Angelina Tittmann

"We are looking at the bigger picture of biodiversity"

An interview with Sonja Jähnig
Professor Dr Sonja Jähnig has been appointed Head of Department at IGB. The topics of the newly created department entitled "Community and Ecosystem Ecology" could hardly be more relevant: Jähnig and her colleagues conduct research on aquatic biodiversity, on the services that freshwater ecosystems provide to humans, and on the impacts of global change. In an interview, the professor talks about her personal goals, what each of us really should know about rivers and lakes, and why freshwaters are often overlooked.

© David Ausserhofer/IGB

Ms Jähnig, you have just been heading the new Department of Community and Ecosystem Ecology at IGB since January. What are your first impressions?

I am very happy, but my new tasks are also a challenge. So far, I have mainly worked in science. Research is still important to me, but I assume that this area will become less of focus now. I consider it a challenge to balance this well.

What swayed your decision?

The task itself interested and fascinated me. To be involved in the development of the institute or to have the opportunity to push a certain topic is very exciting to me. In addition, I am very much looking forward to the exchange and cooperation with the other departments.

Which topic do you particularly have in mind?

There are two: I would like to further expand data management. Data are an important anchor for cooperation within and outside the institute – but to fulfil this it should be available, findable and well documented. IGB has already built up very good structures to make data available in this way – but these need to be exploited even more. Overall, we need a real rethink in research: data should not be perceived as property, but as something that creates added value if many people can use it. Of course, this requires effort, but in the future this effort should be understood as a necessary but natural task. The second topic is the long-term programmes of IGB, where I feel we can make more use of this data resource. At present, they are strongly focused on the lakes, i.e. on Lake Stechlin and the Müggelsee. Of course, this should be continued. But I also see great potential in the comprehensive evaluation of the data sets. And I have the idea of adding an additional watercourse that takes into account the special characteristics of the north-east German lowlands.

What do you expect from this?

In contrast to other regions in Germany, there is a lack of long-term monitoring points in the LTER network in flowing waters here, which, for example, monitor trends in the drought-sensitive north-eastern part of Germany. Here I can very well imagine a stronger collaboration with IGB's Department of Ecohydrology and Biogeochemistry, which is already very active in this region.

The other departments also deal with issues of biodiversity, ecosystem services and environmental change. What is the role of your new department?

We are looking at the bigger picture of biodiversity in inland waters, which is where our potential lies. To this end, we work on very different groups of organisms: from tiny algae, which you initially only notice as a speck of colour in the water, to very large animals, so-called freshwater megafauna species – one of my personal research foci. We are also very much concerned with questions of water management, explicitly considering its application in our research.

Do you also derive a special mandate for political and social advice from your application-oriented research? 

Advising in the sense of informing and presenting facts: yes! For me, however, it also means inspiring fascination for the topic and sharing an exciting or surprising aspect with people that they perhaps didn't know or were aware of before. For many people, water is still primarily what comes out of the tap.

If it were up to you, what should everyone really know about freshwaters?

Everyone should turn over a stone at a more or less beautiful stream, ideally in spring, and be enchanted by the swarming and crawling organisms they see underneath it, tiny creatures that are so important, and of which many will be found later flying through the air as insects. Far too few people are aware of this intense connectivity between water, land and air.  

Is that where your own fascination comes from?

Not exactly, but it also comes from the aspect of connectivity; it has more to do with the fact that water flows. I grew up close to the Brigach, a tributary of the Danube – we played there a lot. When we built a dam, for example, I would imagine that there was no water left in the Danube. That wasn't possible, of course, but the idea that something I threw into the stream would then float through many places and countries fascinated me.

Meanwhile, you have two daughters of primary school age yourself. Do you have the impression that freshwaters have become part of the curriculum?

No, not at all. Mostly it's about marine animals. The fact that rivers flow into the sea and that many animals migrate back and forth between seas and inland waters or within water courses, for example, is completely missing. What is true for curricula is also often the case in environmental policy: everyone looks at the oceans and the land; inland waters are too seldom considered as independent and important systems, or they are mentioned only in passing in policies and documents.

Let's talk about environmental policy. What is often lacking in the conservation of water bodies and their biodiversity?

There is enough knowledge to achieve an improvement – it just has to be implemented consistently. Of course, there are still gaps in our knowledge, such as where exactly certain animals or plants occur, how common they are, and how their populations develop over time. This is still the case even with very large animals. And the smaller the animals are, the more difficult it becomes and the less we know about them. It is often almost impossible to recognise early on that something is wrong in the system.

