Urban rivers across Europe are subject to multiple stresses linked to the surrounding built environment, particularly pollution, fragmentation, barriers and habitat modification. However, increased focus on the many benefits of urban nature, coupled with the imperatives in the EU Water Framework Directive to improve such ‘heavily modified water bodies’ to ‘good ecological potential’ mean that urban river restoration projects are proliferating.
The rivers Brun and Calder meet in the town of Burnley, in North-West England, and are part of the wider Ribble catchment. Flowing through an urban landscape which has supported industrial activity for centuries, the Brun and Calder have both been heavily modified and impacted by humans. Long stretches of the rivers are enclosed by stone and concrete channels, and in some places the river beds are made up of the same cobblestones found paving old streets through the town.
A new video (which you can watch above) produced by The Ribble Rivers Trust documents the community-engaged habitat restoration of Burnley’s rivers undertaken through the Urban River Enhancement Scheme (URES).
The Ribble Rivers Trust is an environmental charity established in 1998 to protect and restore the rivers, streams and watercourses within the Ribble catchment and to raise public awareness of the value of local rivers and streams. The Trust was awarded over £600,000 by the Heritage Lottery Fund in 2013 to deliver the URES, which intends to improve the habitat quality and biodiversity of Burnley’s rivers, whilst engaging local communities through education and conservation programmes.
The video shows URES habitat improvement on Burnley’s rivers, removing litter and debris, uprooting invasive species such as Himalayan balsam, constructing fish passes on large weirs, and restructuring river beds to create semi-natural riffles and pools in place of the existing sewer-like channels. It shows the various ways in which local communities are consulted and engaged in this process, through school visits, environmental artworks and conservation action days.
Below is a podcast interview with MARS scientist Prof Steve Ormerod from Cardiff University, carried out on the banks of the River Brun. Steve – a Burnley native – gives us an insight into the ways in which urban nature, culture and heritage are entwined along the banks of Burnley’s rivers, and how such recent restoration projects have significantly improved their habitat quality and biodiversity.
Since the podcast was recorded, salmon parr have been found upstream of the town, an extremely encouraging sign that migratory salmon can now successfully navigate Burnley’s rivers to reach a wide area of upstream spawning grounds.
Caddisflies are found in freshwaters across Europe, with their larvae well-known for their remarkable ability to build cases from organic materials such as vegetation, sand and silt (which can take on beautiful creative forms). In Britain alone, there are around 200 different caddisfly species, making them one of the most diverse groups of pond animals.
New research by a team of ecologists from the UK, Germany and Malaysia has shown how caddisflies are not only resourceful ‘house builders’, but also productive ‘gardeners’ of their habitats. Writing in Freshwater Biology, the researchers, led by Nicola Ings, describe how caddisflies actively encourage food growth in their local environment, through ‘weeding’ and ‘fertilisation’.
The organic cases that caddisfly larvae build are known as galleries, held together with silk and fixed to a stream or lake bed. The team of researchers used samples of galleries built by a common caddisfly species, Tinodes waeneri, from five lakes in the Lake District. Their aim was to study whether gallery biofilms contained algae communities distinct from the biofilm on the surrounding lake bed (known as the epilithon), and if so, whether these algae ‘gardens’ were found across a range of lakes with different ecological productivity.
The researchers found that across all five studied lakes, caddisfly larva galleries had a greater content of diatom pigments, including fucoxanthin, as well as a distinct assemblage of diatoms. This abundance of diatoms – a rich food source for caddisfly larvae – on the galleries is the result of active ‘gardening’ by the larvae of their micro-habitat.
Caddisfly larvae live in their galleries (which can reach several centimetres in length), and graze algae around the gallery mouth. This ‘weeding’ helps prevent the gallery from becoming overgrown with filamentous green algae which can inhibit the growth of diatom-rich biofilm. The rear end of the gallery casing (where the biofilm fertilised by nutrient-rich excretions often grows) is gradually ingested by the larva, and the structure slowly extended forward with fresh silk and particles at the front.
This active modification of the caddisfly larva’s immediate environment has a number of benefits for the organism. The new silken material added to the front of the gallery casings creates new surfaces on which biofilm (on which they graze) can grow. At the same time, the older parts of the galleries are typically covered in biofilm rich in diatoms are harvested. In effect, the caddisfly larvae galleries undergo a slow migration across a lake or stream bed, creating new micro-habitats for algae growth at their head, which will be eventually harvested at the rear.
‘Gardening’ gives a key advantage to caddisfly larvae by widening the range of potential habitat conditions in which they can survive. The researchers speculate that nutrients will be more tightly retained in lake beds dominated by such sedentary, gardening insect larvae, compared with those dominated by more mobile collector grazers. As a result, the nutrients retained by ‘gardened’ larvae galleries may then be exported to the land when the adult caddisflies emerge.
