Bioassessment programs monitor the different plants and animals in ecological communities as a means of understanding the health of an ecosystem and how it might respond to changing environmental conditions over time. A journal article “Is DNA Barcoding Actually Cheaper and Faster than Traditional Morphological Methods?” published in PLOS ONE by researchers in California and Canada examines whether DNA ‘barcoding’ technology – where a species is identified by DNA in tissue samples – is more effective, affordable and quicker than traditional visual, morphological techniques. As also shown in last week’s post about the potential of drone sensing of freshwaters, ecologists around the world are currently assessing the promise of new technology for monitoring, understanding and protecting freshwater ecosystems.
The article, published in April by Eric Stein and colleagues, found that bioassessments using DNA barcoding technology currently cost between 1.7 and 3.4 times as much as traditional, morphological (i.e. visual assessments of a species’ structure and form) methods. However, DNA barcoding approaches can process samples much quicker and at a higher resolution than traditional morphological techniques, potentially helping rapid, adaptive management of environmental issues. After identifying a large global market for bioassessment technologies – particularly in governmental monitoring schemes in the USA and Europe – Stein and colleagues suggest that further research and development of DNA barcoding technologies is necessary and warranted, in order to bring costs down and encourage widespread adoption.
Aquatic bioassessments generally focus on particular ‘indicator’ species – often fish and insects – whose presence (or otherwise) gives an indication of the health of the wider ecosystem. Bioassessments are often repeated over time using groups (or ‘assemblages’) of indicator species which are particularly sensitive to changes in water quality – e.g. invertebrates – to study how an ecosystem responds to stressors such as pollution or overfishing. In the USA, bioassessments are used to assess how far different States comply with environmental legislation such as the Clean Water Act.
Stein and colleagues assessed whether bioassessments can be carried out more cheaply and efficiently by using DNA barcoding technology. Currently, bioassessments using morphological techniques require a significant amount of time and resources to allow trained taxonomists to study different ecosystems. As a result, the quality and level of taxonomic resolution (i.e. the detail in which different organisms are studied and categorised) may vary across different regions, depending on the experience and training of available taxonomists. Another drawback of current bioassessment practice is that it may take six months or more for field data to be translated into the biological indices required for environmental management and policy making – a lag which may prevent quick responses to environmental problems.
DNA barcoding identifies animal species by analysing a short strip of their DNA (see, for more information, the Barcode of Life website, this Wikipedia article and this journal article by Hebert et al (2003). Unknown specimens collected in fieldwork can be referenced to a DNA database such as Barcode of Life Data Systems or GenBank. As is often the case with new technologies, it has been suggested that DNA barcoding has the potential to make bioassessment programs more efficient and affordable, by reducing the amount time spent by taxonomists in identifying specimens, and providing quicker results.
Stein and colleagues first compared the time and cost of traditional bioassessment methods with those of DNA barcoding: from initial sampling through to an identification endpoint which could be used for assessing the health of the sampled ecosystem. Twelve field sites were sampled for macroinvertebrates (which are common freshwater indicator species) along the San Gabriel watershed in California, ranging from mountain streams to urban flood control channels. Traditional bioassessment methods were carried out in a labroratory on one sample, whilst the a second set were shipped in two batches to the Canadian Center for DNA Barcoding (CCDB) for DNA barcoding. DNA analyses were carried out both with current Sanger approach for single species, and the ‘next generation’ IonTorrent approach for bulk samples of organisms.
This first strand to the research found that despite the promise of new technologies streamlining monitoring work, bioassessments using DNA barcoding technology currently cost between 1.7 and 3.4 times as much as traditional, morphological methods. However, DNA barcoding approaches can process much quicker than morphological approaches – the paper suggests that DNA approaches can analyse samples 3-4 times faster than traditional techniques. Similarly, DNA barcoding has the potential to analyse samples at a much higher resolution and taxonomic accuracy than traditional morphological techniques – see Stein’s paper in Freshwater Science for more on this – potentially aiding rapid, adaptive management of environmental issues identified by bioassessment.
