Lakes in the long term
A guest blog by Dr. Stephen Thackeray, a lake ecologist at the Centre for Ecology & Hydrology.
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A cold wind bites and stiffens fingers that deftly prepare the probe for its descent. Moments later the instrument slips through the surface and glides from well-lit to ever-darker waters, where it will gather important data on the living conditions experienced by the hidden life of the lake. This is a world unseen. A world of constant change, where warmth, light, nourishment and danger vary hugely in time and space. It is also a place of super-abundant life.
This event is the latest episode in a multi-decade scientific endeavour that has tracked the changing fortunes of some of England’s most iconic lakes in Cumbria; a landscape now endowed with UNESCO World Heritage Status. Data from this ongoing year-round research, initiated by the Freshwater Biological Association in the 1940s and continued by the Centre for Ecology & Hydrology since 1989, tells a story of long-term change in the physical, chemical and biological conditions of the lakes. In Windermere, it is a story of decades of nutrient enrichment caused by sewage inputs and agricultural run-off and, increasingly, a story of climate change.
The lake supports a bewilderingly complex web of life. Microscopic plants and animals, organisms that challenge our perceptions of what distinguishes these groups, along with larger invertebrates and fish coexist there. Competitors, predators, prey, cannibals, parasites. Environmental change affects them all.
Our long-term records allow us to trace these effects. Our lake monitoring has shown increases in algal growth in response to rising phosphorus concentrations, including increases in the prevalence of blue-green algae. Sediments accumulated in the darkest recesses of the lake interior provide us with an even longer-term view of these changes. Deposited ‘mud’, although opaque and turbid, provides a window into the distant past. Such records have clearly shown how changing wastewater treatment has affected the algae of the lake.
Though the fossil record suggests that blue-green algae have existed for billions of years, excessive growth can affect water taste and odour, raise treatment costs, and result in unsightly scums. Research at this iconic lake prompted sewage treatment improvements in the early 1990s, in order to address these issues.
Over the same time period that the lake has been enriched with nutrients, it has also warmed. Even winter temperatures have been rising. With warming has come a shift in the underwater seasons, with spring plankton blooms shifting earlier in the year, as well as spawning times for perch. However, perch spawning times have not kept pace with changes in the seasonal timing of plankton food resources, meaning that larval perch may emerge out of sync with their main food resource.
This change in nature’s calendar might already be affecting the survival of the young fish. The fortunes of other fish species have been changing too. Over the same long time scales we have seen that catches of the cold-water Arctic charr, a fish similar to trout and salmon, have greatly declined, while numbers of warm-water roach and bream have increased.
We have these exceptional records, objectively documenting ecological change more accurately than the shifting baselines of generational memories, thanks to the ongoing efforts and dedication of skilled field researchers. The Cumbrian lakes are sentinels, helping us understand the consequences of climate change, and other emerging environmental issues.
However, their relevance is not restricted only to northern England. Just as the species within these lakes are interconnected, so too are researchers across the world. Data and ideas flow through this network, as energy flows through a food web, creating opportunities to collaborate, learn, and build a global picture of how life beneath the water surface is changing.
As such, records from the Cumbrian Lakes are increasingly being used in large-scale scientific investigations into pressing environmental issues that will have global implications. Continuation of this vital work is more important than ever.
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Europe’s largest dam removal project so far took a significant step forward last week as the first breach was made in the 36-metre high Vezins Dam in Normandy, France. The dam, located on the Sélune River, was been scheduled for dismantling in 2017, along with another 15-metre high dam, La Roche-Qui-Boit.
The removal of the dams is designed to reconnect migration routes for fish such as the Atlantic Salmon and European Eel, and to improve water quality in the river and re-naturalise flows of sediment through the Sélune catchment. The story here is indicative of global trends: a recent study suggests that only around one-third of global rivers are free-flowing – with dam construction a key factor in fragmenting and regulating water flows.
The La Roche-Qui-Boit and Vezins dams were built on the Sélune in 1914 and 1927 respectively. Before their construction, migratory fish could move throughout the river’s catchment between their spawning grounds in tributaries and headwaters and their feeding grounds out at sea. The dams provided an impassable obstacle for salmon, limiting their spawning grounds to a small area below the dams. Removal of the dams will open up 90km of the Sélune River to migratory fish, which is estimated to increase juvenile salmon habitat three-fold, and increase adult salmon numbers returning to the river by more than 1400.
Large reservoirs of slow-moving water have formed behind the dam walls, where river sediments are prevented from moving downstream towards the river estuary at Mont St Michel. This has two linked ecological problems. First, the build-up of sediments and reduction in water flow can lead to algae blooms and reductions in water quality. Second, the dams disconnect natural sediment flows throughout the river catchment, altering how material and nutrients flow through the river system. In effect, dams don’t only fragment water flows along a river system, but also disconnect its ecosystems and their natural processes.
“The removal of the Vezins Dam signals a revolution in Europe’s attitude to its rivers: instead of building new dams, countries are rebuilding healthy rivers and bringing back biodiversity,” said Roberto Epple, president of European Rivers Network. “Nature can recover remarkably quickly when dams are removed and I look forward to watching salmon swimming past Mont St Michel and spawning in the headwaters of the Sélune for the first time since my grandparents were young.” Epple continued.
The Vezins and La Roche-Qui-Boit dams were both built around a century ago, and campaigners argue that they are now inefficient and obsolete, and that their environmental impact outweighs their ability to produce renewable energy. “There are tens of thousands of old, obsolete dams in Europe that can and should be removed,” said Arjan Berkhuysen, managing director of the World Fish Migration Foundation. “We are hopeful that by removing not only big dams like this but also by removing small barriers through local efforts we can restore these important life sources.”
A 2018 BBC Radio 4 programme interviewed some of the river restoration practitioners involved in the Sélune River project, outlining that the first phase of the project was to empty the lake above the Vezins dam, and stabilise its sediments. This process has now been completed, allowing for last week’s first breach of the dam wall itself. The smaller La Roche-Qui-Boit dam is due to be demolished in 2021.