The study gives a fascinating insight into the ability of microorganisms to actively modify their immediate environment to improve their life chances. It would be fair to say that caddisfly larvae may well be the smallest (and most resourceful) of all the water gardeners.
Freshwater ecosystems around the world are increasingly threatened by multiple stressors: the combined impacts of pollution, water abstraction, invasions, fragmentation, climate warming and so on. However, at present, scientific knowledge on the interactions and impacts of different stressor combinations across ecosystems remains incomplete.
A new study conducted at the University of Leeds, UK, gives new insights into how simultaneous biological invasions and climate warming may affect freshwater ecosystem functioning. The team, led by Daniel Kenna, used laboratory experiments to study how changes in water temperature affected the rate at which two tiny freshwater crustaceans (one native to the UK, and the other an invasive) processed leaf-litter debris, which is an important source of nutrients commonly found on the bed of rivers and lakes.
Biological invasions are a common stressor in freshwater ecosystems across the world, as non-native species are either introduced by humans, or find their way into ecosystems made newly habitable by environmental change. Invasive species may out-compete native species for food and habitat, or carry harmful diseases (e.g. the signal crayfish in Europe). As a result, an influx of invasive species into a freshwater ecosystem may significantly alter its biodiversity, health and functioning.
Writing in Oecologia, the University of Leeds team describe their experiment involving two micro-crustaceans: Gammarus pulex, an amphipod native to the UK; and the so-called ‘killer shrimp’, Dikerogammarus villosus, a fast growing and comparatively large amphipod which is native to Eastern Europe, but increasingly invasive across the western continent.
When matched for size, the team found that the UK native Gammarus was more efficient than the ‘killer shrimp’ at leaf-litter processing. The invasive amphipod preferred warmer water temperatures, suggesting that invasions which displace the native Gammarus under climate warming, may lead to a reduction in leaf-litter processing, and so a decline in ecosystem functioning.
However, the ‘killer shrimp’ is a larger animal (around 30mm to Gammarus’s ~20mm), and large individuals can process leaf litter at a faster rate than smaller ones of comparable size to the native species. In addition, ‘killer shrimp’ processing rates increased at a faster rate in response to increasing water temperatures than those of Gammarus individuals of a similar size.
This means that any decreases in ecosystem functioning caused by the displacement of Gammarus populations by ‘killer shrimp’ invasions may be offset by increases in leaf-litter processing in the invasive species where water temperatures are increased.
As such, the study gives a novel insight into an antagonistic relationship between multiple stressors: where some of the potentially harmful effects of the invasive species (i.e. reduced ecosystem functioning) are largely mitigated by the effects of climate warming.
Kenna, D., Fincham, W.N.W., Dunn, A.M. et al. (2016) Antagonistic effects of biological invasion and environmental warming on detritus processing in freshwater ecosystems. Oecologia doi:10.1007/s00442-016-3796-x (Open access)
We thought we’d start the new year with an inspiring video. Dr Kurt Fausch, a stream ecologist and professor at Colorado State University, has recently published a book, For the Love of Rivers, which draws readers into an international collaboration among freshwater ecologists to discover the hidden connections between rivers and their surrounding forests.
In the video above, Fausch provides a poetic and persuasive case for why rivers are so important, for humans and non-humans alike. He says, “Like trees and music and good health, streams and rivers are a gift to us as humans… In the end, I believe we will need to understand how and why we love rivers, if we hope to conserve them.”
Dr Fausch’s career in freshwater ecology has generated many novel and influential contributions to our understanding of habitat use by freshwater fishes, individual fish movement, and the landscape ecology of riverine fishes. His 2002 BioScience paper ‘Landscapes to Riverscapes’ (pdf) outlined a new approach for management and conservation of stream fishes, describing the scale at which ecological studies and restoration activities can be most effectively accomplished. Fausch recently received the Award of Excellence from the American Fisheries Society (AFS) at its 2016 Annual Meeting in Kansas City, Missouri.
The For the Love of Rivers book follows Fausch’s previous art-science communication project, RiverWebs, a feature-length film by Freshwaters Illustrated about the life and work of Dr. ShigeruNakano to explore how streams and forests depend on each other. After Nakano’s tragic death, Fausch and colleagues collaborated to follow the path along Japanese watersheds forged by Nakano and discover deeper truths about the critical roles that streams play in the wider landscape.
Find out more about the For the Love of Rivers project and the RiverWebs film here.
As the end of the year approaches, we’re looking back over 2016 to collect 16 of our most popular posts on aquatic lives.
It’s been a fascinating year to write about freshwater science, policy and conservation. New scientific research is shedding light on the complex nature of freshwater ecosystem responses to multiple pressures, whilst policy and management initiatives attempt to deal with the implications of an increasingly interconnected and stressed world on freshwater biodiversity and functioning.