The second strand to this research was an analysis on the market and demand for bioassessment technologies. In the USA alone, the research found that more than 13 million samples from 19,500 sites are analysed in bioassessments annually, most notably through country-wide federal monitoring programs. Similarly, bioassessments are regularly used by monitoring programs for the Water Framework Directive in Europe and the Assessment of River Health in Australia.
The authors suggest that as DNA barcoding technology continues to advance, the costs involved will drop. They suggest that bulk sampling technology like IonTorrent – where individual organisms don’t have to be picked and sorted from large samples, and instead DNA can be extracted in bulk to produce a list of all species present – has the potential to significantly reduce time and money requirements in the future, given appropriate investment. They conclude that the potential market demand for new, more efficient and streamlined DNA barcoding technologies is large enough – particularly in the USA and Europe – to justify continued research and development with the intention that costs will be reduced enough to encourage widespread adoption.
Developments in unmanned aerial vehicle (UAV) technology are providing new, potentially cost-effective opportunities for ecologists and conservationists to monitor and protect ecosystems, particularly in remote areas. Widely known for their (often debated) use in remote warfare, there is increasing consensus that drones – as UAVs are often known – have the potential to be used for more positive goals, giving new high-tech means of understanding and potentially protecting global environments.
Lian Pin Koh outlined the potential of drones for conservation in a 2013 TED talk, arguing that they provide an affordable means of mapping biodiversity at higher resolution than current satellite remote sensing technologies; and that they are useful for monitoring protected areas for threats such as poaching and deforestation. Three journal articles – by Koh and Serge Wich in 2012, Karen Anderson and Kevin J Gaston in 2013 and Richard Schiffman in 2014 – suggest similar potential.
In 2012, Koh and Wich founded an organisation called Conservation Drones to help bring together available information on the use of drones for remote sensing. As this UNEP article describes, whilst the technology is still developing, there is a huge amount of ongoing public and private investment in UAVs, which is likely to address current limitations such as limited flight time, and to continue to bring production costs down.
As yet, there has been little research on the potential of drone technology for monitoring freshwater ecosystems. However, a new journal article “The potential of remote sensing in ecological status assessment of coloured lakes using aquatic plants“ by MARS scientist Sebastian Birk and Frauke Ecke addresses this shortfall. Their paper explores the potential of drones for monitoring the health of remote Swedish lakes which are heavily coloured by dissolved carbon. Birk and Ecke found that it is possible to assess the ecological health of coloured lake ecosystems by monitoring plant vegetation which is detectable by drones. Their findings have the potential to significantly alter how ecological monitoring in lakes is carried out, particularly in remote and inaccessible areas.
The growth and diversity of aquatic plants is an important indicator for understanding the health and functioning of freshwater lakes. However, it’s very expensive and time-consuming for scientists to sample and map aquatic plants manually, particularly given that there are thousands of lakes in remote areas of Sweden. Birk and Ecke’s article outlines how developments in drone technology allow the mapping of aquatic plants at a 5cm scale, which means that plants can potentially be identified to species level at a quarter of the cost of manual surveys. This high image resolution – higher than previously possible using satellite remote sensing – potentially allows for more detailed remote monitoring of lakes.
Sebastian Birk describes the forward-thinking focus of this study:
“Drones give an opportunity to economically monitor the effects of anthropogenic stress to the myriad of lakes in the boreal zone. Field sampling is a costly exercise involving at least two surveyors snorkeling or sitting in a boat. And even then, you have to reduce your efforts to selected transects, not covering the entire lake. Using the drone is much easier, provided that the pictures taken by the drone are processed automatically, which is not yet possible.”
A large proportion of global lakes – especially those in boreal and tropical environments – are ‘coloured’ due to dissolved solutes in the water (especially organic carbon). Aquatic plants in coloured lakes mostly have floating or emergent (i.e. partially above the surface) leaves, which allow their photosynthetic tissues (those that create energy for the plant from sunlight) are exposed to the sun above the murky water.
Birk and Ecke studied 72 cloudy Swedish lakes to assess the potential of using emergent and floating plant species which can be detected by drones as proxies for predicting the ecological status of the lake in which they live. This process found strong correlations between the potential of drone-detectable species and those which are undetected, suggesting that remote sensing by drones could provide accurate assessments of the overall vegetation and health of coloured lakes.