The dismantling of the dams on the Sélune River will provide a valuable case-study for environmental scientists and policy makers seeking to understand how river ecosystems respond to dam removal. The scientific project responsible for the dam removal has a 16 year ‘lifespan’ to monitor the river’s ecosystems for years to come. Similar large-scale projects, such as the removal of the 64-metre high Glines Canyon Dam on the Elwha River in Washington State, USA have resulted in increasing migratory fish populations, and the creation of new habitats due to naturalised sediment flows, both along the river and out into its estuary.
The Sélune River dam removal project has been opposed by some members of the local community, partly because of the recreation and tourism value of the lakes created above the dam walls. A recent analysis of the evolution of the Sélune project suggests that such discord stems from the difficulties of creating meaningful dialogue and ‘shared visions’ for the landscape in decision-making processes.
As the shifting-baseline theory suggests, what people might imagine as a defining feature of a place – such as a dam lake – can often be a relatively recent alteration to the landscape. What dam removal asks us to do – ecologically, politically, and aesthetically – is to imagine river landscapes unconstrained by human actions, and instead with resurgent ability to plot their own course. This, of course, is not always an easy process to get everyone on board with.
The Sélune project is taking place at the same time as major hydropower construction projects threaten the health and status of free-flowing rivers in Eastern Europe, and across the world. Clearly, despite this hopeful project there is significant work to be done in balancing the need for renewable energy with the critical need to conserve and restore freshwater biodiversity. We will follow these projects closely in the coming months.
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Microplastic pollution is an increasingly widespread issue in both freshwater and marine ecosystems across the world. It is estimated that more than 8.3 billion tonnes of plastic has been created since the 1950s, with more than half of this figure produced in the last 13 years. Plastic pollution is an issue which spans terrestrial, freshwater and marine ecosystems: it is estimated that a fifth of the plastic entering the world’s oceans is transported by rivers.
Plastic fragments smaller than 5mm are known as microplastics. Research suggests that because of their potential uptake and transmission through food webs, microplastics prompt a significant, but poorly understood, threat to aquatic life.
A new study adds to this growing knowledge base, suggesting that microplastics are readily colonised by aquatic microorganisms, which could lead to the growth of toxin-producing plankton species.
Researchers from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) and the Leibniz Institute for Baltic Sea Research, Warnemünde (IOW) incubated polyethylene and polystyrene microplastics with natural microfauna at different stations in northern Germany: the Baltic Sea at Heiligendamm, the lower River Warnow and a wastewater treatment plant.
Their results, published in the Frontiers in Microbiology journal, show how microplastics act as valuable micro-habitats for microorganism colonisation, with over 500 different species observed from the 15-day experiment. The researchers suggest that a plastic item weighing one gram, floating in the sea, can support more living organisms than a thousand litres of surrounding seawater.
“Microplastics may represent a significant habitat and transport medium for microorganisms. Our experiments showed that microorganisms, such as Pfiesteria piscicida, enrich on plastic items, where they exhibit much higher densities than in the surrounding water or on driftwood,” said Dr. Maria Therese Kettner from IGB.
The dinoflagellate Pfiesteria piscicida highlighted by Dr. Kettner was the most common coloniser of microplastics in the study. It was observed at densities around fifty times as high as in the surrounding water, and around two to three times as high as on comparable wood particles.
Pfiesteria piscicida is a potentially toxic plankton species – its Latin name means ‘fish killer’ – which presents a significant threat to human and animal life at high concentrations. In addition, the dinoflagellate Heterocapsa – known for toxic ‘red tide’ blooms which can cause mass mortality of bivalves – was observed as another microplastic coloniser. In short, the study suggests that microplastic pollution may act as a catalyst for toxic plankton blooms.
IGB researcher Prof. Hans-Peter Grossart, who led the study, highlighted another key finding: “Unlike natural substances such as wood or colonies of algae, microplastic particles decay extremely slowly, and may therefore transport the organisms they host over long distances.” In other words, microplastics may provide a durable dispersal medium for harmful microorganisms, which could potentially be carried over long distances by rivers and ocean currents.
“However, communities on microplastic particles often change when they ‘travel’ and adapt to their new environment,” said marine microbiologist Dr. Matthias Labrenz. “Therefore, these aspects need further investigation,” suggested the IOW researcher. Research and policy on ‘invasive’ aquatic species often focuses on transport mechanisms such as shipping: this study suggests that microplastics may act as a vector for introducing potentially harmful microorganisms into new environments.
The researchers raises a third issue, suggesting that colonised microplastics have the potential to change carbon, nutrient and energy dynamics in aquatic environments. Recent research suggests that cyanobacteria which have colonised microplastics exhibit increased photosynthetic activity. Dr. Kettner and colleagues suggest that since numerous algae species were detected in this study, an increase in photosynthetic activity in areas of microplastic pollution could be expected.
The research team highlight that colonised microplastic particles add to the overall load of organic aggregates in marine environments. Some of these particles are likely to be transported vertically between the sea surface and floor by ocean currents. As a result, the researchers suggest that microplastic colonisation observed in the study has the potential to affect the oceanic carbon pump and vertical fluxes of nutrients in marine environments.
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Marie Therese Kettner; Sonja Oberbeckmann; Matthias Labrenz; Hans-Peter Grossart, (2019) “The eukaryotic life on microplastics in brackish ecosystems” Frontiers in Microbiology, 10 art. 538 (open-access)
Europe’s aquatic ‘life support system’: good ecological condition correlates with ecosystem service provision
European aquatic ecosystems can better provide vital services – such as water purification and flood protection – to humans when they are in good ecological condition, according to a new study. These findings highlight the need to protect and restore European waters, not only for the non-human lives they support, but also for the health and well-being of human communities.
Bruna Grizzetti and colleagues mapped European aquatic ecosystem services in relation to ecological conditions in rivers, lakes, groundwaters, coastal and transitional waters, floodplains, riparian areas and wetlands across the continent.
