RTG2530 short portraitsWelcome to the team, Arne Malzahn!

8 December 2025, by RTG2530

Photo: UHH/RTG2530/Latos

We are delighted that Arne Malzahn has joined the RTG2530 team as a new ‘Principal Investigator’. To introduce him briefly, we asked him three questions.

1. What is the main focus of your research, and what are the overarching topics, questions or objectives?

In the RTG2530, my research currently focuses on the aquatic part of the Elbe estuary. I am particularly interested in how planktonic animals – i.e. animal organisms floating freely in the water – react to environmental changes in the Elbe and how these reactions affect growth and reproduction, for example. This raises questions such as: Are there groups of animals that can cope better with warming than others? How does this influence food webs? Do shifts in species composition lead to changes in the carbon cycle of the Elbe? In the end, I hope to contribute a small piece to the mosaic of understanding how the Lower Elbe functions.

2. What made you decide in favour of this field of research? What fascinates you about it, and what do you see as the biggest challenge?

I have always been interested in food-web interactions. I originally come from the fish side of things, but early on I realised that small planktonic crustaceans play a major role as food for fish and are therefore particularly intriguing for Fischköppe like me (a self-ironic northern German nickname, often used for people from the coast). Under what conditions are there many planktonic crustaceans – in other words, how much fish food is available and why? How does the biochemical composition of these little crustaceans change in response to shifting environmental conditions – that is, how does the quality of fish food change, and what drives these changes? The major challenge lies in the dynamic nature of aquatic systems, especially in flowing waters such as the Elbe, where conditions can shift dramatically within short periods of time – and in the sheer size of these systems. Am I actually looking at the right moment? Are the organisms I am studying and their food currently in the same place, or are the fish somewhere else entirely? And finally: how can I draw conclusions about the bigger picture from small-scale investigations?

3. What are your expectations of the collaboration in the Research Training Group 2530, and is there anything you are particularly looking forward to?

The Research Training Group gives me the opportunity to work closely with colleagues from a range of research fields and to draw inspiration from their perspectives and ways of thinking. Furthermore, interacting with many doctoral researchers offers an exciting chance to observe scientific development processes first-hand and to see young people outgrow themselves.