Sebastian Birk outlines the potentially wide-ranging impacts of drones on freshwater monitoring:
“In an era of global austerity economic solutions tackling environmental issues are in demand. Our study demonstrates that drones offer useful services in ecosystem monitoring and assessment. Water management, in particular, requires extensive data that drones acquire most cost-effective. This could bring this technique from specialist application (e.g. real-time ecological research missions) into regular field survey: instead of boat and rubberboots, the surveyor now packs airplane and remote control.”
The next stage, of course, will be to put these ideas into practice by flying experimental drones over freshwater ecosystems. How long before every University research department has its own fleet of ‘eco-drones’? What legal and ethical issues will scientific researchers encounter with drone monitoring? Will the technology usher in a new era of ‘fortress’ conservation where drones are used to remotely monitor wildlife – and potentially people – in national parks and other protected areas? Or are drones simply more accurate, more affordable versions of existing satellite remote sensing technology, which is widely – and largely uncontroversially – used already?
Continuing our series of video interviews with project members, this week we feature Damià Barceló, Director of the Catalan Institute for Water Research in Girona, Spain. Damià leads the Globaqua project which – like MARS – studies the impacts – and interrelationships – of multiple stressors on our rivers and lakes. Unlike MARS, Globaqua is particularly concerned with understanding the effects of water scarcity and chemical contaminants such as pesticides on freshwater ecosystems.
Water scarcity is particularly important in Europe, partly because historically it has not been recognised by the Water Framework Directive, and partly because many rivers are temporary and do not flow year round from source tosea, especially in southern regions of the continent (see our blog on the topic). It is still only partially understand how freshwater ecosystems respond when exposed to water scarcity.
Similarly, chemical contaminants can have adverse effects on freshwater ecosystems. For example, in previous studies, Barceló’s research has documented how high levels of beta blocker pharmaceutical drugs in freshwaters caused daphnia to grow quickly to sizes much larger than on other parts of the river.
Globaqua will study the impact of global change on six river basins in Europe and North Africa: Ebro (Spain), Evrotas (Greece), Sava (a tributary of the Danube that flows through eastern Europe), Adige (in the northeast of Italy), Anglian (in the UK), and the Souss Massa (in Morocco). The different environmental and socioeconomic characteristics of each basin will be assessed, and different climate change scenarios will be modelled to forecast ecosystem service provision and the impact and interaction of multiple stressors for each basin in the future (e.g. under flood vs under drought).
In conjunction with MARS, Globaqua will help model scenarios of stress on freshwaters to help understand how ecosystems might react to different stressor levels and interactions. This work will go towards revising and strengthening EU water policies, particularly River Basin Management plans as part of the Water Framework Directive. In this interview, Damià emphasises the diversity of river ecosystems across Europe, and argues that a revision of the Water Framework Directive (due by 2019), should embrace this complexity to produce different management plans for each river.
We’ll continue to follow the Globaqua project as it develops, and report back on its findings.
The effects of climate change are already beginning to be seen on European lakes, according to new research. As profiled in a recent National Geographic feature, which references the MARS and REFRESH projects, Erik Jeppesen of Aarhus University, Denmark suggests that a warming and increasingly volatile climate is causing increasing algal blooms in European lakes, and fundamentally altering aquatic food webs, including the size and distribution of fish populations.
Jeppesen suggests that the ecological resilience of lake ecosystems can be increased through reducing the amount of nutrient pollution that is released into them, “The benefits are clear because of the synergistic effects between temperature and nutrient loading. Reducing the amount of nutrients available also increases the resilience of a lake to climate change.”
“Anglers are the eyes and ears of the waterside. They spot pollution and other problems before anyone else, and their knowledge of the water environment means that they can tell when something is wrong.”. Mark Lloyd, chief executive of the Angling Trust is putting the case to me in favour of anglers as good conservationists of Britain’s freshwaters.