They found that there was a strong correlation between the delivery of regulating and cultural ecosystem services and good ecological condition. In other words, when aquatic ecosystems have abundant biodiversity, sufficient habitat and non-harmful chemical conditions, they are generally better at providing water purification, erosion retention, flood protection and coastal protection services. In addition, the authors suggest that recreation services – such as tourism – are generally increased in ecosystems with good ecological condition.
On the other hand, Grizzetti and colleagues found that provisioning services were correlated with poor ecological conditions. This is because their measure of provisioning services is based on water abstraction – an extractive process which is likely to negatively alter habitat and water availability in an ecosystem.
What are ecosystem services?
Ecosystem services are the many and varied benefits that ecosystems provide to humans. They are grouped in four categories: supporting services (e.g. nutrient cycling), provisioning services (e.g. food production), regulating services (e.g. water purification), and cultural services (e.g. recreation opportunities).
The logic behind the ecosystem services concept is that if the wide-ranging benefits humans derive from the environment can be quantified and communicated, then the argument for conserving and restoring ecosystems will be strengthened.
Grizzetti and colleagues mapped six aquatic ecosystem services in their study: water provisioning, water purification (through nutrient retention), flood protection (by floodplains), natural coastal protection, and recreation value. For each service, measures of natural capacity (i.e. the potential of the ecosystem to provide the service), flow (i.e. the actual use of the service), sustainability (i.e. flow compared to capacity), efficiency and human benefits were calculated and mapped.
What is ecological condition?
The researchers calculated ecological condition across Europe using monitoring data for ecological status taken by Member States under the Water Framework Directive.
Ecological status is a measure of the abundance and composition of different organisms in a food web and the habitat and chemical conditions of an aquatic environment, and represents an integrative measure of the condition of the water body. Data on ecological status in 79,630 water bodies across the EU was used to map ecological condition in this study.
Good ecological condition promotes ecosystem service provision
The research team, supported by the Joint Research Centre of the European Commission and the EU FP7 projects MARS and GLOBAQUA, recently published their findings in an open-access paper in the journal Science of the Total Environment.
They suggest that their findings support calls to protect and restore aquatic ecosystems through the EU Water Framework Directive and Biodiversity Strategy, the United Nations Sustainable Development Goals (SDG 6 – Clean Water and Sanitation and SDG15 – Life on Land), and the Convention on Biological Diversity.
Study co-author Olga Vigiak said: “We mapped freshwater ecosystem services in Europe and put them in relation with the ecosystem condition. Regulating and cultural services (like water purification, erosion prevention, flood and coastal protection, and recreation) were correlated with good ecosystem status.
Conversely, provisioning services (i.e. water abstractions for domestic and economic activities) put pressure on aquatic ecosystems. The study supports the need to protect and restore aquatic ecosystems to ensure the delivery of vital ecosystem services in the future.”
A key takeaway point from this study is the extent to which daily human lives rely on healthy functioning natural environments. In an increasingly urbanised world, this connection is not always perceivable, but what Grizzetti and colleagues’ study shows is that aquatic ecosystems in Europe form a giant ‘life support system’ for both human and non-human communities. It is in all of our best interests to protect and restore them.
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Grizzetti, B. et al (2019), Relationship between ecological condition and ecosystem services in European rivers, lakes and coastal waters, Science of The Total Environment, Volume 671, 25 June 2019, Pages 452-465
A landmark global report summarised earlier this week suggests that around 1 million animal and plant species are threatened with extinction. For many species, extinction could occur within decades. The global rate of species extinction is already at least tens to hundreds of times higher than the average rate over the past 10 million years and is accelerating, the report states.
The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Global Assessment Report on Biodiversity and Ecosystem Services outlines the state of knowledge regarding the planet’s ecosystems and the contributions they make to people.
Compiled by 145 expert authors from 50 countries over the past three years, with inputs from another 310 contributing authors, the Report assesses changes to biodiversity and ecosystems over the past five decades.
“The overwhelming evidence of the IPBES Global Assessment, from a wide range of different fields of knowledge, presents an ominous picture,” said IPBES Chair, Sir Robert Watson. “The health of ecosystems on which we and all other species depend is deteriorating more rapidly than ever. We are eroding the very foundations of our economies, livelihoods, food security, health and quality of life worldwide.”
“The Report also tells us that it is not too late to make a difference, but only if we start now at every level from local to global,” he said. “Through ‘transformative change’, nature can still be conserved, restored and used sustainably – this is also key to meeting most other global goals. By transformative change, we mean a fundamental, system-wide reorganization across technological, economic and social factors, including paradigms, goals and values.”
Based on the review of around 15,000 scientific and government sources, the IPBES Report also draws on indigenous and local knowledge. It outlines the relationships between economic development pathways and their impacts on nature, and offers a range of possible scenarios for the coming decades.
“Ecosystems, species, wild populations, local varieties and breeds of domesticated plants and animals are shrinking, deteriorating or vanishing. The essential, interconnected web of life on Earth is getting smaller and increasingly frayed,” said Assessment co-chair Prof. Josef Settele from the Helmholtz-Centre for Environmental Research (UFZ). “This loss is a direct result of human activity and constitutes a direct threat to human well-being in all regions of the world.”
What does the IPBES Report tell us about the state of global freshwater environments?
1. Land use change is the key driver of freshwater ecosystem decline
The IPBES Report ranks the five key drivers of freshwater ecosystem decline and biodiversity loss. The drivers are, in descending order: (1) changes in land use; (2) direct exploitation of organisms; (3) climate change; (4) pollution and (5) invasive alien species.
Agriculture is a key part of this picture: more than a third of the world’s land surface, and nearly 75% of freshwater resources, are now devoted to crop or livestock production. Agriculture can have numerous impacts on freshwater ecosystems, including fertiliser and pesticide pollution, habitat loss, water extraction, and alterations to waterways themselves.