It’s been the most successful year yet for the Freshwater Blog, with record numbers of visitors. Thanks, as ever, for reading. You can keep up to date with our posts, and add your voice to the debate through our Twitter, Facebook and LinkedIn pages. Happy 2017!
A boom in construction of major hydroelectric dam projects on the Amazon, Congo and Mekong rivers increasingly threatens a range of rare and unique freshwater biodiversity according to a new study published in Science.
Existing dams on the three basins are generally small and located in upland tributaries, but over 450 additional major dams are planned, with some already under construction. Most of these dams are planned to be built in areas of fast water flow – such as waterfalls and rapids – which are often hotspots of high biodiversity (read more).
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 (read more).
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.
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.
What advice would I give to a new generation of freshwater scientists? (read more).
In March, 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.
In April, a group of around 60 river basin managers, Water Framework Directive officials, European Environment Agency representatives, external experts and MARS aquatic scientists met in Vienna to discuss the key challenges for freshwater management and policy across Europe.
Central to the two days of discussions was the challenge of multiple pressures: the often unpredictable interactions between individual pressures on freshwaters, such as pollution, floods, droughts and river bank alterations. Despite growing awareness of the importance of multiple pressures, their joint impacts on aquatic ecosystems are not well understood, and as a result they are poorly reflected in existing River Basin Management Plans – the framework through which the Water Framework Directive is implemented in Europe.
There was rich science-management dialogue at the meeting, titled ‘Multiple Pressures in River Basin Management‘, which took place at the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management – a MARS partner. The MARS project is just past its halfway point, and the meeting gave the opportunity for water managers and policy makers to help shape the project’s research and outputs to ensure they are relevant and useful in practice (read more).
We live in a world that never stays still. People and places are ever more globally interconnected, dynamic and developing. Technological innovations feed into new cycles of use, waste and pollution. Ecosystems flux over time and space through invasions and introductions, novel assemblages and emergent patterns.
Circling all of this, scientific consensus predicts an increasingly variable and warming climate in the century to come. An age that could well be ratified later this year as a new geological epoch, fundamentally shaped by human activity and known as the Anthropocene.
How can environmental policy makers deal with such complexity and dynamism in a world they seek to positively influence? How can environmental policies anticipate the changes of uncertain future worlds? And what research programs, early warning systems and governance structures are needed to make such ‘anticipatory policy making’ a reality?
A new Science for Environmental Policy ‘Future Brief’ addresses these questions by examining a range of tools and approaches that can be used to identify emerging environmental risks. The approaches examined include strategic foresight tools, scanning of the internet for information, citizen science and state-of-the-art monitoring technologies (read more).
Rewilding is a concept that has increasingly captured the attention of environmentalists and the public across the world. Broadly put, rewilding projects attempt to restore natural ecological processes in degraded ecosystems, and often to reintroduce flora and fauna that has become locally extinct.
A new policy brief produced by Rewilding Europe and Paul Jepson from Oxford University School of Geography and the Environment argues that rewilding approaches can reinvigorate European environmental policy, and extend and improve existing restoration approaches. In ‘Making Space for Rewilding: Creating an enabling policy environment‘, the authors frame rewilding as a ‘logical next step’ for the development of EU policy, and suggest how policy spaces for rewilding might be encouraged in the future.
Paul Jepson explains, “We need new concepts and innovation in policy for nature conservation to regain ground. Rewilding presents an opportunity to shift gear from protection to restoration, upgrading ecosystems, improving network connectivity and creating new value for people” (read more)
On 23rd June, British voters will decide on the future of the United Kingdom’s membership of the European Union. The EU is an economic and political partnership of 28 countries (or member states) which was formed after the Second World War. The UK joined the then-European Community in 1973. The EU provides a ‘single market’ for people, goods and capital to move easily between member states, and sets rules and standards across a wide range of areas including industry, commerce and environmental management. By far the biggest EU expenditure is on agriculture, so the environment is, de facto, at the heart of the Union.
We report on the potential environmental impacts of a Leave vote (which was the eventual result), specifically for freshwater ecosystems (read more).
In May, we published an article on rewilding and environmental policy, asking the question: what might rewilding ‘do’ for degraded freshwater ecosystems that widespread and established restoration projects aren’t doing already?
Paul Jepson from Oxford University School of Geography and the Environment, author of the new rewilding policy brief with Rewilding Europe, responds to this question, describing a positive rewilding approach for freshwater management (read more).
‘You broke it, you own it.’ That was political ecologist Paul Robbins’ take on the results of a new experimental trial (open-access) at the University of Alberta, Canada where adding iron to eutrophic lakes was found to help manage outbreaks of harmful algal blooms. For Robbins (and others, such as the Ecomodernist movement), the damage humans have caused to the natural world means there is a pressing need for radical and often-interventionist management to reverse decades of ecological harm.