“Freshwater anglers have to buy a rod licence to fish legally, and the licence fees provide £23 million to the Environment Agency to look after rivers and lakes. Angling is often the reason why new ponds and community facilities are built, often in conjunction with local authorities and environmental NGOs. Often this role has helped ‘reclaim’ former industrial landscapes, and contributed to urban regeneration. The Trust’s non-profit legal arm – Fish Legal – takes legal action through the civil courts against polluters and others who damage the water environment on behalf of its member angling clubs and riparian owners who are directly affected.”
Do anglers make good conservationists, and does angling benefit conservation? We’ve written on this subject before here, and many of the arguments in favour are strong. Freshwater angling is a phenomenally popular pastime – in the U.K. alone over 1 million licences are sold by the Environment Agency each year. This large, varied supporter base has the potential to create a large, vocal movement championing freshwater conservation issues, many of which are initiated through the Angling Trust. As Lloyd explains: “In the 5 years since The Angling Trust has formed we have mounted major campaigns on diffuse agricultural pollution, sewage discharges, water abstraction, fracking, barriers to fish migration, invasive non-native species, challenging flawed initiatives to dredge rivers to stop them flooding and a host of other issues.”
More widely, a 2012 report “Fishing for Answers” described a range of social and community benefits of angling observed over a three-year study carried out by British academics, describing the way that angling can encourage a deeper understanding and potential stewardship of the environment. Another high-profile example is that of Icelandic businessman and angler Orri Vigfusson, who won a Goldman Environmental Prize in 2007 for his work in buying out commercial salmon nets through his North Atlantic Salmon Fund coalition, as a means of reducing barriers to salmon migration.
On a European scale, the European Angler’s Alliance brings together organisations like the Angling Trust with a mission to: “safeguard the fish stocks and fisheries of Europe and to protect the interests of all those who fish with rod and line for recreational purposes”. A stated aim of the EAA is to promote sustainable recreational fishing which actively helps conserve or restore the health of the freshwater environment. The size and structure of the EAA means that it has the leverage to effectively lobby European policy decisions on key freshwater conservation issues like the Water Framework Directive.
Although there is much to be said for angler-led conservation, there are times when the conservation priorities of anglers don’t align with those of other environmental groups. Here, we might ask: does the conservation approach championed by anglers support only the species and habitats that they value for their sport? What about species that potentially challenge this, like the otter? The widespread reintroduction of otters to British freshwaters has not been met with universal support, with some anglers calling for culls to protect fish stocks in their (often artificially stocked) waters. It’s interesting to note how in examples like this Daily Telegraph article from 2009 fish stocks are not valued for their intrinsic worth as animals, but instead as financial investments, with the editor of Angling Times bemoaning that “£20,000 of [fish] stock can disappear in a few days” due to otter predation.
For the Predation Action Group, patronised by a number of well-known anglers, the line is even stronger, with otters described as “a giant predatory, aquatic rats with Doberman-like teeth” which can “decimate well stocked carp waters where the investment could well top several hundred thousand ponds“. It’s clear here that despite the fact that in many cases conservation and angling interests align, some issues – such as otter reintroductions – are potentially complicated by financial, commercial and sporting priorities.
I ask Lloyd how the Angling Trust might define their broad approach to conservation, a question which – after a long pause – was met with pragmatism, “Idealistically it would be about restoring functionality and allowing natural processes to work, perhaps even bringing back top predators like bears and lynx. But pragmatically, we live on an overcrowded island, with a managed environment where we need to make interventions.”
Do the conservation priorities of anglers always tally with the priorities of other environmental groups? “On the vast majority of issues, the interests of anglers are precisely aligned with conservation groups. There are a very few cases where they are not. For example, the Angling Trust believes that – in the context of drastically degraded fish stocks – there is a good case to be made for more lethal control of cormorant numbers (many of which are from a non-native sub-species that was previously only found in Eastern Europe). On this point we have held a different position to the RSPB, but have continued to work very closely with them on a wide range of other initiatives to protect, restore and improve the water environment.”
The discussion turns to a topic that has made headlines recently: what to do with the beaver populations found at the start of the year on the River Otter in Devon? In a statement made in July, Lloyd and the Angling Trust strongly supported the UK Government’s decision to remove the beaver populations, stating that the animals are non-native to Britain and can carry disease, a decision which has met with criticism from both the public and the press, perhaps most notably from George Monbiot in The Guardian.