The IPBES Report notes that greenhouse gas emissions have doubled since 1980, raising average global temperatures by at least 0.7 degrees Celsius. Climate change is predicted to be an increasingly powerful driver of ecosystem change and biodiversity loss in coming decades: shifting species distributions, changing phenology, altering population dynamics and the composition of species assemblages, as well as interacting with other drivers such as land use change.
2. Aquatic pollution is significant and widespread
Water pollution is one of the five key drivers of freshwater ecosystem degradation. Excessive or inappropriate application of agricultural fertilisers can lead to run off from fields entering freshwater and coastal ecosystems. Such pollution has caused more than 400 hypoxic ‘dead’ zones in coastal and transitional waters globally since 2008, affecting a total area of more than 245,000 km2 – an area larger than the United Kingdom.
The IPBES Report suggests that more than 80% of global wastewater is discharged untreated into the environment, causing nutrients, chemicals, bacteria, microplastics and many other pollutants to enter waterways. Such pollution ‘cocktails’ can have numerous, long-lasting effects on both human and non-human life.
Globally, plastic pollution has increased ten-fold since 1980. In freshwaters, ongoing research is showing how both plastics, and the microplastics they break down into, can have significant effects on aquatic life. A startling 300-400 million tons of heavy metals, solvents, toxic sludge and other wastes from industrial facilities are dumped annually into the world’s waters.
3. Wetlands are being lost at alarming rate
The IPBES Report states that indicators suggest that global ecosystem extent and condition has decreased, on average, by 47% compared to estimated ‘natural’ baselines. Many global ecosystems continue to decline in extent and condition by at least 4% per decade. It is estimated that ecological and evolutionary processes still operate with minimal human intervention in only around a quarter of terrestrial and freshwater ecosystems.
Wetlands are disappearing across the world at an alarming rate, the IPBES Report suggests. More than 85% of wetlands present in 1700 had been lost by 2000. The loss of global wetlands (0.8% per year between 1970 to 2008) is currently three times faster, in percentage terms, than global forest loss. Wetlands are extremely valuable ecosystems, not only providing habitat for both resident and migratory species, but also providing services such as water filtration and flood buffering to humans.
4. Amphibians are particularly threatened with extinction
The IPBES Report states that, on average, 25% of species across terrestrial, freshwater and marine vertebrate, invertebrate and plant groups that have been studied in sufficient detail are threatened with extinction.
Amphibians are particularly threatened, with more than 40% of amphibian species – many of which rely on freshwater ecosystems – at risk of extinction globally. Amphibian species across the world are impacted by habitat loss, climate change, and the the spread of the deadly fungal disease chytridiomycosis. A 2011 study in Nature suggests that areas of greatest amphibian species richness are often the same areas subject to the greatest combined threat of habitat loss and climate change.
5. Governance options exist to protect and restore freshwater ecosystems
The IPBES Report emphasises the role of unsustainable human activities in driving global biodiversity loss, and highlights the need for widespread political and economic change to safeguard the future of life on Earth.
Freshwater systems are given significant attention, with the IPBES Report authors emphasising that sustaining freshwater in the context of climate change, rising demand for water extraction and increased levels of pollution requires significant cross-sectoral policy interventions.
Key policy priorities including: more inclusive water governance for collaborative water management; better integration of water resource management and landscape planning across scales; promoting practices to reduce soil erosion, sedimentation and pollution run-off; increasing water storage; promoting investment in water projects with clear sustainability criteria; and addressing the fragmentation of many freshwater policies.
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Acoustic monitoring of freshwater ecosystems: Costa Rica study reveals diverse underwater soundscapes
The study site – Cantanara Swamp at La Selva Biological Station in Costa Rica. Image: Ben Gottesman.
Freshwater ecosystems across the world are disproportionately threatened by human activity, causing ongoing losses of aquatic biodiversity globally. Many freshwater conservationists highlight the need for more comprehensive ecological monitoring and assessment programmes to better understand ecosystem changes, and to strengthen conservation initiatives accordingly.
An innovative new study seeks to address this need using an unusual approach: acoustic monitoring of freshwater soundscapes. A soundscape is the aural equivalent of a visual landscape: all the sounds we hear in a space (whether through our ears, or through recording devices), emitted by both human and non-human sources. Soundscapes are never static, often varying with the time of day, weather conditions and human activity.
Researchers from Purdue University, USA and Nanjing University of Science and Technology, China recorded the aquatic soundscape of a Neotropical freshwater swamp in Costa Rica for 23 days in 2015. They used special underwater microphones – known as hydrophones – to delve into the acoustic world of the freshwater wetland. They wanted to better understand how soundscape recording might enhance existing freshwater ecosystem monitoring and assessment initiatives.
The promise of soundscape ecology
Soundscape ecology is a growing inter-discipline, popularised by the sound recordist Bernie Krause and the ecologist Bryan Pijanowski (Director of the Center for Global Soundscapes who led this study), amongst others. By recording soundscapes, it may be possible to gain a picture of the biological community present in an area, and to assess animal activity patterns. Such approaches have numerous benefits to ecologists: being non-invasive, offering high temporal resolution, facilitating long-term sampling strategies in remote areas, and providing an archive of detailed digital data for long-term analyses.
However, soundscape recording approaches have – as yet – been largely confined to terrestrial (e.g. bats and birds) and marine ecosystems (e.g. whales and dolphins). The research team behind the new study – published in Freshwater Biology – suggest that soundscape recording can provide a valuable tool in difficult-to-access aquatic environments where visibility is limited, and sound is a principle means of animal communication.
Lead author Ben Gottesman, a PhD Candidate at Purdue University’s Center for Global Soundscapes, explains, “The sounds of freshwater habitats are still mostly a mystery, especially in the tropics. Rainforests are noisy places, filled with sounds of birds, bugs and amphibians. But what about underwater? Is there a similar sort of cacophony in the forested wetlands?”
