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The DESSIN software tool for ecosystem service assessment in urban freshwaters

December 14, 2018

dessin headerA guest post from the DESSIN project

A new software tool for Ecosystem Service (ESS) assessments is now available. The DESSIN ESS software tool helps environmental practitioners and decision-makers identify, measure, and value ESS, particularly in urban freshwater environments.

The DESSIN ESS software tool was developed by the EU FP7 DESSIN project and is now supported by DHI, one of the project partners. The main objective of DESSIN was to demonstrate innovative solutions for water management, along with a methodology for measuring and valuing ESS.

DESSIN ran from 2014 to 2017, and was based on the assumption that a better understanding of ESS values can help us assess the potential benefits of innovative technologies that reduce water scarcity and improve water quality. Measuring changes to ESS helps us translate impacts on ecosystems to impacts on human welfare, broadening the scope of cost-benefit analysis, and stimulating the update of innovative technologies to help strengthen water management.

The DESSIN methodology for measuring ESS was described in the DESSIN ESS assessment framework and has been formalised into a reproducible methodology through the DESSIN software tool. The software tool is now available for free as part of DHI’s MIKE Workbench software and can be downloaded here.

Dr. Sebastian Birk, director of the MARS project, says, “The DESSIN ESS assessment framework is a state-of-the-art approach for assessment of ecosystem services in urban freshwater settings. The DESSIN software tool makes it easy to apply the framework in a way that is consistent and reproducible.”

The DESSIN ESS software tool facilitates the rapid and comprehensive assessment of ESS services and corresponding economic values in a study area. The tool is geared towards the assessment of available technical and management measures, the potential effectiveness of which can be compared to a ‘no-action’ baseline.

DESSIN DPSIR

The DPSIR framework for ecological management.

Ecosystem services are services provided by nature to humans, and the DESSIN ESS assessment framework assumes that the level of ecosystem service provision is a function of the state of the ecosystem. Therefore, improvements to the state of the ecosystem are related to better provision of services. The framework begins with a comprehensive assessment of the underlying ecosystem state, which is then related to the provision of ESS. The framework is based on the DPSIR framework (Drivers, Pressures, States, Impacts, Responses), which is widely used in environmental assessments in Europe.

The DESSIN ESS assessment framework links ecosystem state to ESS provision, use, and value through a complex chain of relationships that are captured in a database. The DESSIN software tool provides access to this database in a user-friendly way that makes it easy to apply the framework and keep track of these relationships. It consists of a comprehensive indicator database, including ecosystem state, provision, and use indicators, as well as database of economic valuation methods and studies.

DESSIN locations

Map of DESSIN case studies.

During the DESSIN project, the software tool was applied at five demonstration locations in Europe, to estimate the impact of innovative technologies on ecosystem services, along with associated impacts on human welfare:

In addition, the DESSIN software tool was tested during development on a case study in Aarhus, Denmark, where it was used to evaluate an urban river restoration project.

Niels Riegels from the development team at DHI says, “The DESSIN software tool provides a straightforward way to apply the DESSIN ESS assessment framework. The tool organises information in an accessible database and facilitates easy linkages to any data and models used to support the assessment.”

For more information about the DESSIN software tool, please contact Niels Riegels at ndr@dhigroup.com.

More information:


Download the DESSIN software tool


Read about the DESSIN ESS assessment framework


Visit the DESSIN project website

The AQUACROSS Assessment Framework: supporting effective floodplain restoration in the Danube Basin

November 30, 2018
CS3_Danube2_Andrea_Funk

A fallen tree on the bank of the Danube River. Image: Andrea Funk | AQUACROSS

The Danube is one of the great rivers of Europe, with a catchment of 800,000km2 which is home to more than 80 million people from 19 countries. The diversity of human life in the Danube basin is mirrored by its biogeographic diversity, moving from high Alpine mountain streams to looping lowland meanders and floodplains as the river flows 2,800km eastwards to its estuary in the Black Sea. As a result, the Danube basin provides habitat for a rich range of biodiversity, notably for wetland birds, freshwater molluscs and fish, including five species of endangered sturgeon and the Danube salmon, or huchen.

Sadly, the numerous human activities in the Danube basin have placed significant pressures on the ecological health and status of the river. Throughout the basin, the construction of hydropower plants, expansion of agriculture, and large-scale river regulation measures for navigation and flood protection are causing extensive hydromorphological pressures on the river ecosystem. As a result, in many parts of the Danube basin, natural floodplain areas have been disconnected from the river channel, or lost altogether, causing significant ongoing losses of habitat and biodiversity.

