Department Aquatic Ecology

A comparison of three Swiss lakes with the Great Lakes of North America show that the quagga mussel is spreading with a similar dynamic.

In the scientific journal Nature, a team including a member of Eawag published a study on the development of biodiversity in European inland waters, based on invertebrates.

Nutrient changes, invasive species and climate change have a major impact on the ecosystem of Lake Constance. This is the conclusion of a large-scale project conducted by seven institutions in Switzerland, Germany and Austria. At the close of the project, the results will be presented at two events.

The aquatic research institute Eawag has published its latest annual report and looks back on the year 2022. Water is at the heart of the most important environmental issues.

When glaciers retreat, the habitats for cold-water organisms also change. Researchers have now modelled where refuges that are vital for biodiversity in glacial rivers will remain in the future.

An Eawag study shows that a large variety of living organisms leave their DNA traces in groundwater – which also depends on the land use in the catchment area. In future, these biological parameters could be used to assess groundwater quality.

Ecologist Florian Altermatt has been promoted to full professor of aquatic ecology by the University of Zurich. What fascinates him about research and why is he committed to academic teaching?

A forest is crucial for life in streams, particularly in the catchment area and in the headwaters. This effect is especially significant in the case of sensitive species.

Thanks to a unique data set from lakes, Eawag has succeeded in determining how plankton networks respond to climate change and phosphate levels.

Martin Ackermann has been head of Eawag since January. At his request, the ETH Board has now appointed three new members to the Directorate. Lenny Winkel, Florian Altermatt and Christian Stamm, who now becomes deputy director.

Switzerland's groundwater is home to a multitude of hitherto unknown organisms. An Eawag research project is shining a light into the darkness and revealing this habitat’s exceptional biodiversity.

A new integrative approach to biodiversity research shows how ecosystems on land and in freshwaters can be better protected by considering fundamental ecological processes.

The Aqua Urbanica symposium, co-organised by Eawag, explored the question of what is needed to implement the sponge city concept. With the help of this concept, cities should be able to mitigate the consequences of climate change.

Terrestrial and aquatic food webs respond differently to changes in the environment. Understanding these differences is fundamental to identifying the species most important to an ecosystem and to effectively protecting biodiversity. This is shown by a study led by the research institutes Eawag and WSL and published in the journal Nature Communications.

Nature conservation pays off: amphibians benefit from new ponds - despite many causes of endangerment that still affect them. This is what researchers from WSL and Eawag found in a joint study using data from amphibian monitoring in the canton of Aargau. The study was published in the scientific journal PNAS.

A high fraction of the endemic biodiversity of the Alps is very old. The endemics – species found only in a confined area – have developed over the past millions of years during the cycles of glacial and interglacial periods or even before these cycles began. Fish, however, are an exception: most endemic fish species emerged only after the end of the last ice age about 15,000 years ago.

Insects that live entirely or partly in freshwater have a much lower proportion of invasive species than insects that live on land. This is shown in a study by the Swiss Federal Institute for Forest, Snow and Landscape Research WSL in collaboration with the Swiss Federal Institute of Aquatic Science and Technology Eawag and an international team of researchers.

Of over a thousand lakes studied worldwide, about one in ten shows strange behaviour. In general, there is an increasing tendency for aquatic ecosystems to tip over. The ecological stability of lakes is decreasing, especially in regions with low GDP and large human populations.

A facility with experimental ponds for field trials is located on the Eawag site in Dübendorf. The current experiment is investigating how the water lily aphid - a herbivore that lives both on land and on water - influences the development of the biocoenosis in water bodies.

Lake Greifensee is almost on Eawag’s “doorstep” and is therefore used extensively for its water research. Last Friday, interested visitors learned about how the researchers work and what they have discovered about the lake during an enjoyable boat trip. There will be another opportunity for this in autumn.

It is no secret that climate change has a serious impact on the quality and ecology of aquatic environments. Researchers at Eawag have revealed that human responses to climate change are just as impactful on our water systems – for example, in the areas of agriculture and hydropower.

In the future, drones could open up new possibilities for taking water samples fully automatically in remote areas. To this end, Eawag researchers tested a drone model developed at Empa and Imperial College.