Such sonic explorations aren’t solely driven by curiosity, but could also yield valuable environmental data, Gottesman suggests, “If you are like my skeptical grandpa, you may be wondering why we would care about aquatic soundscapes? The reason is because these sounds could unlock an efficient and effective way to monitor freshwater biodiversity, which is rapidly declining and can be difficult and costly to measure.”
The paper is part of a special issue of Freshwater Biology exploring the potential of acoustic methods for freshwater ecology. Other papers cover topics including acoustic monitoring of piranhas in Peru, lesser water boatmen in a Mediterranean pond, and toads in Northern France; and the possibility of ‘acoustic refuges’ in fish habitats.
Exploring the underwater sounds of a Costa Rica wetland
The research team submerged a hydrophone connected to an automated acoustic recorder in the Cantanara Swamp in Costa Rica – known for its richness of amphibian, bird, mammal and invertebrate species. Their equipment recorded 10 minutes of underwater sound each hour, and 1 minute each 15 minutes. This sampling strategy created 2,121 sound recording ‘snapshots’ from the swamp over the 23 day fieldwork period.
Ben Gottesman outlines the aims of the study, “Our goals were to assess the diversity of sounds within this wetland and also the temporal dynamics. We found rich diversity in sound types – eighteen in all.
“We were surprised by the daily soundscape dynamics. Whereas the day-time and night-time soundscapes were filled with the clicks, stridulations and buzzes of aquatic insects, dusk and dawn were notably quiet. We posited several explanations for these crepuscular lulls, but still do not have a definitive answer.”
Spectrograms and oscillograms (below the spectrograms) of eight sound types from the study. Time (seconds) is on the x-axis and Frequency (kHz) is on the y-axis of spectrograms. See all eighteen sound types here.
Classifying underwater ‘sound types’ from the wetland soundscape
The eighteen sound types – creatively termed ‘Cyclops’, ‘Geiger’, and ‘Highchair’ amongst others – were classified based on their audible differences, and the visual patterns they generated in a spectogram. Spectograms are a visual representation of the spectrum of frequencies of an audio signal over time. The frequencies of the recorded sound types spanned a huge audio spectrum: from below 100 Hz (sub harmonic frequencies below human hearing) to above 22 kHz (higher than the sounds made by most mosquitoes).
Whilst the sound types have yet to be identified to their animal sources, the study shows that there was a rich diversity of underwater sounds emitted in the Cantarana Swamp, forming a soundscape with distinct daily dynamics.
“We are still in the early stages of classifying freshwater sounds and identifying the ecological factors that influence soundscape diversity and dynamics. Both of these are basic steps necessary for acoustic monitoring to become useful as a freshwater habitat assessment tool,” says Gottesman. “This study illustrates that healthy tropical wetlands like this one can contain rich soundscapes, and are therefore promising sites for acoustic monitoring.”
Acoustic monitoring: a valuable new method for freshwater science and conservation?
The study authors suggest that there are a number of necessary steps for freshwater acoustic monitoring and assessment techniques to become more widely used. These include ‘ground-truthing’ soundscape data with in situ field samples of biological and environmental conditions, and creating ‘field guides’ of the sounds emitted by individual species.
The authors state that for soundscape methods to be effective in freshwater environments, their measurements must have a strong positive correlation with at least one measure of biodiversity, such as species richness or abundance. Clearly, this is an emerging approach with significant potential for the monitoring and assessment of freshwater ecosystems globally.
“I hope that this work will inspire other freshwater ecologists working in the tropics to drop in a hydrophone. There is so much left to learn,” says Gottesman.
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Microplastic fragments. Image: Wolfram Burner | Flickr Creative Commons
Plastic pollution is increasingly recognised as a major global environmental challenge, particularly in the world’s oceans. However, recent evidence shows that plastics are increasingly present in freshwater river systems, not only affecting the health and status of aquatic life, but also providing another source of plastics to marine environments.
A global initiative called the 100 Plastic Rivers Project investigates how plastics are transported and transformed in rivers and how they accumulate in river and estuary sediments, where they can leave a long-lasting pollution legacy.
The project has been working with scientists in more than 60 locations across the world to sample water and sediment in rivers for both primary microplastics (such as cosmetic microbeads) and secondary microplastics (from larger plastic items which have broken down, or clothing fibres).
By assessing freshwater and oceanic systems as interlinked, the aim of the project is to better understand how we might manage the global plastic crisis. 100 Plastic Rivers Project researchers suggest that our ability to assess global risks from microplastic impacts on environmental and public health is limited by a lack of knowledge of their transport, deposition and uptake through aquatic ecosystems. A key question here concerns the toxicological effects microplastics can have on aquatic food webs.
Project lead Professor Stefan Krause, of the School of Geography, Earth and Environmental Sciences at the University of Birmingham, UK, explains, “Even if we all stopped using plastic right now, there would still be decades, if not centuries-worth of plastics being washed down rivers and into our seas.
We’re getting more and more aware of the problems this is causing in our oceans, but we are now only starting to look at where these plastics are coming from, and how they’re accumulating in our river systems. We need to understand this before we can really begin to understand the scale of the risk that we’re facing.”
The 100 Plastic Rivers Project aims to provide an overview of the global distribution of microplastics in freshwater ecosystems, using newly-developed standardised sampling protocols and extraction methods. All of the data collected will be GPS and date tagged and uploaded into an open-access database for researchers to use. One of the key advances made by the project – funded by the Leverhulme Trust, the EU Horizon 2020 Framework, the Royal Society and the Clean Seas Odyssey – is a ‘toolkit’ of approaches for assessing microplastic pollution in river systems.
The initial results of the project are being presented this week at the General Assembly of the European Geosciences Union (EGU), in Vienna, Austria. They show a huge diversity in the types and sources of plastic found in selected river estuaries in the UK and France.
In a recent pilot study, the 100 Plastic Rivers team at the University of Birmingham collaborated with the Clean Seas Odyssey citizen science project to ‘field-test’ their sampling methods. Working with members of the public in river estuaries around the UK and France coast, the team gained an insight into the different types of microplastic accumulating in estuary sediment. This initial picture suggests that even in countries bound by strict EU water pollution policies, there are numerous sources of plastic contributing to high concentrations of microplastics in river systems.