Multiple pressures, multiple policies

In response to these pressures, schemes to restore river-floodplain systems have been developed throughout the Danube basin. These restoration schemes relate to the implementation of a number of wider policy instruments, including the EU Biodiversity Strategy to 2020, the EU Strategy of the Danube Region, the Danube River Basin Management Plan for the Water Framework Directive, the EU Floods Directive, and the Birds Directive and Habitats Directive.

The diversity of these policies reflects the range of potential benefits to biodiversity, ecological status, natural flood protection and climate change mitigation that river-floodplain restoration can foster. However, the complexity of environmental problems and cross-border legislation in the Danube basin, coupled with a lack of adequate ecological data on the river ecosystem has significantly hampered floodplain restoration efforts. As a result, only a few countries in the Danube region have already implemented (or even planned) restoration activities, which are due by 2021.

Danube River Basin District Map

The Danube is the ‘most multinational river in the world’ according to the WWF. Image: ICPDR

The AQUACROSS Assessment Framework

To try to support floodplain restoration efforts across the Danube basin, the EU AQUACROSS project undertook research on the river using their Assessment Framework. The framework addresses three main factors to identify suitable sites for restoration and conservation. First, the remaining ‘multi-functionality’ of the system, in other words, the health and diversity of the ecosystem, even when highly pressured by human activities. Second, the ‘reversibility’ of the degraded ecosystem, or the potential to restore a multi-functional ecosystem. Third, the availability of remaining semi-natural land versus agricultural land in riparian areas around the river channel.

Essentially, the AQUACROSS Assessment Framework allows for the identification of sites for floodplain restoration where habitat, biodiversity and ecosystem service provision can be improved concurrently. The Framework is based on the joint application of Bayesian Biodiversity models and Ecosystem Service Models (ARIES). This integrated approach, which brings together multiple objectives for promoting biodiversity, ecosystem services and socio-economic benefits together, is designed to facilitate the implementation of ecosystem-based management in the Danube basin.

Assessing ‘baseline’ and ecosystem-based management approaches

When the AQUACROSS Assessment Framework was applied in the Danube basin, indicators for biodiversity, ecosystem services (such as flood retention, crop pollination and recreation potential), pressures (such as hydromorphological alteration) and drivers (such as land-use and hydropower) were modelled for two future scenarios: baseline (i.e. ‘business as usual’) and ecosystem-based management. At all stages, this process was supported by engagement with stakeholders across the basin.

The AQUACROSS results suggest that a ecosystem-based management approach can be more cost-effective in restoring floodplain biodiversity and ecosystem services than the baseline approach. They indicate that the multiple priorities considered by the ecosystem-based management create the opportunity to pursue different policy objectives simultaneously, and in so doing offer the potential to foster cross-border coordination of policy implementation and data sharing for floodplain restoration.

The AQUACROSS team highlight that the ecosystem-based management approach can thus help support the selection of restoration sites, whether under Habitats Directive protected areas, Water Framework River Basin Management Plans, or Floods Directive Flood Management Plans. In short, the AQUACROSS Assessment Framework provides an invaluable tool for helping restoring the health and status of the Danube basin under multiple human pressures.

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A connected floodplain sidearm channel of the Danube. Image: Andrea Funk | AQUACROSS

Reflections on the AQUACROSS Danube project

Andrea Funk, a lead AQUACROSS scientist on the Danube case study says, “Linking available multi-disciplinary data within a new model framework allows us to systematically prioritise floodplain segments along the Danube for conservation and restoration, partially confirming already designated restoration sites, as well as identifying others in areas where no sites are yet designated.”

Thomas Hein, a lead AQUACROSS scientist on the Danube case study says, “The cooperation of different leading scientific institutions and key stakeholders in the Danube River Basin allowed to define highly relevant research objectives and provided new results on a quantitative modelling approach to identify the biodiversity and ecosystem service potential and thus, the potential for floodplain restoration.”

Ursula Scheiblechner, Project Manager with Danube river management stakeholder organisation viadonau says, “The AQUACROSS Danube case study gives us a very large-scale view from source to the mouth of the river Danube. viadonau has a decades-long tradition of realizing ecological projects at the Danube in Austria. During the planning and construction phase of a project we have to look very close at the particular project area and several effects of the measures. It was interesting for us, that the AQUACROSS Danube case study with its large- scale analysis comes to similar conclusions in determining relevant restoration sites at the Danube as we do.”