You have been pointing out the silent crisis of biodiversity in inland waters for years. How do you assess the current discourse on the topic?

Let me give you an example: In late summer 2021, the topic was on the agenda of the Congress of the International Union for Conservation of Nature, or IUCN for short. There were countless sessions and workshops on freshwaters and their connectivity. Later, in the Marseille Manifesto, the connection to freshwater was only mentioned in passing. The topic was neglected once again.

And yet it is actually indisputable that water is the most precious good...

... but it is mainly perceived as a resource, as drinking water. The fact that entire ecosystems and habitats depend on it and that, conversely, the use of this resource also depends on its quality is not yet entrenched – and it is sometimes also difficult to substantiate these relationships with figures. And of course there are often conflicts of interest and use, especially in the case of water bodies. This is the big challenge that needs to be solved.

Since 2020, you have also been Professor of Aquatic Ecogeography at Humboldt-Universität zu Berlin. There, the Institute of Geography combines geographical issues with social, cultural and economic aspects, and does so in very different systems  from rural areas to metropolises, from the polar ice caps to our rivers and lakes. How does IGB’s research benefit from this integration?

This breadth is really unique! This cooperation gives us the opportunity to look at how freshwaters are embedded in the landscape in a complementary way. We can address the same questions, focusing on different systems, or jointly develop and carry out research projects. This gives us a better understanding of hydrological, biogeochemical, ecological and socio-economic processes, how ecosystems are interconnected, or how they respond to different stressors.

The Institute of Geography is also one of the oldest in Germany. When it was founded in 1887 and many decades later, women did not play a major role in science. Today, female scientists have their own research groups, head departments and chair institutes. Does this mean that women in science have reached their goal?

No, not at all – unfortunately. There is still a much lower percentage of women in higher career levels – starting at the postdoc level and getting worse at group leader level and above.

How do you explain this? Is it just a question of time or is it due to a structural problem?

There are often persistent structural and very complex problems behind this issue. Traditional role models play a part, e.g. the question of who relocates with whom when an opportunity arises and a job change is imminent; or whether childcare or other caregiving tasks can be equally distributed and supported by care structures; or certain behavioural patterns in day to day situations that have an impact on underrepresented groups overall; and because of the lower proportion of women, there are fewer role models and mentors who are able to inspire and support young female scientists.

Did you have such a role model?

When I had just started my undergraduate studies, Christiane Nüsslein-Volhard received the Nobel Prize in 1995. That deeply impressed me at the time. Since then, I have met many interesting personalities and built up a great network. Some of them have supported me a lot in my professional development, and are now role models for me.

What else helped you?

When I was offered the position in Berlin, my family came with me; and we had, and still have, very good family support for childcare, when needed. It has also been helpful for me to always have a Plan B. It gave me the feeling that if something didn't work out, I could still make a good living with my Plan B. So I had the courage to try things out – which went well, and that's how I moved forward, step by step.

Would you share this Plan B with us?

After I graduated, I spent two years in China funded by a DAAD scholarship. If my academic career had not worked out, I could have imagined working in business, for example, at the interface between China and Germany. But I am very glad that I became a scientist after all! Being able to find out new things or to analyse connections is what I find really exciting. In addition, you have great flexibility, independence and exchange, both near and far – which can probably not be found anywhere else to that degree.


Congratulations on the new role, Sonja! We are really looking forward to an active department that pushes relevant topics such as data management and long-term monitoring and at the same time inspires fascination for life in and at freshwaters!


About Sonja Jähnig:

Sonja Jähnig studied environmental sciences at the University of Duisburg-Essen, and spent one year at the University of Newcastle in Australia. Before embarking on an academic career, she went to Beijing for two years on a DAAD scholarship, where she first learned Chinese for a year and then coordinated a German-Chinese project on Beijing's sustainable water supply. Back in Germany, she received a doctoral scholarship from the Foundation of German Business (SDW) and did her PhD on river restoration. As a postdoc, she did research at the Institute of Hydrobiology of the Chinese Academy of Sciences in Wuhan for a year and then at the German Senckenberg Research Institute, exploring stream ecology and river modelling approaches. In 2010, she led her first junior research group at the Senckenberg Biodiversity and Climate Research Centre (BiK-F) and joined IGB as a research group leader in 2014.

Contact person

Sonja Jähnig

Head of Department
Research group
Aquatic Ecogeography

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