The project is looking for more partners, so if you are currently working on microplastics or already work in a freshwater system and can collect sediment and water samples, the 100 Plastic Rivers team can send you a sample kit and standardised protocol. Samples can then be sent back to the University of Birmingham for analysis. We will follow the progress of the 100 Plastic Rivers Project, and report back on the findings of their important work in the future.
To meet the world’s growing water needs, we need to squeeze the most out of every drop, which means seeing wastewater as a valuable resource. Image Credit – Danilo Pinzon / World Bank (CC BY-NC-ND 2.0)
Re-published from our partners at Horizon: the EU Research & Innovation magazine.
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Currently, water use risks leaving half the world facing severe scarcity by 2030 as demand outstrips supply. The linear way our societies and industries think about water – constantly extracting it for use and then dumping it back into oceans and rivers – is unsustainable in a world facing the challenges of a growing population and climate change.
“Natural water resources are not endless,” says Dr Christos Makropoulos, Associate Professor at the National Technical University of Athens, Greece, and the Chief Information Officer of KWR, a water research institute in the Netherlands. “They are very dependent on a stable climate, which is currently changing – and we’ve based our entire economy and livelihoods on them just being available whenever we need them.”
The United Nations believes there could be enough water to meet the world’s growing needs, but only if we find a better way to make the most of every drop. One way to do this is to think about water in terms of the circular economy – keeping water within social or industrial systems for as long as possible and simultaneously extracting additional value from it.
“If you manage to treat and reuse wastewater, and extract useful materials and energy, like nutrients that could become fertilisers for agriculture, or added-value compounds for the chemical industry – you are both protecting the environment and shielding your cities and industries from water scarcity,” says Dr Makropoulos.
In the Netherlands, researchers are re-using wastewater from a brewery by treating it through an engineered ecosystem. Image credit – Christos Makropoulos
Water mining
He is the co-coordinator of NextGen, a project demonstrating different circular water technologies across ten different sites in Europe. In the Netherlands they are using engineered ecosystems to treat and reuse wastewater from a brewery. In the United Kingdom, they are developing technologies to extract methane gas from wastewater treatment plants so that it can be used as an energy source.
They even have a portable wastewater mining unit in Greece that extracts sewage, cleans it using tiny membranes, disinfects it and then irrigates public parks.
The technologies at all ten sites use water in ways that reduce the amount that needs to be extracted and therefore enhances regional resilience against water scarcity. Most of these solutions were developed prior to NextGen’s inception, but the project is helping to refine and advance the technology while also showcasing their potential on a bigger, more commercial stage.
“In each site we demonstrate a different set up that closes the cycle in terms of energy, water or resources, or sometimes a combination of all three,” says Dr Makropoulos. “Part of the ambition here is to use these sites as living labs, in other words as spaces where people – like schools, regional authorities or municipalities, or businesses – can visit and understand how they work.”
This is a crucial step in convincing local governments and businesses to change how they think about water – that it is a renewable resource rather than a commodity to be exploited. In the past, circular technologies struggled to scale up because regulators and the market did not appreciate their potential and failed to create the commercial environment needed to drive demand.
These ‘living labs’ are also a tool to help regulators see the need to change legislation, added Dr Makropoulos. Outdated definitions and regulations of waste are currently standing in the way of some resources extracted from wastewater entering the market or becoming cost-competitive.
According to Ilaria Schiavi, a resource management expert at IRIS, an Italian sustainable technology business, many European countries struggle to grasp how the circular economy works in practice.
“Not many countries have circular economy strategies and the ones that do are still figuring out how actions can trickle down to planning on the ground,” she says.
This could mean that opportunities to create systems that reduce a region’s water demand are missed in major development projects, which can lock areas into the current use-and-discard water culture.
“The approach to water has been that it will always be there and we don’t need to think about it when enlarging a city,” says Schiavi, who is also the project coordinator of Project Ô, which aims to demonstrate different technologies and approaches to circular water management. “But that’s not true anymore.”
Lower bills
The researchers are developing software to help local authorities and businesses analyse and understand the economic benefits of sustainable water strategies, such as the amount of money saved by rewarding those who use less water with lower bills. They are also demonstrating wastewater recycling technologies that ease the pressure on existing sewage treatment sites alongside strategies for using alternative sources of local water, like rain or from industrial sources.
Water stress happens when demand for water exceeds the amount available of acceptable quality, and varies from region to region. Image credit – Horizon
Most existing water treatment plants were built to deal with domestic sewage, but with growing pollutants from nearby industry and changing habits in society, like the increased use of antibiotics, plants now have to cope with contaminants that they were not initially designed for. This cocktail of pollutants makes it more expensive to clean the water, but also harder to extract any resources that could be reused.
“We are trying to act on the contaminants close to the source of the contamination because they are concentrated enough to be effectively treated,” says Schiavi.
The project team has already helped install a treatment plant at an Israeli aquaculture research centre that would enable 100% recycling of the water, thus eliminating the need to take more out of the ocean.
The plant uses algae to treat the wastewater, which pulls nutrients out and these are then used for feeding locally farmed fish or as a feedstock for nutraceutical (dietary supplements) or other industrial applications. This circular approach also prevents the wastewater being dumped back into the environment, where it can trigger huge blooms of toxic algae that can suffocate other marine life.
“The best way to prevent waste is not to generate it, and that’s the same approach we want to create with wastewater,” said Schiavi.
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This post Mining sewage for fertilisers and energy to prevent water shortages was originally published on Horizon: the EU Research & Innovation magazine | European Commission.
Insect declines in Germany: can insect-friendly farming practices help reverse the trend?
A dragonfly holds tight to vegetation in strong wind. Dragonfly populations are declining across Europe. Image: Jean François Bonachera | Flickr Creative Commons
Insect conservation is currently a hot topic in Germany. A succession of scientific studies have documented insect population declines across species and habitats in recent years, a trend which is gaining increasing public and political attention. As is the case with global concerns over insect declines, the big question is: what can be done to reverse these negative trends?
