Semi-structured interview notes



Short bio of Ole G. Mouritsen:

  • Professor Emeritus at the University of Copenhagen (KU) in the Department of Food Science. He is a physicist and professor of gastrophysics and culinary food innovation. He wrote a book called “Seaweeds: Edible, Available & Sustainable” in 2014 (both in Danish and translated in English).


Interview notes:


  • About eelgrass as seaweed:

“…Eelgrass is a plant; it is not seaweed. There are some Danish names that indicate it is a seaweed, but technically it is a sea plant; it has roots.”

“The eelgrass has been diminished in this part of Europe. There is not much left. There are certain parts of Denmark where there is more eelgrass than other places, but it has been devastated. There are a lot of animals that live in eelgrass that are dying, and of course, eelgrass also protects the bottom of the sea. In the old days, eelgrass what used for all sorts of things, like building materials and roofs.” “Eelgrass has sharp edges that make it difficult to be edible. There is probably potential to do something with it in the lab, but I think it is much better to use it for building materials.”


  • Possibility of growing seaweed in the coastal waters of East Jutland:

“Most of the places you are considering do not have the best substrate for seaweed. Seaweed requires mostly stone substrate. The other thing is that because of the change in salinity, it will be difficult to have one species that could survive the various different conditions because the different areas could have saltwater, and other times it could be freshwater or brackish water from the other side (rivers).

“Seaweed needs to be fixed; very few seaweeds do not need fixation. That is the way they get nutrients.”

“Middlefart is very deep, and you don’t have shallow waters there; it is some of the deepest parts because you have strong currents.”

“You don’t see the big brown seaweeds in the Danish coastline because they are out on the deeper water where you also have a rocky ground. Some people in the maritime garden try to get permission to dump stones on the bottom that could provide a substrate. The question is if you could bring something like that closer to land.”

“Before World War 2, there was a fairly large natural population of seaweed in Djursland that could thrive without being rooted. It was almost made extinct because it was over-harvested. But that was floating close to land and fairly shallow. The species is called Danish agar, Furcellaria (a genus of red macroalgae),”

“The areas where there is freshwater will lower the salinity and prevent seaweed from growing. You do not want the rainwater anywhere near the seaweed. There is also an issue with the circulation of water. Seaweed needs nutrients. Where you have the most seaweed is where you have the most “violent” water. You would have to be able to circulate the water.”

“There is no seaweed at the west coast because there are no rocks. And on the east coast, you have less flow of water. In Denmark, seaweeds are on the deep waters where you have the rocks, like in Kattegat. We don’t see them because we only have 30 cm of tidal variation. We only see a few species like bladderwrack (blæretang) near the coast.”

“Usually, it is said that there are more larger species of seaweed in colder waters.”


  • The role of maritime gardens in coastal cities:

“What is the objective of growing seaweed in more urban coastal areas? Is it for recreation, coastal protection, increased biodiversity, anti-pollution? Different objectives are not always mutually agreeable.”

“The maritime garden is a way to bring the ocean close to land, like gardening. It makes sense from an educational setting. One of the key ways of bringing people together is food. Seaweed is edible and acts as a way to create a culture around food.”

“Seaweed is not going to solve any issues on how much water comes into the city (sea level rise), but it could solve problems in relation to more sustainable food production.”

“Seaweed that is grown closer to the cities would be edible. The water needs to be tested. There is a maritime garden in Copenhagen where they grow blue mussels and oysters, so it is possible. When it comes to Vejle and Randers, you have the issue with rivers and a lot of nutrient-filled water.”

“Farming seaweed on a bigger scale (like in Kattegat), you have the benefit of capturing carbon dioxide.”

“To create an environment closer to the coast to accommodate seaweed, you need to create a lagoon, salinity, flow of water (nutrients), and stones.”

“There are a number of smaller seaweed species that are happy in the tidal belt. In Denmark, you wouldn’t find much more than bladderwrack, sea lettuce, and a few brown species, string algae etc.”


  • Seaweed as a beautiful entity:

“Many seaweed species have been used by artists in textile design, and they have different textures and shapes. They are considered beautiful.”