Lloyd unequivocally outlines the Angling Trust’s position, “Although beavers were native to some parts of the British Isles more than 500 years ago, our rivers have changed dramatically in the past five centuries and suffer from endemic pollution, over-abstraction of water and the presence of tens of thousands of man-made barriers to fish migration. Nearly all fish species need to migrate up and down rivers in order to complete their life cycle and the addition of beaver dams would only increase the number of obstacles that fish have to overcome.”
Lloyd continues, “In a healthy natural ecosystem, beavers can actually be beneficial because they introduce woody debris to rivers and their dams can trap silt and create new habitats. However, less than 25% of England and Wales’ rivers are in good ecological condition and the Angling Trust’s view is that it would be irresponsible even to consider re-introducing this species into the wild without first restoring our rivers to good health by tackling low flows, pollution and removing the vast majority of man-made barriers to fish migration.”
Is there an argument that beavers don’t necessarily have to be the final piece in the river restoration ‘jigsaw’, instead central ‘ecosystem engineers‘ that might help create diverse, healthy ecosystems themselves? Lloyd’s response is less firm than before, “I take and understand that point. The Angling Trust has come out with a strong position on the release of captive beavers in Devon because their presence is unintended, and hasn’t been decided by public and political debate. If there was a widespread democratic vote in favour of their return then so be it, if we had the ability to break down dams and control numbers without much paperwork. What we can’t have is enthusiasts releasing caged animals.”
I ask a broader question: how do we decide the form and function that our freshwaters should take? Is there a historical baseline we can look back to for ecological inspiration? Again, a pragmatic and policy-aligned answer, “For Natural England the baseline for conservation seems to be a hypothetical post-glacial environment, but realistically you can’t turn back the clock. The agricultural and industrial revolutions have had such widespread impacts on our environments. Instead, we would look to the Water Framework Directive’s aim for ‘good ecological status’, which obviously isn’t going to happen everywhere by 2015. It’s about making compromises moving forward.”
I’m interested in this broader definition of what we might term ‘native’ and ‘non-native’ species in our freshwater environments. If we’re talking about removing beavers from UK freshwaters because they were hunted to extinction 500 years ago – and are thus defined as ‘non-native’ and unwelcome – does this same argument apply to fish like the sturgeon and burbot which once lived in UK freshwaters? Would The Angling Trust welcome their reintroductions?
“If habitats can be restored then we would support the carefully planned reintroduction of fish species such as sturgeon, burbot and indeed blue fin tuna which are now absent from UK waters. However, we believe that reintroducing species without first restoring the environment is the wrong way round; we should rebuild ecosystems from the bottom up, not the top down. We believe that there are very urgent priorities for the UK water environment that make such projects nice ideas for the future, but only once we have got the fundamental issues addressed: principally water quality, quantity, removal of barriers to migration, restoration of physical habitat (marine and freshwater). There are numerous strands to each of these elements and it will require substantial investment.”
Returning to the theme of anglers’ conservation priorities, I ask whether there is a contradiction in that some of the species widely targeted by British anglers occupy a grey area in terms of their ‘nativity’ to the UK. Take the wels catfish, for example, a species native to eastern, southern and central Europe, which was introduced to Britain around the turn of the 20th century, and can grow to huge sizes. Would the Angling Trust support anglers fishing for them?
Lloyd’s answer skirts any concrete definition of nativity, instead focusing on the Angling Trust’s role in representing their members’ interests, “We don’t support the presence of wels catfish in British waters. On balance, I think there’s more anglers who don’t want to fish for catfish than do, and those who don’t would prefer not to see them in British waters. We’re representing the view of the majority. Sometimes we need to show strong leadership on issues such as this, for example in recommending the stocking of only infertile trout, in order to protect the genetic integrity of wild populations.”