Scientists document insect declines across Germany
A 2017 study found that flying insect biomass in Germany has dropped by 76% over the last 27 years. Researchers collected flying insects across different habitats within protected areas in lowland western Germany using mesh tent traps. They noticed a steep decline in insect biomass (the total weight of insects caught) in recent years, particularly around midsummer, where biomass has dropped by 82%. Writing in the journal PLOS ONE, Caspar Hallmann and colleagues attribute the declines (in part) to agricultural intensification, particularly intensive fertiliser and pesticide use, and habitat loss. Another PLOS ONE study in 2013 documented how the leaching of neonicotinoids (a common agricultural insecticide, linked to insect declines globally) led to significant declines in aquatic insect abundance. Many flying insects (such as dragonflies and damselflies) have significant aquatic phases in their life cycles, and water pollution is thus a key stressor on wider insect populations.
Another German study found that light pollution can be a cause of insect declines. Scientists from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) suggest that climate change, pesticides and land use changes alone cannot fully explain the decline in insect populations in Germany. “Half of all insect species are nocturnal. As such, they depend on darkness and natural light from the moon and stars for orientation and movement or to escape from predators, and to go about their nightly tasks of seeking food and reproducing,” explains Dr. Maja Grubisic, lead author of the 2018 study in Annals of Applied Biology. “An artificially lit night disturbs this natural behaviour – and has a negative impact on their chances of survival.” The researchers identify light pollution as an emerging stressor for insect populations, particularly in agricultural landscapes. They argue that light pollution should thus be considered as part of environmental conservation approaches designed to protect insect populations.
Earlier this month, a study found that over half of the c.500 wild bee species found in Germany are at risk of extinction, or already locally extinct – a trend driven by intensive agricultural practices. Researchers from the Ludwig-Maximilians-Universitaet (LMU) found that bee species which emerge in late summer struggle to find sufficient food in intensive agricultural landscapes. “According to our analysis, late-emerging species – Melitta tricincta, for instance – are increasingly at risk in agricultural areas, because they can no longer find sufficient food,” says Prof. Susanne Renner, lead author of the study. “In regions where the land is intensively farmed, the fields are virtually devoid of flowers at that time of the year. Bees that emerge in the spring can at least count on the availability of plants such as oilseed rape and the presence of blooming orchards.”
Supporters of the ‘Save the Bees’ campaign in Bavaria, Germany. Image: Friends of the Earth
Public and political appetite for positive change
Awareness of such insect declines has reached public and political realms recently. Last month, environmental groups behind the ‘Save the Bees’ campaign in Bavaria, southern Germany secured the signatures of around 1.75 million people (nearly 20% of eligible Bavarian voters) in a petition to radically improve the environmental impacts of farming methods in the state. The petition asks that 20% of land is made ‘bee-friendly’ by 2025, and 30% by 2030. This shift could be made possible by a shift to more organic farming approaches, campaigners suggest. The petition states that 10% of green spaces in Bavaria should be turned into insect-friendly flowering meadows, and that rivers and streams should be buffered from pesticides and fertilisers through the protection of riparian strips of natural vegetation along their banks.
The ‘Save the Bees’ campaign – which involved a series of high-profile, carnival-like protests in the run-up to the petition deadline – is designed to change and strengthen the existing Bavarian Nature Conservation Act. But the ‘Save the Bees’ campaign is not just about bees. Last month, Agnes Becker, the leader of the Bavarian Ecological Democratic Party (ÖDP), which backed the petition, told a television debate, “It’s not so much about the honey bee as it is about a very long and ever-growing list of threatened species of animals and plants, but the bee is our mascot, our symbol.”
The referendum result has prompted a series of round-table meetings between the environmental groups behind the petition, and the Bavarian Farmers Association which contests some of the proposed measures. The Association argues that the petition’s demands of de-intensified farming methods are restrictive and unworkable. The latest round-table, held last week, prompted four working groups – ‘agricultural landscapes’, ‘forest’, ‘waters’ and ‘settlements/urban areas’ – to be established whilst the state parliament decides whether to enforce the petition demands in law.
Meanwhile, the Social Democrat (SPD) Minister for the Environment Svenja Schulze has proposed an ‘action plan for insect protection’ across the whole of Germany. The action plan, which was originally proposed to the German cabinet in October 2018, is under consultation, and could mobilise €100 million of funding each year for insect conservation in Germany. Schulze says, “Stopping the decline of insects is a key political task of our time.” Depending on the progression of negotiations, the action plan could be adopted by the government as early as next month.
Bees are important pollinators of flowers and crops. Image: BrambleJungle | Flickr Creative Commons
Could ‘insect-friendly’ agriculture halt insect population declines?
What these scientific findings and political debates have in common is a concern with making German agricultural practices more ‘insect-friendly’. Insects, of course, provide important ecosystem services, particularly pollination, in many agricultural landscapes. The German Association for Environmental Protection and Conservation (BUND) estimates that the economic value of the pollination services provided annually by insects in Europe is more than 14 billion euros.
A key question, then, is how to balance insect conservation (and that of biodiversity more widely) with the economic and food security concerns of modern agricultural production? Are shifts to lower-intensity, organic-led farming approaches – as advocated by the ’Save the Bees’ campaign – realistic in practice?
A recent policy report from the Ten Years For Agroecology (TYFA) project suggests that they might – but that such a shift requires significant changes to public eating habits. Published in September 2018, the TYFA report uses computer modelling to explore the possibilities of ana Europe ‘agro-ecological’ food system for 2050. An agro-ecological system is based on “abandoning pesticides and synthetic fertilisers and redeploying extensive grasslands and landscape infrastructures,” in order to protect biodiversity and mitigate climate change effects, whilst still providing sustainable food sources for European populations.