Monitoring freshwater ecosystems by means of environmental DNA methods offers new opportunities for detecting invasive species. An Eawag study has shown that an invasive jellyfish is more widespread in Switzerland than previously thought.

A new study has shown how fish influence oceans’ ecosystems in coastal regions, revealing for the first time the role they play in distributing heat, nutrients and oxygen that keep the system functioning.

Artificial floods mimick natural flows to mobilise and transport sediment downstream, reshape the river and reinstate important habitats for native aquatic insects and fish. Improved outcomes can occur when these artificial floods converge with natural flows and sediment delivery from unregulated tributary streams further down the valley.

New research findings, and a resulting fact sheet, provide insights into the problematic spread of the invasive quagga mussel in Switzerland. The authors of the fact sheet are concerned that the aggressive spread of this mussel species will have a substantial detrimental effect on lake ecosystems.

Among aquatic insects in Swiss streams, those species that like it warm and can cope well with pesticide exposure are on the rise. This is shown by a joint study by WSL and Eawag using data from biodiversity monitoring between 2010 and 2019. The results indicate a possible influence of climate change.

The use of lake and river water to generate heat and cold is constantly increasing. The potential is enormous. Nevertheless, negative impacts on aquatic ecosystems must be avoided. A fact sheet from Eawag lists the key points in this regard.

Often overlooked until now: symbioses could be a driving force for the emergence of biodiversity. A case where bacteria live in aphids shows that this can even have practical implications for biological pest control.

The buffet of healthy insects starts earlier, is no longer as varied, and is only half as plentiful as it once was. This is the situation faced by insectivorous birds at Northern Temperate latitudes, such as Switzerland, during the breeding season. Ryan Shipley from the Eawag water research institute, has been investigating how climate change affects the timing and quality of the food supply for breeding birds.

In the "Projet Lac" research project, 35 lakes in the Alpine region were systematically examined for their fish populations for the first time: In Switzerland alone, 106 fish species were detected. With almost 20 percent of all known fish species in Europe, Switzerland is one of the hotspots for fish species diversity. The results are now the basis for measures for sustainable fishing and the protection of this still preserved diversity.

It makes sense to study land and water habitats together, according to the initial findings of the Blue-Green Biodiversity initiative.

With around 200 pictures and texts, the new Water Timeline takes you through 200 years of the eventful history of Swiss water protection. It aims to show how shifts towards more sustainable management of natural resources can be shaped. 

Eawag scientist Christopher Robinson is one of the main editors of this book on the biological and hydrological characteristics of more than 180 of the highest profile rivers in Europe.

Eawag intends to further develop artificial intelligence methods to enable their increasing use in water research. One current application is the monitoring of plankton communities in lakes. With the help of machine learning methods, it has been possible to implement an automatic classification of the microorganisms.   

Researchers Christoph Vorburger and Florian Altermatt talk about the importance and state of aquatic biodiversity in Switzerland and Eawag’s commitment to conserving natural biodiversity.

Rising temperatures, invasive species and other factors have changed the composition of species in Lake Constance over the last century. Researchers are trying to understand how this could have happened and what it means for the lake.

Our lakes, rivers and streams are teeming with the smallest creatures, plants and bacteria that are barely visible to the naked eye, if at all. An underwater camera makes it possible to observe and identify the species of these creatures in real time.

Whether a hydroelectric power plant is built, a pesticide is banned or a moor is placed under protection – a wide variety of political decisions have an impact on biodiversity. But does biodiversity play any role at all in such decisions? Researchers at Eawag and WSL have investigated this question and examined Swiss policy over the past 20 years.

Blue-green algae and other phytoplankton are very important for the proper functioning of aquatic ecosystems. When they accumulate in high quantities, however, they can be harmful to people and animals because some blue-green algae species produce toxic chemicals. For this reason, the aquatic research institute Eawag is currently working on methods to improve the prediction of bloom events.

Each year at Eawag, around 160 Master’s and Bachelor’s students are supervised and often directly involved in research projects. Again and again, this collaboration – as well as Eawag’s flat hierarchies and interdisciplinary culture – leads to outstanding Master’s theses.