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Find out more:

AQUACROSS Project

AQUACROSS Danube River Basin Case Study Executive Summary

AQUACROSS Danube River Basin Case Study Full Report

Managing multiple stressors in aquatic ecosystems: recommendations from the MARS Project

November 22, 2018

mars recsManaging and restoring aquatic ecosystems affected by multiple stressors is a key contemporary challenge for environmental scientists, managers and policy makers. As we’ve documented on this blog over the last few years, many European water bodies are subject to multiple human pressures such as pollution, climate change, hydrological and morphological alterations.

Such pressures can cause stress to the health and status of aquatic ecosystems. A stressor can represent either the immediate cause of decreasing ecological status (e.g. oxygen depletion caused by high water temperatures), or be part of a chain of factors which cause ecological degradation. In other words, stressors are how human pressures directly affect ecosystems.

The stressor concept allows us to outline both how human pressures can stress ecosystems in numerous ways, and to be specific about why a water body might not reach good ecological status as a result of the presence of different stressors.

mars pressure stressor

Stressors are how human pressures directly affect ecosystems. Image: MARS

Between 2014 and 2018, the EU FP7 MARS project investigated the interactions and impacts of multiple aquatic stressors, resulting in more than 200 scientific publications and an extensive range of online tools for water management.

This week, the project has published a document titled “MARS Recommendations on how to best assess and mitigate impacts of multiple stressors in aquatic ecosystems”. This open-access pdf outlines a framework for how multiple stress conditions might be best mitigated in River Basin Management through the EU Water Framework Directive.

The MARS framework supports environmental decision-making by providing tools and guidance for water managers to identify dominating and interacting stressors. Whilst multi-stressor situations vary between ecosystems, three broad guidelines for their management are identified.

First, where there are dominant individual stressors (e.g. water pollution), these should be the main priority for mitigation. Second, where stressor interactions are antagonistic (i.e. they ‘cancel each other out’ to some extent – e.g. nutrient and water flow increases), then the non-antagonistic stressors present should be targeted for mitigation. Finally, where stressor interactions are synergistic (i.e. they have effects ‘more than the sum of their parts’ – e.g. nutrient and temperature increases), then all present stressors should be targeted simultaneously, as far as possible.

MARS Qs for stressor management

Key questions for tackling multi-stressor conditions in River Basin Management using MARS outputs. Image: MARS

MARS research has demonstrated that there are some general patterns between stressor pairs, particularly in waterbody type specific interactions between nutrient and temperature fluctuations in lakes. However, the new recommendations document emphasises that assessment of stressor interactions and impacts, and planning measures for their mitigation, requires case-specific assessment. In other words, whilst there are some broad guidelines for managers to follow, the stressor conditions in individual waterbodies are key in guiding specific management approaches.

MARS provides a number of open-access online tools to help water managers diagnose and mitigate aquatic stressor conditions. These allow users to explore large spatial datasets on European stressor distributions and effects, and to examine cause-effect relationships between pressures, stressors, ecological status and management measures.

Other tools allow users to select the most suitable computer models to support their River Basin Management, to diagnose the causes of ecological deterioration based on biological metrics, and to visualise current and future multiple-stress conditions and ecological status in European rivers and lakes. Heat maps provide an innovative visual means of identifying how two stressors interact, and how mitigation efforts might shift an ecosystem towards good ecological status.

mars heat maps

MARS ‘Heat Maps’ of stressor pairs showing the expected gradient between ‘good’ and ‘moderate’ ecological status achieved by reducing stressor levels in additive (left) and synergistic (right) conditions. Image: MARS

The document also provides examples from seven MARS case studies to show how theory has been applied in practice, and to highlight key questions for River Basin Management.

Broadly, the recommendations from the MARS project show how the large datasets about European aquatic ecosystems (much of which is generated through Water Framework Directive monitoring) can be used to improve River Basin Management Planning. More specifically, it shows how the emerging environmental issue of multiple stressors – arguably a key signal of the Anthropocene in freshwaters – can be addressed by agile and responsive science and management.

MARS has significantly raised the profile of multiple stressor issues in scientific, policy and public realms, and provided an extensive range of information, tools and resources for users to implement in environmental management and restoration. Now is the time for this information to be applied and extended. With the publication of the new MARS recommendations document, there are reasons to be optimistic over the prospects for the health and status of European aquatic ecosystems in the future.