Authors Xavier Poux and Pierre-Marie Aubert report that whilst such agro-ecological measures would likely lead to a decline in agricultural production of around 35% across Europe, this would not be an issue if public eating habits shifted away from meat towards plant-based diets. They suggest that whilst such a scenario represents a ‘utopia’, their study shows that it is possible to reduce agricultural carbon footprints and restore healthy natural environments, whilst feeding European people healthily. In other words, whilst their vision is unlikely to be played out in practice, perhaps alternative approaches to European agricultural practices are realistic, if there is sufficient public and political will.
Sympetrum dragonfly in flight: aquatic ecosystems are important for many flying insect populations. Image: Artur Rydzewski | Flickr Creative Commons
The wider landscape: what about aquatic environments?
What do these issues and debates have to do with aquatic environments? In short: a lot. As noted before, many flying insects have significant aquatic stages (e.g. as larvae), and often require high water quality to successfully hatch. More broadly, terrestrial and aquatic environments are inherently linked across wider landscapes, and biodiversity losses on land are often accompanied by parallel losses in water, which can happen at a great rate and magnitude. The EU MARS project found that the impacts of intensive agriculture – pollution, habitat loss and fragmentation, water abstraction – can are often some of the most important stressors on aquatic ecosystems.
As aquatic scientist Dr Sebastian Birk from the University of Duisburg-Essen puts it, “The bigger issue is ‘how do we want to live in the future’?’ Insect declines and aquatic ecosystem degradation are just indicators of how we treat our natural environments. Ultimately, pollutants often end up in the gutter, and then our rivers and lakes. So what you do on the land will affect the waters, too.”
We will continue to follow the developments in Germany and report back over the coming months.
What does the future hold for European rivers and lakes?
Lake Beyşehir, one of the study locations for future environmental storylines in the study. Image: Pixabay | Creative Commons
Can we predict what the future holds for European rivers and lakes? How might changes to socio-economic conditions alter future trajectories for the health and status of surface waters across the continent? These are the questions at the centre of a new study led by Leoni Mack, from the University of Duisburg-Essen in Germany.
Funded by the EU MARS project, Mack and colleagues developed computer models to project how European surface waters are likely be impacted by different climatic, land use, management and development trends in the future. Their results suggest that stronger environmental policy and management are needed to achieve good ecological status in European surface waters under future conditions.
However, if such measures are not implemented, the linked pressures of human activity and climate change are likely to cause ongoing reductions in ecological status across the continent. Their results suggest that the impacts of pressures across Europe are likely to be more severe in rivers than lakes.
Key pressures in the future are likely to be similar to today: nutrient inputs from agriculture, land use changes (e.g. riparian zone development), poorly managed water abstraction, and growing climate change effects (e.g. water temperature increases; changes to flood and drought patterns).
There is likely to be geographical variation in how these pressures affect freshwaters, the study suggests. In Continental and Atlantic regions of Europe, land use changes are likely to be the key driver of environmental pressures, whilst in Mediterranean regions, the effects of climate change are predicted to dominate. In more northerly Boreal regions, the combined impacts of land use and climate change are predicted to drive environmental pressures, reflecting a likely trend of agricultural activities shifting northward with a warming climate.
Graphical abstract of the study showing: methods, map of study basins, and results (TN= nitrogen, TP = phosphorous, Chl-a= algae growth). Image: Mack et al 2019.
Three lake and four river basins were modelled in the study, representing a number of typical European environmental conditions and human pressures. Nitrogen, phosphorous and chlorophyll a (a proxy for algae growth) dynamics were modelled to two time horizons – 2030 and 2060. These dates were chosen to give a picture of how alterations to current environmental policy (e.g. the Water Framework Directive) could have short-term impacts in the next decade (2030), and how climate change effects might be experienced over a longer term (2060).
Three storylines describing land use, management and development were assessed: ‘Consensus’, ‘Techno’, and ‘Fragmented’. Each storyline describes possible political, economic and cultural trends which to different combinations of drivers and pressures across Europe, using Shared Socio-Economic Pathway projections of socio-economic trends and IPCC Representative Concentration Pathway projections of climate change. The storylines are thus broad-brush forecasts of possible future trends across the continent, developed to help guide environmental policy and management decisions.
In Consensus World, future development in Europe follows similar patterns to the recent past, and environmental conservation and policy is supported. The world tends towards being relatively politically stable (Shared Socio-Economic Pathway 2), alongside a stablising and relatively low level of climatic change (Representative Concentration Pathway 4.5).
In Techno World, economic growth is strong, led by technological innovation, and human resource consumption is high. Ecosystems are valued largely for the benefits they provide to humans, and environmental protections are gradually rolled back over time in favour of promoting economic growth. High greenhouse gas emissions and rising global temperatures (Representative Concentration Pathway 8.5) are present, and there is a strong, carbon-based global economy (Shared Socio-Economic Pathway 5).
Fragmented World envisions a future with rising carbon emissions and significant climatic change (Representative Concentration Pathway 8.5). Technological developments are slow, and fossil fuel dependence is high; international cooperation is poor and significant pockets of poverty persist (Shared Socio-Economic Pathway 3). There is poor trans-national co-operation on environmental protections. Current environmental policy commitments are not met, or rolled back over time.
The authors highlight that different management approaches could have positive ecological impacts in each storyline. In Consensus World, present-day measures such as riparian shading had a positive impact on ecological status, whilst in Techno World, technological improvements such as increasing wastewater treatment efficiency were predicted to be key. In Fragmented World, agricultural extensification (i.e. the reduction in fertilisers and pesticide use per land area) was highlighted as a means of reducing nutrient pollution and habitat change.
The study, published in Science of the Total Environment, is rich in detail of how these potential political, economic, climatic and environmental trajectories might interact with freshwater ecosystems in the future. Overall, the results highlight the need for continued high ambitions for freshwater policy and management, and the political and public will to implement it for decades to come. The study emphasises the need for locally-appropriate targeted freshwater management measures to mitigate the effects of environmental pressures, whichever storyline(s) might develop in the future.
The Freshwater Blog 
