WFD = Water Framework Directive) Figure: Werner Brack
Reporting on a new overview paper on Effect-Directed Analysis
Guest post by David López Herráez and Werner Brack.
Toxicants are a common source of stress to aquatic ecosystems, often acting in combination with other pressures such as river channel alterations, eutrophication, changes to water temperature and pH and invasive species.
Unravelling the combinations of different chemicals able to cause toxic stress to freshwaters is a really complex process, since such ‘cocktails’ can contain mixtures of substances drawn from 10⁶⁰ possible chemicals.
Ever tried to visualise such a huge number as ten to the power of sixty? SciencePie suggest a thought experiment that might help. Take 10⁶⁰ grains of sand and pile them up over the entire area of the United States of America. This would lead to a pile of sand with a height of around 15,000,000 times the diameter of the observable universe.
Do we have to analyse such a myriad of chemicals in order to understand toxic stress? Of course not. However, we need efficient and accurate tools to identify the chemicals that cause major stresses on aquatic organisms in a water body or river basin. If water quality monitoring and environmental management is only based on a pre-selected range of chemicals (such as the Water Framework Directive priority pollutants) we risk ignoring those chemicals that actually cause ecosystem effects. In turn, this approach risks focusing our monitoring and management resources on compounds of minor relevance.
What is Effect-Directed Analysis?
Effect-Directed Analysis (EDA) is one of the major approaches used to support the identification of toxic compounds at a specific site by combining chemical and biological analytical tools. It uses fractionation, a laboratory process which separates chemical mixtures allowing the determination of its different components. Although EDA has been used by environmental laboratories for over twenty years, a comprehensive compilation of EDA tools and recommendations for their efficient use was – until recently – missing.
Now, a group of 26 leading experts from Europe, U.S.A. and Canada have joined efforts to publish an in-depth overview on EDA over 46 pages of the journal Science of the Total Environment. This review provides a conceptual framework for the integration of EDA into water quality monitoring, and considers toxicant identification in diverse matrices (water, sediments and biota). Their work has been supported by the projects SOLUTIONS, EDA-EMERGE and the NORMAN Network on emerging pollutants.
Bioassays: unravelling chemical cocktails using biological indicators
As an effect-based approach, EDA is driven by the measurable effects of chemical mixtures extracted from these matrices using bioassays. Bioassays are biological analytical tools that detect effects of individual compounds and environmental mixtures on organisms and cellular systems, so called in vivo (on living organisms) and in vitro (on microorganisms and cells isolated from their normal environment) studies. In vivo bioassays typically use representatives of major organism groups also addressed as Biological Quality Elements in the Water Framework Directive including algae, invertebrates (e.g. Daphnia) and fish (e.g. zebrafish embryos).
Daphnia as test organisms. Images: Andre Künzelmann.
Zebrafish as test organisms. Images: Andre Künzelmann.
In vitro bioassays often directly address specific modes of action including the metabolism of chemicals, hormonal disruption, inhibition of specific enzymes, DNA damage or adaptive stress responses. All these assays represent links in adverse outcome pathways following the concept that key events at the cellular level (e.g. the reaction of a chemical with DNA) may be mitigated by adaptive stress responses or, if repair capacity is exceeded, may lead to cascading effects on organisms, populations and even ecosystems.
Getting meaningful results from small samples
An EDA study typically involves the analysis of many samples and fractions which are only available in small amounts. Therefore, in addition to the biological response requirements of a sample, it also ideally needs to be processed at a fast rate (known as high throughput) and at low volumes. The new review lists the frequently used high throughput bioassays for EDA, along with their respective advantages and disadvantages, confounding factors, volumes and dosing formats.
Prioritisation, or listing in order of (in this case) toxic priority, of compounds contributing most to observed effects is the major task of effect-directed analysis. This may succeed only if the relative composition of a mixture of chemicals exposed to a test organism in the lab is similar to the mixture the organism would encounter in the field. The way in which extracts of sediments or water are dosed into bioassays very much determines the mixture taken up by the test organisms, and thus the priority setting.