Read MARS Recommendations on how to best assess and mitigate impacts of multiple stressors in aquatic ecosystems

MARS EU FP7 Project

Freshwater Information Platform

 

Global freshwater species populations decline by 83% since 1970

November 7, 2018
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The Zambezi River in Africa: home to diverse populations of wildlife, but increasingly pressured by water pollution and dam construction. Image: Ninara | Flickr Creative Commons

Global freshwater species populations have dropped by 83% since 1970, according to a new report published by the World Wildlife Fund. The Living Planet Report 2018 assessed the populations of 880 representative freshwater species across the world between 1970-2014 to calculate the Living Planet Index.

The WWF report states that freshwaters – including lakes, rivers and wetlands – are the most threatened of all global habitats. Freshwater ecosystems provide habitat for over 100,000 known species of fishes, molluscs, reptiles, insects, plants and mammals, despite covering less than 1% of the Earth’s surface.

Overall, freshwater habitats are home to more than 10% of known animals and about one-third of all known vertebrate species. However, as the new figures show, freshwaters are experiencing significant biodiversity loss. The report identifies multiple pressures driving biodiversity loss including habitat modification, fragmentation and destruction; invasive species; overfishing; pollution; disease; and climate change.

wwf freshwater lpi 2018

Image: WWF

The report highlights the importance of ‘connected and free-flowing’ rivers in supporting healthy freshwater ecosystems, and the human populations which rely on them. When reservoir or hydropower dams are built, rivers straightened and their banks reinforced, or floodplains built on, the natural processes that take place throughout a river system are often damaged. Such processes often include fish migration, the dynamics, temperature and volume of water flows, seasonal flooding (and floodplain fertilisation) and sediment movement.

A recent scientific paper estimates that around half of global rivers are significantly impacted by flow regulation and/or fragmentation. As the report highlights, this means more than a quarter of the sediment which was naturally transported by global rivers to the ocean each year is now being trapped behind dam walls in reservoirs. Assuming the completion of all dams planned and under construction, it is predicted that the global percentage of rivers which are fragmented or regulated would nearly double to 93%, largely due to major dam construction in the Amazon Basin.

Increasing demands on water have also significantly reduced the global number of permanent rivers and lakes in recent decades, the report highlights. Based on over three million satellite images analysed using the Water Explorer, it is estimated that more than 90,000km2 of previously permanent freshwaters have been lost or become intermittent. In other words, rivers and lakes which previously existed all year round are now either gone or dry for periods of each year, as a result of water abstraction, dam construction and flow diversions. Over 70% of this loss of surface waters is concentrated in just five countries in Central and Western Asia.

rio grande

Dry river channel on the Rio Grande, USA where water abstraction and dam construction have caused sections of the river to temporarily dry out. Image: JN Stuart | Flickr Creative Commons

In short, the regulation and disconnection of water flows through river catchments can throw complex and dynamic freshwater systems off kilter, and significantly alter the habitats they provide. This has contributed not only to the significant declines in freshwater biodiversity, but often also has negative effects on human communities who rely on freshwaters for food, water, and fertile agricultural land.

More widely, across all terrestrial, freshwater and oceanic ecosystems, the Living Planet Index calculates that global populations of mammals, birds, fish, reptiles, and amphibians have declined, on average, by 60% between 1970 and 2014, the most recent year with available data. This figure is based on data on 16,704 populations of 4,005 vertebrate species globally.

“This report sounds a warning shot across our bow,” says Carter Roberts, president and CEO of WWF-US. “Natural systems essential to our survival—forests, oceans, and rivers—remain in decline. Wildlife around the world continue to dwindle. It reminds us we need to change course. It’s time to balance our consumption with the needs of nature, and to protect the only planet that is our home.”

“In the next years, we need to urgently transition to a net carbon-neutral society and halt and reverse nature loss through green finance and shifting to clean energy and environmentally friendly food production,” says Marco Lambertini, Director General of WWF International. “In addition, we must preserve and restore enough land and ocean in a natural state to sustain all life.

But we have two main problems. First, and perhaps the greatest, is the cultural challenge. For too long we have taken nature for granted, and this needs to stop. The second is economic. We can no longer ignore the impact of current unsustainable production models and wasteful lifestyles. These must be accounted for and addressed.”