Talking about what might be native and what is not, we return to the topic of beavers. Lloyd thinks that the beaver’s attractive appearance is likely to complicate any management, “My concern with beavers is that their fluffiness and big eyes. If they were to be reintroduced, their presence would require management, for example to break down dams where their presence was undesirable. The Great British public is too sentimental about some wildlife, and management could prove difficult as a result if for example their presence proves undesirable, if dams mean that thousands of migratory fish can’t return to sea. There’s an irrationality to public opinion on fluffy animals like the beaver. How will riverside residents feel when the only tree in their garden is gnawed down overnight? Or a beaver dam floods a housing estate that has never before flooded? The problem with beavers is that they are very secretive and mainly nocturnal, and they don’t stay put, so they will spread from rural areas to villages and the edges of towns and cities.”
Lloyd is a persuasive interviewee whose answers show a clear desire to restore Britain’s freshwaters to a healthy state, yet also that any conservation or restoration management he advocates is likely to be shaped by the views of his constituents: Britain’s anglers. Broadly, anglers probably do make good conservationists – being immersed (hopefully not literally) in your environment can only help foster a positive environmental ethic. The work of organisations like the Angling Trust, European Angler’s Alliance and the North Atlantic Salmon Fund in giving support to conservation initiatives is also to be acknowledged.
But, as ever with conservation, there are no simple solutions to complicated issues. The support anglers give to conservation is always likely to be influenced by their own priorities, whether sporting (worries over whether beavers will block fish migrations of salmon and sea trout; introductions of non-native fish) or financial (the way in which the effect of otter predation is so often expressed in monetary terms for commercial, stocked fisheries).
Effective conservation is perhaps about trying to mediate these differences in opinion and aspiration for what form our natural environments should take, and how we can best manage them. Whilst we may aspire for our freshwater environments to become healthier and more diverse, what is not often noted is that the return of previously endangered species such as the otter (and potentially the beaver) in recovering freshwater ecosystems has the potential to create a host of new conservation issues to be solved.
Sustainable water management is one of the most pressing global environmental challenges, as growing human populations abstract, pollute and divert water flows across the world, whilst patterns of precipitation shift in response to a changing climate. The result is a situation where some parts of the world are facing more severe floods, whilst others are experiencing acute water scarcity. Global freshwaters are increasingly polluted, particularly in urban areas.
DESSIN is a new European Union project which aims to specifically address water scarcity and water quality issues in urban areas, partnering scientists with water management organisations and technology companies to attempt to design new and innovative solutions for water management. This work is particularly designed to help contribute to the European Water Framework Directive, which is undergoing a review in 2015.
DESSIN – Demonstrate Ecosystem Services Enabling Innovation in the Water Sector – focuses on new technologies and the ecosystem services concept as catalysts for providing new water management solutions, stating that the project “will be able to demonstrate how innovative solutions in the water cycle can increase the value of the services provided by freshwater ecosystems”.
The project has two broad aims: first to explore new technology and management approaches to address some of the world’s most pressing water issues; and second to use the ecosystem services concept to provide evidence of the benefit of new approaches in economic, social and environmental terms, in order to encourage their widespread adoption.
Five urban study areas have been chosen across Europe. David Schwesig, project co-ordinator at the IWW water centre in Germany explains how the sites were chosen: “When we were building the consortium for DESSIN, we were making a careful choice of demonstration sites which are representative of global major water challenges in the areas of water scarcity and water quality. Although solutions demonstrated in DESSIN need to be tailored to the specific local needs to some extent, we are aiming to deliver validated solutions with a high transferability potential to other sites with similar challenges, within Europe or even beyond”.
Different aspects of the DESSIN project will be investigated across these five sites. At Emscher in Northern Germany, the project will explore new approaches for sewage treatment in a landscape where river channels are being re-naturalised following a century of modification by industry. New technological solutions for monitoring and managing sewer overflows will be implemented at Hosselva, close to Oslo in Norway, as current water quality in local rivers is low, particularly during periods of heavy rain when the sewers flood. At Westland in the Netherlands, new techniques for extracting freshwater from brackish coastal aquifers (containing a mix of fresh and salt water) will be tested, using the reverse osmosis process to remove salt from the aquifer water.
Athens in Greece is one of the most water stressed cities in the world, and here the project will trial sewer mining as a means of sustainably reusing and recycling water to irrigate green spaces within the city. Finally, at Llobregat close to Barcelona in Spain a new deep groundwater injection system which can recharge underground aquifers will be trialled to help ensure freshwater availability during times of drought.