In sediments, the mixture of chemicals to which a benthic organism is exposed is the result of partitioning (or otherwise stated: the ratio of concentrations) of all its components among sediment particles, water and the organism, while in the lab simple transfer by extraction and dissolution are predominant. In the overview paper, a thought experiment suggests that conventional dosing of sediment extracts may result in a strong bias in toxicant prioritisation, being recommended to load sediment extracts into silicone or other devices mimicking the natural conditions.
Different EDA tools: fractionation and mass spectrometry
In order to divide toxic chemicals and combinations from the bulk of inconspicuous ones, we need fractionation tools, typically chromatography, which reduce the chemical complexity of a sample in a smart way. That means we have to fractionate without losing our original toxicity; we need optimal selectivity for relevant chemical groups, and we should learn as much as possible about the properties of the chemicals ending up in the fractions. The overview paper brings together a great deal of the available research and experience to help design tailor-made fractionation procedures in the future.
When toxic effects (and the chemicals that cause them) are isolated in specific fractions, high-end analytical chemistry comes into play. High resolution mass spectrometry coupled to gas and liquid chromatography helps to identify the molecular formulas of the components in our toxic fractions. These formulas tell us the type and number of atoms involved in forming a molecule. However, they don’t tell us how these atoms are bonded to a chemical structure.
Many hundreds, even thousands of chemical structures with completely different properties and toxicities are possible, despite being described by the same molecular formula. The overview paper explains how it is possible to sequentially reduce the number of candidate chemical structures by comparing observations for the compounds in a sample such as chromatographic retention, ionization and fragmentation in mass spectrometry and toxic effects with predictions for candidate structures. This also involves a assemblage of computational prediction tools.
Clever SOLUTIONS for complex chemical problems
The marriage of advanced analytical and bio-analytical tools with rapidly developing computational prediction tools opens a very promising future for toxicant identification. Hopefully, this extensive overview paper can support this process and help to increase the applicability and success rate of effect-directed analysis in environmental monitoring.
Eutrophication in a European canal. Image: Wikipedia
When an aquatic ecosystem is loaded with excess nutrients – from detergents, fertilisers or sewage, for example – algal blooms often occur. High levels of nutrients such as nitrogen and phosphate in a water body can cause rapid growth of plants and algae, which can ‘choke’ the ecosystem of light and oxygen.
When algae die and decompose, the nutrients they contain are converted into inorganic forms by microorganisms, a process which consumes oxygen. This means that decomposing algal blooms can starve an aquatic ecosystem of dissolved oxygen, which is vital for fish populations. Waterbodies with low dissolved oxygen are described as anoxic, or in extreme cases as experiencing hypoxia.
These ecological responses to increased nutrient levels are often called eutrophication. Eutrophication can be a natural process, occurring over long timescales in response to climatic changes and geological weathering, but is vastly accelerated in both speed and impact by nutrient pollution from human activity.
Eutrophication has become a major environmental issue in lakes, canals and slow flowing rivers in Europe and North America since the mid-20th century. Its impacts can vary, but often include reductions in freshwater biodiversity, fish kills, increases in water toxicity and cloudiness, and the resulting need for increased water treatment to produce safe, clean drinking water.
In Europe, the adoption of the Water Framework Directive in 2000 has forced national governments to take steps to reduce nutrient pollution in lakes and rivers. Many lakes that became dominated by phytoplankton under eutrophication are now recovering, and supporting increasingly diverse and healthy ecosystems.
A water lily in Westfalenpark, Dortmund. Water lilies are an example of macrophytes. Image: Mathias Appel | Flickr Creative Commons
Ecological monitoring procedures using biological quality elements – such as phytoplankton or aquatic plant (or macrophyte) populations – are used to help scientists track the ecological recovery of freshwaters in response to reduced nutrient levels. Existing studies have found that macrophyte recovery may be delayed, whereas phytoplankton levels often showed almost immediate reductions.
Delayed macrophyte growth is likely to be due to longer generational time, dispersal limitations, and a lack of viable seed banks for regrowth. As such, macrophytes’ complex and variable responses to reduced nutrient pollution make them potentially unreliable biological indicators for surveying water quality, at least in the short term.
Over longer periods, the restoration and regrowth of a formerly eutrophic ecosystem is likely to be dominated by new plant communities. However in the short term (e.g. from season to season) phytoplankton levels are generally used to provide the best indicator for water quality changes, which are then reported to the Water Framework Directive monitoring program.