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The Mekong giant catfish, a critically endangered species native to the Mekong basin in South-East Asia. Image: Lynn Chan | Flickr Creative Commons

The report develops short-term and long-term imperatives for policy and management which can ‘bend the curve of biodiversity loss’ (a phrase from a related recent Nature Sustainability paper). First, it highlights a ‘window of opportunity’ between now and 2020 to strengthen environmental policy as new goals and targets are currently being set for the Convention on Biological Diversity (CBD).

Secondly, it develops a ‘roadmap for 2020 to 2050’ to halt biodiversity loss, calling for the ambitious goals of the CBD – “By 2050, biodiversity is valued, conserved, restored and wisely used, maintaining ecosystem services, sustaining a healthy planet and delivering benefits essential for all people” – to continue to provide the basis of global environmental policy and management. This goal can be supported by the ongoing development of more effective biodiversity indicators, and scenario models which predict biodiversity trends in the future, the report argues.

Overall, the message is one that ‘business as usual’ approaches to managing biodiversity loss are not enough, and that the debate needs to be reframed from one in which ‘nature is nice to have’ to one in which ‘nature is a need to have’. This is a process in which the political and social relevance of nature is radically escalated, in order to galvanise cohesive movements which drive positive environmental change. As the report concludes, “We are the first generation that has a clear picture of the value of nature and the enormous impact we have on it. We may also be the last that can act to reverse this trend.”

Read the WWF Living Planet Report 2018

Over a third of natural wetlands lost globally since 1970

October 25, 2018
dubai wetland

Ras Al Khor Wildlife Sanctuary in the UAE – a network of highly biodiverse salt flats, lagoons, intertidal mud flats and mangrove swamps below the Dubai skyscrapers. Image: Francesca Negrini | Ramsar

Over a third of natural wetlands have been lost globally since 1970, a rate of decline which is three times that of global forest loss over the same period. Wetlands are important habitats for wildlife, and provide a number of important ecosystem services to humans, including food security, flood protection and climate change mitigation. However, wetlands are being lost due to human development across the world, putting a quarter of the plants and animals which depend on them at risk of extinction.

These are some of the key findings of the new Global Wetland Outlook report, published by the Ramsar Convention on Wetlands, an international treaty on wetland conservation. The report – the first global wetland inventory of its kind – has been published to coincide with the 13th Ramsar Convention of Parties, held this week in the United Arab Emirates.

Covering around 12.1 million km2 globally – an area almost as large as Greenland – wetlands are often highly biodiverse ecosystems, and can variously include lakes, rivers, swamps, marshes, peatlands and mangrove. Wetlands play a major role in the water cycle by storing, regulating and releasing water flows, and can also provide natural flood protection. However, widespread land use change and water regulation has reduced connectivity between many river systems and floodplain wetlands, according to the new report. Many other global wetlands have been drained to provide land for agriculture and urban development.

kuwait wetland

Mubarak Al-Kabeer Reserve – a Ramsar site in Kuwait where shallow salt marshes and small lagoons provide a key habitat for migratory birds. Image: Abdualreda Alramzi | Ramsar

Wetlands also play important roles in nutrient and carbon cycles. They can help regulate aquatic nutrient levels as plant growth and sedimentation acts as a natural ‘filter system’ – a process which can also store pollutants such as trace metals. Similarly, wetlands are important ‘sinks’ for carbon. Despite occupying only 3% of the land surface, peatlands store twice as much carbon as the world’s forests, according to the report.

Despite their value to humans and non-humans alike – the report suggests that wetland ecosystem services far exceed those from terrestrial environments – wetlands continue to be damaged and destroyed across the world. Based on available data, the report estimates that between 1970 and 2015, the global area of inland and marine/coastal wetlands both declined by approximately 35%.

Human-made wetlands – largely rice paddy and reservoirs – almost doubled in area over this period, now forming 12% of wetlands, the report estimates. However, these increases have not compensated for natural wetland loss, nor do they generally provide the same habitat for biodiversity. Since 1970, 81% of inland wetland species populations and 36% of coastal and marine species have declined, and 25% of wetland species are at risk of extinction globally.

iraq wetland

Gathering reeds in the Hawizeh Marsh Ramsar Site in Iraq – the last significant area of the Mesopotamian marshlands complex largely drained in the 1990s. Image: Ramsar

The report argues that this ongoing loss of wetlands is caused by policy and decision-makers underestimating their value. They recommend expanding the network of Ramsar Sites (which currently number over 2,300) and other wetland protected areas globally, alongside strengthening legal and policy arrangements for wetland protection.