DESSIN aims to design and implement a new common evaluation framework for ecosystem services in partnership with the European ‘Ecosystem Services for Europe’ Action Group. As the first DESSIN newsletter (pdf) outlines, even when technological solutions to water problems are designed, there are likely to be barriers to their uptake by the market and policy makers: “Innovation uptake is limited by the difficulty of conducting comprehensive comparisons between the value of established technologies/management options and novel alternatives. In this context, the ecosystem services approach (ESA) may enable a standardised evaluation of impacts from innovations, in particular by integrating the economic, environmental and societal dimensions. Using the ESA to compare the potential of technologies and management options may help generate additional incentives and arguments for market uptake and practical implementation of innovations.”
We’ll continue to follow the DESSIN project as it develops and grows over the coming years, and report back on its findings.
The freshwater pearl mussel (Margaritifera margaritifera) is an extremely long-lived species of mollusc (a 134 year old mussel was found in Estonia in 1993), found in fast flowing rivers and streams across Europe. The pearl mussel produces small, beautiful pearls inside its thick shell which is anchored to the riverbed . However, freshwater pearl mussels are subject to increasing pressure, and their populations across Europe are listed as threatened by the IUCN due to habitat loss, declining water quality and illegal harvesting to provide pearls for jewellery.
Pearls in Peril is a European Union LIFE project set up to protect and conserve populations of freshwater pearl mussels in Great Britain. We spoke to project manager Jackie Webley from Scottish Natural Heritage to find out more about this fascinating species and the project’s important work.
Freshwater Blog: Freshwater pearl mussels are an absolutely fascinating species, although I’d guess that not many people know a lot about them. Can you tell me a little about their ecology? How are freshwater mussel populations faring in Britain at the moment?
Jackie Webley: Few people are fully aware of the significance of the freshwater pearl mussel, a species that lives ‘hidden’ in cold, fast-flowing rivers, yet is embedded in our history, culture and biodiversity. The freshwater pearl mussel is incredibly important as it filters river water, removing tiny particles for nourishment and by doing so helping to clean the water and benefiting other river wildlife.
The lifecycle of the freshwater pearl mussel is extraordinary. Adult mussels release up to 4 million microscopic larvae each summer. The larvae look like tiny mussels. They hold their shells open until they are inhaled by a young fish (Atlantic salmon or trout) then they snap shut on the fish gills. This association does not appear to harm the fish. The chances of a larva meeting a suitable fish are very low; only four in every million will do so. Nearly all are swept away by the river. The larvae remain on the gills of the fish and grow in this oxygen-rich environment until the following spring, when they drop off. They must land and burrow into clean, sandy or gravelly substrates in order to survive; if they land in silt or mud they will suffocate. The larvae that do survive can live for over hundred years, making them one of the longest-lived invertebrates.
The species has suffered a catastrophic decline globally and Scotland is now the stronghold of the remaining UK population. In Britain the freshwater pearl mussel is in urgent need of conservation action. Many of the rivers supporting this species contain old populations with no signs of reproduction, which is worrying as the freshwater pearl mussel is a barometer of the health of our river ecosystems.
Why are freshwater pearl mussel populations in decline?
Freshwater pearl mussels have been, and still are, affected by a range of factors causing their decline such as illegal pearl fishing, silt and soil washing into water courses, pollution and unauthorised river engineering. Mussels rely on young Atlantic salmon and trout to complete their lifecycle meaning declines in these fish will affect the survival of freshwater pearl mussels. Climate change is also considered to threaten the future of this species. A predicted increase in strong, fast flowing currents can dislodge pearl mussels from the river bed washing them downstream. Alternatively, an increase in drought conditions will result in low water levels, high water temperatures and reduced availability of oxygen. Under these parameters freshwater pearl mussels are too stressed to reproduce and mussel beds found along the river margins are likely to die from exposure.
Which rivers support the last populations?
In the last 100 years more than one-third of rivers in Scotland that used to contain mussels, no longer do so. England and Wales each have one viable population that is reproducing and collectively have an estimated population of 500,000 mussels. The UK estimated total population is 12 million, the majority of these surviving in Scotland and most of these occurring in just a few rivers.