Durinskia baltica, a type of phytoplankton, under an electron scanning micrograph. Image: FWC | Flickr Creative Commons
A new study, published in the journal Ecological Indicators, tests the responses of macrophyte and phytoplankton communities to reductions in nutrient levels in lakes. The study, led by Falk Eigemann from the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Germany, assessed 263 German lakes recovering from historical nutrient pollution and eutrophication between 2003-2012.
The study found that a lake’s ecological status was recorded as lower when using macrophytes as a biological quality element, as compared to when phytoplankton. This is due to the lag in response of macrophyte populations to reduced nutrient levels in the ecosystem.
Longer-term data (beginning in the 1980s) from five lowland lakes where phosphorus levels had been reduced showed that phytoplankton levels indicated a constant improvement in ecological status which tracked decreases in nutrient levels. Macrophytes, on the other hand, showed a 10-20 year delay in their ecological recovery.
Lake Tollensesee in Germany, one of the longer-term studies. Nutrient levels in the lake have been reduced as a result of improved wastewater treatment. Image: Sören | Flickr Creative Commons
There are two important points to take from this study. First, the study’s authors confirm that the way ecological status is measured (i.e. the choice of indicator) affects monitoring results. However, the parallel reductions in phytoplankton levels in response to decreasing nutrient levels confirm its usefulness as a bioindicator.
Second, and more broadly, the study demonstrates how ecological recovery and restoration is a slow process, even when measures such as nutrient reduction are put in place. As the authors of this study put it, “each lake ecosystem is unique and thus responds differently. When sufficiently low nutrient concentrations have been achieved, still patience may be needed when anticipating an improved ecological lake status.”
The study suggests that in German lakes, aquatic plant communities may take decades to regrow after eutrophication. Even where political and public will is in place, ecological recovery is often a slow, and potentially unpredictable, process.
Multiple stressor indicators, interactions and impacts at a MARS workshop in Lisbon
In December 2015, a team of MARS scientists responsible for investigating and modelling the effects of multiple stressors on river basins across Europe held a project workshop in Lisbon, Portugal. The workshop discussions – organised by Teresa Ferreira – are shown here in a series of pictures taken by MARS scientist Christian Feld.
A key topic at the workshop was to analyse ongoing data about how biological indicators, such as fish abundance, are affected by multiple stressors, such as habitat loss or pollution, at the river basin scale. Here, the team sought to identify most important stressors and, if present, their interactions.
Christian Feld explains how multiple stressors can interact in freshwater ecosystems:
Stressor interactions mean that two stressors – for example, increases in nutrient concentrations and water temperature – act together to create problematic ecological effects.
Here, we have a typical example of ‘synergistic’ stressors, which interact and together increase their individual effects. In other words, the joint effect of nutrient pollution and increased temperatures is more than the sum of individual effects.
The other main type of multiple stressor interaction is antagonistic, which is when one stressor (in part) reduces the effect of another.
Understanding the interactions and impacts of multiple stressors on freshwater ecosystems is one of the key challenges for the MARS project. In an increasingly human-impacted world, most ecosystems are subject to numerous stresses from many sources. An awareness how these stressors interact is therefore important for guiding environmental management, policy and conservation.
For example, restoration and conservation efforts on a river which is in poor ecological health as a result of pollution, habitat loss and invasive species need to understand the interactions between these multiple stressors in managing their mitigation.
If there are antagonistic interactions, management of a single stressor could lead to the effects of its interactive pair becoming stronger. Restoration and conservation efforts which focus on single stressors might therefore have unexpected outcomes for the health and diversity of an ecosystem.
Participants at the Lisbon workshop agreed on a standardised procedure for analysing stressor interactions, which can be applied across all European river basins. The results of these analyses will feed into that of other MARS teams who are synthesising data on multiple stressor impacts and interactions at the European scale.
Christian Feld explains why this work is important:
We wish to see if multiple stressor patterns and results are comparable across Europe; and across streams, rivers, lakes and estuaries.
We want to know which organisms are the best indicators of multiple stressors (fish, invertebrates, plants); and we wish to know which stressors and stressor combinations act at broad (continental) scales, and which act rather regionally or locally.
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