One key task is to improve national wetland inventories – through remote sensing, ecological field monitoring, citizen science and the consultation of local and indigenous people – to better understand the extent and value of global wetlands, and the threats they face. Such work can provide the basis to better governance and public participation in wetland conservation, the report suggests.

belarus wetland

Yelnia reserve in Belarus – a patchwork landscape of raised bogs and transition mires which provides important flood protection and nutrient filtration services. Image: Vershitskaya Irina | Ramsar

Martha Rojas Urrego, Secretary General of the Ramsar Convention says, “The loss of wetlands continues today, with direct and measurable negative impacts on nature and people. The purpose of the Global Wetland Outlook is to increase understanding of the value of wetlands and provide recommendations to ensure that wetlands are conserved, wisely used and their benefits recognized and valued by all.

The Ramsar Convention plays a unique role in championing this change. As the only international treaty focused on wetlands, it provides a platform of 170 Contracting Parties working together for wetland conservation and wise use, and to develop the best available data, advice and policy recommendations to realize the benefits of fully functional wetlands to nature and society.”

south korea wetland

A flock of oystercatchers on Seocheon Tidal Flat in South Korea. This open tidal flat is directly linked to the ocean, and provides habitat for migratory birds and spawning and nursery ground for fish. Image: Seochon-gun county | Ramsar

The report suggests that the UN Sustainable Development Goals provide an important policy framework through which wetland conservation might be better valued and addressed.

Rojas Urrego explains, “In the context of climate change, increasing water demands and increased risks of floods and droughts, wetlands are more critical than ever to achieve sustainable development. In fact, wetlands contribute directly or indirectly to 75 Sustainable Development Goal (SDG) indicators.

Of critical importance is the Convention’s leadership role in reporting on wetland extent as a co-custodian with the United Nations Environment Programme of SDG indicator 6.6.1. The Convention provides a platform like no other to foster collaboration and partnership to achieve other international policy objectives including the Aichi Biodiversity Targets, the Paris Agreement on Climate Change and the Sendai Framework on Disaster Risk Reduction to promote co-benefits and scale up the needed action to conserve and wisely use wetlands.”

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Read the The Global Wetland Outlook – Status and Trends 2018 report online.

Ramsar Convention on Wetlands 2018

Ramsar website

Microplastics found in fifty percent of insects in South Wales rivers

October 10, 2018
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The River Usk in South Wales. Half of the aquatic insects sampled in the river were found to contain microplastics. Image: Photo Monkey | Flickr Creative Commons

Microplastic pollution is a rapidly growing issue in aquatic ecosystems across the world. Microplastics are tiny pieces of plastic debris less than 5mm in size. They enter aquatic environments in two main ways. First, diffusely: through the erosion of larger plastic items such as drinks bottles, fishing nets and plastic bags. Second, directly: through the run-off of abraded road paints, textiles, and vehicle tyres, and in sewage containing plastic textile fibres from washing machines.

Plastics can take thousands of years to degrade and break down. As a result, understanding the impact of increasing microplastic pollution into aquatic ecosystems is an important emerging topic for environmental science and policy.

In marine environments, microplastics have been found in invertebrateszooplankton, shellfish, fish, and birds, and washed up on shorelines across the world. Whilst microplastics are present at all tropic levels in marine food webs, research is ongoing in understanding how this accumulation affects the feeding, growth, reproduction, and survival of aquatic communities. By comparison, our understanding of the extent and impacts of microplastic pollution in freshwater environments is relatively sparse (read our blog on the topic from 2015 here).

Microplastics widespread in South Wales rivers

A new open-access study by researchers from Cardiff University found that half of aquatic insects (or macroinvertebrates) sampled from three rivers in South Wales had ingested microplastics.

A research team led by Fred Windsor, a PhD researcher at Cardiff University School of Biosciences, sampled three different kinds of mayfly and caddis larvae at five sites on the Usk, Taff and Wye catchments. Each sampling site was located close to a waste water treatment plant, allowing macroinvertebrates to be sampled both above and below water outflows from each plant.

The researchers found microplastics at each of their five river sampling sites. These were found in individual insects across each of the three sampled macroinvertebrate species, regardless of their feeding methods, habitat preferences and ecological niche.

The research team found that, on average, microplastic levels were similar in river stretches both above and below waste water treatment plants. However, the researchers did observe that microplastic levels increased where waste water treatment plant outflows comprised a significant proportion of downstream river flows. This suggests that microplastic pollution originates from multiple sources – most likely transport networks and urban areas – across the wider landscape, rather than from discharge from waste water treatment plants alone.