Open Science is an important development in science - open access to the results of research. Eawag supports these and makes a growing part of its research data, including descriptions, images and even software, available publicly and free of charge on the Eawag platform ERIC or, in special cases, on discipline-specific, international databases. ERIC complements the long-standing platform DORA for scientific publications.

Groundwater is also an ecosystem, but little is known about the biodiversity underground. Eawag researchers have now documented the diversity of life in Swiss groundwater in a pilot study – and discovered previously unknown species of amphipods in the process. Here they relied on a citizen science approach.

Formerly widespread, native crayfish in Switzerland are now highly endangered. With support from Eawag, experts are doing everything they can to preserve the secretive river dwellers.

22 May is the International Day for Biological Diversity. In 2021, the theme is: "We are part of the solution". The research institutes Eawag and WSL are working together in search of solutions to conserve, promote and protect biodiversity.

The influence of various factors on the ecosystem of Lake Constance and its resilience is the main focus of two mutually informative and wide-ranging research projects that are currently in progress.

In the Blue-Green Biodiversity research initiative of WSL and Eawag scientists from around the world are working together to find solutions to the pressing challenges of biodiversity loss. The scientists explain in a video what they are working on – and why.

The motto of today’s World Water Day is “Valuing water – What means water to you?”. With this motto, the United Nations wants to raise awareness of the vital importance of water and call on people to think about the value of water. In an interview, Eawag Director Janet Hering explains the importance of water for the aquatic research institute Eawag and also her personally.

There will be no general shortage, but water may be scarce depending on the region and time of year – conversely, heavier rainfall will lead to more local flooding. These are the findings of the Hydro-CH2018 project published today, Hydrological Principles of Climate Change. The extensive study with collaboration of the Eawag Water Research Institute was carried out under the lead of the Federal Office for the Environment (FOEN) in conjunction with the National Centre for Climate Services (NCCS). Climate change means that our use of water will have to change in future.

In Lake Constance, sticklebacks are occupying increasingly varied habitat types – in recent years even including the open and deep waters of the lake. In an Eawag review undertaken as part of the “SeeWandel” project, these uniquely diverse ecological adaptations are explained in terms of renewed contact between three stickleback lineages – including one originating from the Baltic region, whose genetic material is as yet rarely observed in other Swiss lakes.

Copepods (minute crustaceans with paddle-like feet) can differentiate between disturbances in water generated by nearby organisms and turbulence caused by wind or waves – an ability which helps them to find mates. It had previously been assumed that turbulent conditions would impede the quest for mates.

Beavers are master builders that reshape aquatic landscapes with their dams and lodges. The environments they inhabit experience an increase in the biodiversity of aquatic organisms, for example. Now, for the first time, an Eawag study from the wine-growing region known as “Zürcher Weinland” has shown that this is also true for streams in areas given over largely to agriculture. The rodents could therefore be interesting partners when it comes to enhancing bodies of water.

Europe still has barely any downstream passage facilities that guide fish past the turbines of run-of-river power stations unharmed. Now, an interdisciplinary team of engineers from ETH Zurich and fish biologists from Eawag have developed a rack that uses pressure and flow differences to guide fish out of the main flow and into the safe fish passage. Laboratory tests have shown that the system, which works by influencing fish behaviour, is particularly effective for cyprinid fish and salmon parr.

The analysis of DNA fragments and their assignment to individual species – an increasingly well‑established approach – is transforming biodiversity assessment. Samples collected from waterbodies permit rapid biomonitoring of aquatic ecosystems. However, environmental DNA (eDNA) analysis is not without pitfalls. For this reason, guidelines for practitioners have now been developed by a group of experts – including Eawag scientists – coordinated by the Federal Office for the Environment. These guidelines, covering the whole process from sampling to data interpretation, should help to ensure that eDNA applications produce reliable results.

A factsheet from the Swiss Academy of Sciences (SCNAT) shows: Too much nitrogen and phosphorus is released into the Swiss environment. There they damage biodiversity, forests and water bodies, exacerbate climate change and affect human health. Actually the causes are known.

Exploration and utilisation of resources from the world’s oceans is not equally distributed across the globe. Although many of these resources originate in the Global South, they are mostly being researched by just a few countries from the North. Accordingly, this is also where most of the benefits and profits are flowing to, despite the Convention on Biological Diversity. This was the finding of an analysis of literature from the last 50 years.