Were populations once more widespread?
Freshwater pearl mussels used to be widespread and could be found in many rivers throughout the UK. There are a total of 23 sites in the UK that are designated for freshwater pearl mussels, other rivers where they are present are generally not mentioned due to a continuing risk from illegal pearl fishing.
Tell us about the Pearls in Peril project: how are you working to conserve mussel populations?
Pearls in Peril (PIP) is an ambitious £3.5million LIFE project that aims to safeguard the future of the freshwater pearl mussel by implementing a range of conservation measures across 21 designated sites. The project will run until September 2016 and includes rivers in England, Scotland and Wales.
The project is working to conserve mussels through practical measures such as ditch blocking, tree planting and fencing off river banks to restrict livestock access. These measures reduce silt and soil inputs, prevent bankside erosion, provide shade to reduce water temperatures and provide food and habitat for fish. PIP is working to restore river bed habitats where these have been destroyed from historic river engineering, is conducting artificial encystment (introducing freshwater pearl mussel larvae onto fish gills) and undertaking a range of monitoring actions.
PIP employs a Riverwatcher who is working to increase awareness of wildlife crime affecting pearl mussels, educating local communities on ‘what to look out for’ and ‘how to report’ information. The Riverwatcher works closely with Police Scotland and the National Wildlife Crime Unit sharing intelligence and reporting incidents. Through the project partners, PIP is delivering ‘Pearls in the Classroom’ to primary schools close to the rivers in the PIP project.
It seems that outreach and engagement with local communities is an important part of the Pearls in Peril project, through your Riverwatch and Pearls in the Classroom initiatives. Could you tell us a little more about these initiatives? Is it easy to engage people with a rare creature that many people won’t have seen?
The majority of people we speak to are usually fascinated to hear about the freshwater pearl mussel and are often quite amazed that such an important species has been living in the river on their doorstep. For those who already know about the mussel, memories are often re-awakened and we hear stories about the antics of the old pearl fishers or the thousands of shells washed into fields after large floods and the best places to look for mussel beds. People often talk about the mussels as though there are old friends that have always been there.
We are very pleased to engage with local communities. Our project partners are delivering Pearls in the Classroom (PiC), visiting local primary schools and looking at the species’ unusual lifecycle and that of its host species (salmon and trout). We discuss why the pearl mussel, salmon and trout are such an important part of the local river ecosystem. The children are given worksheets, activities and where possible, they visit the river bank with River Trust biologists.
The PiC programme also looks at how mussels can be conserved. This message is being delivered to a wider audience through Riverwatch, which aims to raise awareness of the problems pearl mussels face from criminal activity. Riverwatch Schemes are currently being established and will be promoted in the local media and with relevant stakeholders including fishery boards, fishery trusts, local communities, the police, conservation groups and others. PIP has employed a seasonal Riverwatcher who has so located evidence of illegal pearl fishing, unauthorised river engineering, pollution and gained important intelligence that has been passed to the National Wildlife Crime Unit and Police Scotland.
Is illegal pearl fishing still an issue?
Illegal pearl fishing is still an issue, seriously threatening the survival of freshwater pearl mussels – there simply are not enough mussels to sustain this exploitation which is why it was made illegal in 1998 and the species given full protection. There are other serious threats to the survival of mussels that can be addressed through practical conservation measures. We have had a mixed response across the UK from land managers and are pleased to say that in the majority of sites we have achieved very positive results.
If all goes to plan with the Pearls in Peril project, how will UK populations of freshwater mussels be faring in 2016? How about in another 50 years?
It will take many years to measure the effects of the conservation work happening now on freshwater pearl mussels given their reproduction rate (maturing between 10 – 15yrs old) and long life span 100yrs. Conservation work is aimed at improving habitat based on information provided by a range of research on the habitat requirements of this species. Water quality and fish populations are being monitored to allow us to see more immediate changes in conditions.
In another 50 years… we have to look positively at this species future, they are integral to a healthy river ecosystem and form a significant part of our culture and history. We would expect to see more populations successfully reproducing and a halt in the decline of the freshwater pearl mussel. Long may the stories continue…