Lead author of the study Fred Windsor says, “Every year, between eight and twelve million tonnes of plastics are thought to be entering the World’s oceans, but around four million tonnes of it passes along rivers. In some cases, there can be over half a million plastic fragments per square metre of river bed, so that ingestion by insects is very likely.”

microplastics

Microscopic images of the microplastics (A and B) and plastic fibres (C) found by the researchers in the three rivers. Image: Study Authors

The emerging environmental risks of microplastic pollution

Co-author Professor Steve Ormerod, Co-Director of Cardiff University’s Water Research Institute continues, “Urban rivers in the UK have been recovering from decades of gross pollution, but growing information illustrates that plastics are a new risk for river organisms not just in towns and cities, but even in some rural areas.

Problems could arise from the physical effects of microplastics, from their direct toxicity or from pollutants that they transport. Plastics in insects mean that animals using them as prey could also be affected. At present, however, our understanding of the risks to wildlife and people is absolutely rudimentary. We need to improve this situation urgently to know how best to manage the problems.”

The research team conclude that more research is urgently required to understand the sources and transport of microplastics in freshwater environments, and how microplastics are ingested and transferred across different organisms in freshwater food webs. Such research could allow scientists and water managers to develop more complete biological risk assessment approaches for mitigating the potential impacts of microplastics on freshwater life.

Microplastic pollution: a key topic for environmental science and policy

Professor Isabelle Durance, Director of the Water Research Institute at Cardiff University, adds, “Although people are more and more aware of the damage caused to ocean wildlife from ingesting plastics, the potential problem of plastics in river ecosystems has been seriously overlooked.

“The water industry, environmental regulators, the plastics and packaging industries, and ordinary people concerned about the environment see this as an increasing priority, and this study provides yet more evidence that we need a fuller assessment of the sources, movements and effects of microplastics as they are transported between the land and sea along rivers.”

The interconnection of freshwater and marine environments highlighted by Prof Durance – in which microplastics are transported through river catchments out to estuaries and the open sea – is a key aspect of this emerging environmental issue. For example, another recently published paper by Alexandra McGoran and colleagues found microplastics in a third of fish sampled in the Thames and Clyde estuaries in the UK.

As a result, the management of microplastic pollution in coming years is likely to require close co-operation between scientists, policy-makers and water managers across both freshwater and marine realms, both to understand the extent of the microplastic problem, and what can be done to mitigate its effects on aquatic life.

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Windsor, F. et al. (2018), Microplastic ingestion by riverine macroinvertebrates, Science of the Total Environment, Volume 646, 68-74 (open-access)

Lake type affects how climate change causes algal blooms in European lakes

September 28, 2018
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Algal bloom on Loch Leven in Scotland. Image: Laurence Carvalho

Blooms of blue-green algae – otherwise known as cyanobacteria – are likely to increase in European lakes as a result of climate change, according to a new study. However, this trend is likely to vary depending on the individual characteristics of different lakes.

Writing in Global Change Biology, Dr. Jessica Richardson from the Centre for Ecology and Hydrology and colleagues used data from lakes across Europe to explore the sensitivities of different types of lakes to multiple environmental stressors associated with climate change and human activities.

The research team – funded by the EU MARS project – wanted to find out how climate change effects, coupled with nutrient pollution, influences cyanobacteria growth. Characteristic ‘blue-green’ cyanobacteria blooms can be a common sight across Europe during the summer months, particularly in shallow lakes in agricultural or urban landscapes.

Whilst cyanobacteria communities are a natural – and valuable – part of almost all aquatic ecosystems, their rapid growth and spread – often following nutrient pollution during hot weather – can have adverse effects for the wider environment. Cyanobacteria blooms can cause hypoxic conditions with low dissolved oxygen levels, block light from entering the water column, and cause toxic health risks to humans and animals.

These effects can cause serious environmental and economic problems. As a result, understanding how and why cyanobacteria blooms occur in response to multiple stressors from human activities is important.

Gathering data from lakes across Europe

The research team used data on 494 natural European lakes to examine how eutrophication, temperature and prolonged periods of drought interact to influence cyanobacteria levels. The lake data was taken from the WISER database, and was based on scientific sampling of the individual lakes between 2000 and 2009.