Whether a lake was once polluted with excess nutrients is reflected even decades later in the community of bacteria living on these nutrients in the sediment. However, there is still surprisingly little research into how microbes in the sediment cooperate.

Until recently, researchers assumed that Switzerland had around 20 native species of amphipods. Now, a project by the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and the University of Zurich has revealed that there are actually more than 40. It is always worth taking a closer look, because we can only protect the things that we know exist.

Process Engineer Adriano Joss from Eawag water research institute has been working for many years on wastewater treatment plants and the removal of micropollutants from water. Together with Ralf Kägi, Head of the Eawag Particle Laboratory, he has compiled the current status of knowledge on microplastics. In an interview, he presents the most important findings. We have recently posted detailed information on the website “Microplastics in the environment”.

Using genomic analyses of 100 cichlid species, scientists from Eawag and the University Bern, together with co-workers in Australia, the UK, Tanzania, Uganda and the US, have investigated the striking variation observed in cichlid fish speciation rates. Their findings show that exchanges of genetic variants between existing species dramatically accelerate the development of new species – given favourable ecological conditions.

Blue-green algae are very common both in the water and on land. Sporadically, they occur in lakes on the surface in such large numbers that one speaks of a bloom. Because there are species that can produce toxic substances, many questions arise.

Biodiversity and thus the state of river ecosystems can now be predicted. To achieve this, researchers from the University of Zurich and Eawag (Aquatic Science and Technology) are combining environmental DNA with hydrological methods. Using the river Thur as an example, the approach allows identifying target areas for conservation and initiating protective measures.

The Verband zum Schutz des Greifensees (VGS) (Association for the Preservation of Lake Greifensee) elected its new Council of Delegates on 25 June 2020. In addition to representatives of all municipalities surrounding the lake, the committee also includes cantonal agencies, farmers, fishermen, sailors and – for the first time – a research representative, with the election of Eawag’s Piet Spaak as an aquatic ecologist.

Natural environments vary in space and time and are now drastically changing due to human activities. Environmental changes, like increasing acidity in a pond, can strongly affect the long-term prospects of species. Katja Räsänen from Eawag’s department Aquatic Ecology aims to understand how natural populations of the moor frog adapt to environmental change.

Since spring 2018, the newly developed underwater camera Aquascope has been recording a wide variety of plankton species in Lake Greifen. These sensitive organisms can thus, for the first time, be observed undisturbed in their natural habitat – an important step towards automated monitoring of water quality and aquatic biodiversity.

If one observes the competition between parasites and symbionts, much can be learned about the theory of evolution. Two Eawag researchers have thus shown in a new study that high parasite diversity promotes symbiont diversity.

126 Swiss researchers, including 6 from Eawag, want to draw the attention their Swiss compatriots to the scientific evidence showing the link between the emergence of pandemics and human disturbance of the natural environment.

To mark this year’s International Day for Biological Diversity on 22 May, professor Catherine Graham and professor Florian Altermatt explain in an interview why it is important in biodiversity research to look beyond systemic boundaries. The two scientists lead the joint research initiative “Blue-Green Biodiversity” between WSL and Eawag.

To protect ecosystems, it is important to understand how environmental disturbances, such as forest fires or hurricanes, affect nature. A study by Eawag and the University of Zurich now shows how their frequency and intensity affect small and large organisms. Accordingly, large species are more affected by disturbances than small species, and this influences the size distribution within ecological communities.

The spatial requirements for surface waters specified in the Waters Protection Act represent the absolute minimum required to safeguard their ecological functions. The space provided along small streams is of particular importance, as material flows between terrestrial and aquatic ecosystems are not dependent on the width of the watercourse. This is shown by Eawag’s own investigations – and by a review of available studies, which was cited by the Federal Supreme Court in a recent ruling.

The ETH Board is strengthening the interdisciplinary biodiversity research of WSL and Eawag in order to find answers to the urgent social challenges of species loss as quickly as possible.

Host and parasites are often engaged in an evolutionary arms race. Researchers at Eawag have intervened in this warring relationship and demonstrated how it can be used to improve biological pest control.