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Why we need algae

16 May 2018

Algae researchers Maria van Leeuwe and Jacqueline Stefels poured hundreds of litres of seawater through their filters as they sailed from the Bahamas to Ireland, last April. This was on a leg of the Netherlands Initiative Changing Oceans (NICO) expedition on the Pelagia research ship. The aim of NICO is to improve our understanding of the opportunities and threats to our changing oceans.

Text Fenneke Colstee

If you walk past a yellowish-white foam on the beach, you may not be aware that it is the remains of a colony of microscopically small but certainly not insignificant algae. They belong to the ‘flagellates’, which together with the other single-celled diatoms form the basis of the food chain in the sea. The flagellates also produce a gas that encourages cloud formation and could thus delay global warming. This could even mean a difference of several degrees. Jacqueline Stefels and Maria van Leeuwe are trying to discover more about how, when and where this gas is released and in which quantities.

Jacqueline Stefels
Jacqueline Stefels


Van Leeuwe and Stefels have clearly fallen hook, line and sinker for microalgae. Not just because they are fantastically beautiful under a microscope but because of the surprisingly significant role that they play in the oceans and on earth. The pair travel all round the world for their research. They have already notched up five two-month stays in Antarctica, where there has been a Dutch research base since 2012. And when last autumn they were invited to join the Bahamas-Ireland leg of the NICO expedition in April they soon agreed. It does make it easier that they are not just UG research partners but life partners too. They got to know each other in the algae world and both hold doctorates in biology, although Stefels studied and did her PhD at the University of Amsterdam (UvA) and Van Leeuwe at the University of Groningen.

No goldmine

When it comes to grants, fundamental algae research is definitely no goldmine, the two grumble. ‘People don’t really want to know all about the small stuff underwater. They much prefer birds.’ Stefels once submitted an excellent research proposal to NWO, says Van Leeuwe, but it was rejected by the civil servants at the Ministry of Economic Affairs because it was not about CO2 but about DMS or dimethyl sulphide. And although we all know the fantastic smell of the sea that it causes, this sulphurous gas is neglected in climate research, despite being very important to the climate. It works like this: once it escapes from the sea, DMS is converted into sulphate, which causes water molecules to form droplets, which results in a cloud. And clouds keep out the sun’s rays, which means the earth does not warm as much. Strangely enough, smog also has this ‘cooling’ effect, so air pollution has long masked the greenhouse effect of CO2 .

Maria van Leeuwe, working at the Pelagia
Maria van Leeuwe, working at the Pelagia


To emphasize in the battle for grants the societal impact of their research, biologists like to point to the ‘ecosystem services’ that their research object can provide for society. Van Leeuwe and Stefels are well-versed on these. Algae produce a lot of oxygen, even as much as woods, land plants and ancient forests combined. They are also responsible for about half of the CO2 absorbed from the atmosphere. In addition, as food they support enormous biodiversity. Without algae there would be no jellyfish, crabs, herrings, whale or gulls. And it speaks for itself that great biodiversity in a healthy ecosystem is useful to the fishing industry. A better picture is also emerging of what the marine ecosystem does for the climate. A familiar example is the CO2 that diatoms store and take, together with their improbably beautiful glass shells, to their watery graves on the seabed, thus forever locking it away from the atmosphere. The DMS-producing flagellates also deserve a mention here, say Stefels and Van Leeuwe. They hope that their trip across the Atlantic Ocean will improve our knowledge and appreciation of algae, thus netting more information on why we need algae.

Spoilt in Antarctica

As DMS consists of dimethyl sulfoniopropionate (DMSP), which is released by algae, Stefels and Van Leeuwe are researching which conditions cause algae to produce more or less DMSP. (DMSP prevents salt stress by regulating the salt content in the single-celled alga.) On the trip from the subtropical Bahamas, where the water temperature was 22 °C, to Galway in Ireland, where it was 12 °C by the coast, they harvested algae at different depths in nine places. That was not always easy. They had to filter many litres of seawater to gain an acceptable quantity of algae. They realized on the Pelagia how spoilt they had been in Antarctica, where the cold seawater contains so much more algae and has infinitely more species of particular interest to Van Leeuwe, who researches the diversity of algae species.

Lng-finned pilot whales jumping alongside the boat
Lng-finned pilot whales jumping alongside the boat

Pressure cooker

The researchers hope to discover the circumstances under which algae put their energy into growth or producing DMSP. They therefore already began to study the growth of the harvested algae on the Pelagia, in large basins of seawater. Back in Groningen they will now try to draw conclusions from all the data that they collected. How do they look back on the expedition? ‘It was three weeks of hard work. We did the first filtration at five in the morning and finished at ten at night. But luckily we had fantastic food every day. Hassan, the cook from Groningen, is an amazing cook. The collaboration with colleagues from other universities, like the UvA, was also very important. On land you tend not to seek out each other’s company you’re competitors after all. But a small ship with about 20 researchers really is a pressure cooker for academic relations.’


However fundamental their research may be, they always keep an ecologist’s eye on the relationship with the world around them, with the dolphins and seabirds. ‘One day we saw surprisingly few birds. We immediately brought up very little algae.’ And the ocean? They never tire of it. ‘To be on that small ship with the waves, the skies – it’s amazing! Sometimes long-finned pilot whales jump alongside the boat or you see northern gannets or a Portuguese man o’ war...’ But finally getting to drink a beer in an Irish pub after three weeks at sea wasn’t so bad either. Even without foam.

Last modified:12 March 2020 9.23 p.m.
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