The lakes were categorised into eight different types based on their alkalinity, the presence of humic substances (and consequently, the colour of the water), and the characteristics of water mixing in the water column. This categorisation was based on the common European lake typology scheme used in the Water Framework Directive. Lake data was paired with corresponding catchment and climate data from the same period, taken from the MARS geodatabase and JRC Agri4Cast Data Portal, respectively.

Clyndrospermum_(Cyanobacteria)

Clyndrospermum sp. – microphotograph of a species of cyanobacteria. Image: Matthew Parker | Wikipedia Creative Commons

Modelling the interactions and impacts of multiple stressors

Three key stressors were chosen for analysis in this study: total phosphorus, water temperature and water retention time. Phosphorus is a nutrient pollutant commonly found in aquatic environments – often originating from agricultural fertilisers, run-off from urban areas, or waste-water treatment plants – which at high concentrations can prompt rapid cyanobacteria blooms.

Water temperature increases are widely predicted in lakes globally as a result of ongoing climate change. Previous studies have examined the impacts of temperature increases on lake water quality and biodiversity, particularly in how warming might exacerbate the environmental impacts of nutrient pollution.

Water retention time is a measure of how long water is ‘resident’ in a lake. Retention time is higher during times of drought (when there are low water flows), and lower during periods of heavy rainfall (when there are high water flows). Cyanobacteria blooms can occur when water retention times are high, as a result of increased concentrations of nutrients (which are not ‘flushed out’ of the system) and stable physical conditions. Lakes in regions where lower rainfall and drought is predicted under future climatic changes are likely to exhibit increased water retention time.

The sensitivity of European lakes to climate change is influenced by lake type

Around a quarter of the lakes analysed in the new study had average cyanobacteria levels which exceeded the World Health Organisation ‘low risk’ threshold. The majority of these lakes were located in central Europe. Lakes with lowest cyanobacteria levels were found in the most northerly regions of Europe, following a pattern of decreasing temperature and phosphorus levels with increasing latitude.

Overall, cyanobacteria levels increased with temperature and water retention time in five of the eight lake types. The effects of temperature were greatest in lake types at high latitudes, which suggests that lakes in these regions will become increasingly at risk from climate warming in the future.

However, the sensitivity of cyanobacteria to phosphorus levels, water temperature and retention time varied with lake type. For example, cyanobacteria levels in shallow, humic lakes with medium-high alkalinity were explained by water retention time, and a synergistic relationship between phosphorus levels and temperature. However, in lakes with similar characteristics – but this time with clear (non-humic) water – only water retention time was identified as an explanatory variable for cyanobacteria levels.

In short, the sensitivity and response of European lakes to climate change is shown – in terms of impacts on cyanobacteria levels – to be strongly influenced by lake type. The researchers state that in most lake types, management will become increasingly necessary as the effects of climate change – higher temperatures and retention times –  impact lakes in the future. They suggest that as climate effects cannot be locally controlled, there is a need for effective management of nutrient pollution in order to minimise harmful algal blooms.

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Algal bloom on the Spree River in Berlin. Image: Lars Plougmann | Flickr Creative Commons

European lakes under climate change: a ‘perfect storm’ for cyanobacteria blooms?

Lead author Dr. Jessica Richardson from the Centre for Ecology & Hydrology says, “Lakes are getting warmer and also experiencing longer periods of water retention because of prolonged droughts. In human impacted, nutrient rich lakes we think that these conditions could be the ‘perfect storm’ for promoting blooms of cyanobacteria.”

In our study of almost 500 European lakes, we found that higher temperatures, longer retention times and higher nutrients do increase the amount of cyanobacteria but not to the same degree in all lakes. This is not very surprising as there are many different types of lakes which are sensitive to these stresses in different ways.”

This site-specific variation in the impact of multiple stressors on European lakes has important implications for environmental policy and management, as Richardson explains,

“While climate change and eutrophication are important risk factors in the development of cyanobacterial blooms, other factors which also affect the growth and competition of cyanobacteria with other algae, like the depth of the lake, the colour of the lake, or the location of the lake may be equally as important.”

This means that when it comes to risk management, and predicting future risks of cyanobacterial blooms, a ‘one-size fits all’ approach can’t be applied. Instead, we need to consider that management of different types of lakes may need to be tailored according to their sensitivities.”

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Richardson, J. et al (2018), Effects of multiple stressors on cyanobacteria abundance vary with lake type, Global Change Biology, https://doi.org/10.1111/gcb.14396

MARS Project website

 

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