The University of Alberta experiments suggest that one way to positively ‘own‘ damaged freshwater ecosystems is through geo-engineering, the deliberate large-scale intervention in the Earth’s natural systems to counteract environmental damage (most often climate change).
Freshwaters comprise some of the most highly altered and modified ecosystems in the world: new concrete geologies and diluted chemical flows. In this context, a new special issue of the journal Water Research brings together 60 scientists from across the world to present findings on the effectiveness of geo-engineering approaches in managing the harmful effects of phosphorous pollution in freshwaters (read more).
Protected areas are one of the key conservation tools used by environmental managers and policy makers across the world to help protect biodiversity and ecosystems. Protected areas (for example Sites of Special Scientific Interest in the UK) set aside blocks of land and water in which human activities – such as fishing, farming, hunting and building – are limited as a means of promoting the survival of often rare and valuable species and ecosystems.
Freshwater protected areas face a growing set of challenges, not least to protect biodiversity and ecosystems that are open to change and move, under increasing global human demands for water. Addressing these challenges, a recent special issue of Aquatic Conservation: Marine and Freshwater Ecosystems compiles a set of articles examining the aims and effectiveness of freshwater protected areas globally (read more).
It’s a common lament to hear from freshwater conservationists: if only our rivers and lakes had better legal protection in response to the many pressures they face. In New Zealand, a new piece of environmental legislation is intended to do just that, by taking the unprecedented step of granting a river the legal rights of a citizen.
The Whanganui River legislation, called the Te Awa Tupua bill, is currently moving through parliament. If passed (which appears very likely), the bill would grant the river ‘legal personhood’, that is the right for the Whanganui tribe to speak for the river in the country’s courts, and to file lawsuits on its behalf when environmental protections are not upheld. This approach could be seen as a type of co-management, through which the rights of the river, and its health and diversity, are upheld through shared decision-making involving local Maori tribes (read more).
Dialogues between environmental scientists and policy makers form key cogs in modern conservation and restoration practices. Scientific research can inform and support ‘evidence-based’ policy making, whilst policy makers will often prioritise and fund socially and environmentally pertinent research topics.
The multiple ways in which aquatic ecosystems support and shape human lives makes productive science-policy dialogues about their management and protection particularly important. There is a pressing need for science-policy dialogues to help form adaptive policy and management responses to such new ‘natures’, to try to build in ecosystem resilience to emerging treats to climate change and to conserve highly-pressurised biodiversity.
In this context, a new opinion piece by Steve Ormerod from Cardiff University and G. Carleton Ray from the University of Virginia argues that aquatic scientists can play a pivotal role in identifying gaps, failings and emerging trends for policy and regulatory practices. Writing in Aquatic Conservation Marine and Freshwater Ecosystems, the authors identify the concept of resilience as an organising principle for science-policy responses to emerging human pressures. Promoting environmental resilience provides a means of bringing new ecological concepts, the importance of an ‘ecosystem approach’, and the value of ecosystem services and natural capital further into policy making (read more).
Freshwater species populations dropped by 81% globally between 1970 and 2012, according to a new World Wildlife Fund report released today. According to the Living Planet Report 2016, this freshwater species decline is more than double that observed in land (38%) and marine (36%) populations, and population declines are predicted to continue in years to come.
Habitat loss is the major cause of declining freshwater species populations, as lakes, rivers and wetlands across the world continue to be abstracted, fragmented, polluted and damaged. As ongoing research into multiple stressors tells us, freshwater habitat loss can be caused by numerous pressures caused by human activities throughout entire catchments and river basins. Over-exploitation is another key cause of species loss, as fish and bird populations are harvested for food, and reptiles and amphibians collected for the pet trade (read more).
The MARS Project has been undertaking scientific research into the effects of multiple stressors on aquatic environments for nearly three years now, and project scientists are beginning to widely publish their findings.
Six new papers involving MARS research have recently been published online in the journal Science of the Total Environment, some of which are currently available for free through open-access publishing (read more).
Conservation efforts to maintain and restore riparian zones along many global rivers are often inadequate, according to a new study. Writing in the journal Biological Conservation, Eduardo González and colleagues draw on a body of emerging research on riparian zones to identify a range of ecological, socio-economic and policy pressures for their fragmented distributions.
Riparian zones are the ecosystems found along the banks of rivers and streams: narrow transitional zones between land and water, often with diverse ecosystems that play important roles in the ecological functioning of the wider landscape. Riparian zones – often dominated by tree and plant species which thrive in damp conditions – can help buffer diffuse pollution, mitigate flood risks, store carbon, reduce bank erosion, provide shaded and cool stream water, prevent livestock from trampling fish spawning grounds, and offer valuable biodiversity habitat (read more).
A very happy new year from all of us at the Freshwater Blog! Thanks for reading, and all the best for 2017.