Farewell Klaas Timmermans | Algae, mosquito larvae or seaweed: what do they need to be happy?

Department

Estuarine & Delta Systems

Themes

11 Mar 2026

Seaweed researcher Klaas Timmermans has a remarkably down-to-earth view of his research subject. He also finds algae and midge larvae interesting. After 35 years at NIOZ – on Texel and in Yerseke, as a scientist and as a manager – he is bidding farewell with a symposium on 9 April 2026.

He presented King Willem-Alexander with a slippery piece of seaweed when he came to open the Seaweed Centre on Texel in 2014. As an algae researcher, he went on ocean expeditions, supervised young researchers and managed four NIOZ departments. With satisfaction biologist Klaas Timmermans looks back on an interesting and varied career.

Always fascinated

‘As an ecophysiologist, my focus is on the conditions organisms needs to thrive. That has always fascinated me. Which organism I study is less important to me.’ Timmermans is best known as a seaweed researcher, but during his first twenty years at NIOZ he conducted research on algae and, before that, as a PhD student, on midge larvae.

Timmermans experimented with temperature, light and nutrient conditions and discovered, for example, that the biotic environment surrounding an organism also has an influence. ‘Seaweeds reproduce by means of spores. These grow into gametophytes: carriers of the sex cells. These gametophytes seem to “know” how many there are. If there are too many, the gametophytes do not reproduce, even if all conditions are favourable.’ Timmermans has contributed greatly to our knowledge of what constitutes good conditions for aquatic organisms. ‘I thought: I can find that in the literature. But it took a lot of experimentation and fieldwork.’

Cow feed or food

In the video Sea of Knowledge

, Timmermans can be seen supervising PhD candidate Jesse van Groenigen, who is working on seaweed in Yerseke. Thanks to the facilities of the Seaweed Centre, partly on Texel and partly in Yerseke, researchers always have access to seaweed and can conduct experiments with it under all kinds of conditions. This is very convenient now that so many eyes are focused on the opportunities that seaweed seems to offer for sustainability and health.

Timmermans, who is also Professor of Marine Plant Biomass at the University of Groningen, is not susceptible to hype. Correspondent journalist Tamar Stelling interviewed him

last year about the many enticing possibilities of seaweed. From cow feed (which reduces methane emissions) to bales of captured carbon to be buried in the deep sea (immoral, according to Timmermans). “I'm more of a nuance kind of person, the researcher said to Stelling. He would prefer to see people eating seaweed, a sustainable source of high-quality protein. But whether that will happen on a large scale any time soon: ‘Haha, well... Do you have a few hours? Everything about this is still in its infancy.’

From professional knowledge to strategic goals

It was due to tragic circumstances that Timmermans ended up in management positions. ‘When our department head Wim van Raaphorst died in an accident in the 1990s, I became interim head of the Marine Chemistry and Geology department.’ Later, Timmermans became head of the Biological Oceanography department, and when that department was to be closed down, he planned to return to science in 2015. ‘But then Henk Brinkhuis called to ask if I wanted to become head of department in Yerseke.’ In 2020, Klaas also served as interim head of department at NIOZ Texel in the Coastal Systems department for eight months.

From his home in Alkmaar, Timmermans arranged for a houseboat in Zeeland, where he has been staying every week for the past ten years. ‘During one period, I was more involved in my profession, in which I was later able to supervise PhD students and postdocs. During the other period as a manager, it was nice to work on more strategic goals. Such as keeping the NIOZ branch in Yerseke open and successfully anchoring it in Zeeland, and participating in the Delta Climate Centre

.’

It's been well enough

Last year, Timmermans handed over his duties as department head to Andrew Hirst. ‘People asked me, “Isn't that a bit early, Klaas?” I look back on a marvellous time at NIOZ, but now I think it's been well enough.’ The houseboat will become a holiday home.

Invitation Retirement symposium Klaas Timmermans

9th April 2026 | NIOZ Yerseke | 14.00-18.30

Registration: Registration form for Klaas Timmermans farewellsymposium

Klaas Timmermans holds a bundle of seaweed

Klaas Timmermans in the Seaweed Centre. (credit: NIOZ)

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