Can sus­tain­able kelp cul­ti­va­tion become a major industry?

A sharp upscaling of the kelp cultivation industry is on the way along the Norwegian coast. Can this be done in a sustainable way for marine ecosystems?

Products from macroalgae cultivation can become a comprehensive, global industry. These macroalgae can be used in food, medicine, health food and cosmetics, as biofuels and as substitutes for plastic products from fossil fuels. The algae have a number of other uses.

Calculations from SINTEF show that in 2050, as much as 20 million tonnes of kelp can be grown a year in Norway. In 2018, the national production was a modest 178 tonnes. The potential for cultivation is thus around one hundred thousand times greater than today's production.

If such a strong upscaling is to take place in a sustainable way, researchers need knowledge of the positive and negative effects industry can have on that ecosystem in the ocean.

Will an upscaling of kelp cultivation be positive for biodiversity along the coast? Can cultivation plants function as an artificial kelp forest? Or will new facilities promote the spread of alien and unwanted species?

- We try to answer these important questions, so that we can ensure sustainable management and contribute the knowledge needed for long-term planning of the kelp cultivation industry, Kasper Hancke explains. He is a researcher at the Norwegian Institute for Water Research (NIVA) and project manager for the research project KELPPRO.

- In this project, we have investigated where a kelp cultivation plant should be located for production and how the production affects biodiversity and the transport of nutrients and carbon in the sea, says Hancke.

Living conditions in artificial and natural kelp forest

A natural kelp forest is a complex ecosystem. These forests grow on mountains and large rocks down to about 30 meters deep. There, the species, the rich biodiversity, have adapted to life over a long period of time.

However, a kelp farm hangs in the sea only for a relatively short period of time. And only to cultivate more of one species.

To see what effects a kelp cultivation plant has on the marine ecosystem, researchers and students from NIVA have investigated whether the animal communities in such an artificial kelp forest reflect what is found in natural kelp forests. They have also investigated what the facilities mean for unwanted, endangered and vulnerable species.

Ragnhild Ryther Grimm Torstensen has written a master's thesis on the environmental effects of growing sugar kelp, as part of the KELPPRO project. The student did research on the kelp cultivation plant of Seaweed Solutions AS at Frøya outside Trondheim. She collected kelp in the plant and in the natural kelp forests around, under the guidance of Trine Bekkby, researcher at NIVA.

- We investigated, among other things, the effect of how long the kelp hangs out in the plant, to see if the growth period affects the kelp cultivation plant's ecological function, says Torstensen.

Findings show that the kelp cultivation plant has an ecological function as an artificial habitat during the period the kelp hangs in the plant.

At the same time, the study suggests that society is strongly influenced by what is found in the surrounding natural kelp forests - no matter what species of kelp this is. The time the kelp hangs out in the plant also has a meaning.

- The results from this study are very relevant to ensure sustainable management and good, long-term planning of the industry, both now and in the future with a potential upscaling, Torstensen explains.

Uninvited guests occupy the facility 

The empty facility, which hangs out all year round, even after the kelp is harvested in the spring, also had animal communities attached to it. This suggests that the plant may have an ecological function even after kelp harvesting.

The student and researchers found particularly large deposits of the alien species Japanese ghost shrimp on the ropes in the kelp farm in the autumn. They also found the species under piers in the area. Japanese ghost shrimp originally belong to the Pacific Ocean, and were first observed in Norway in 1999.

The researchers believe this is worrying, since this is a species that is placed in the category of very high risk in the Alien Species List. 

- It is due to its great invasion potential and ecological effect, says Trine Bekkby. She is a researcher at NIVA and has led this work. 

No Japanese ghost shrimp were found in the kelp farm in the spring, ie when there was still kelp in the farm. The researchers assume that one explanation may be that the algae at the plant blocked the ghost shrimp, which in any case thrive best under jetties and in algae that are in similar artificial places.

More knowledge needed 

The researchers have only investigated this one plant in the project. They have to look at several plants along the entire coast, under different environmental conditions, before they can come to conclusions that show what role kelp plants play in the sea. 

But already now the study shows that it is important to take into account a possible spread of alien species in an upscaling of the industry. The choice of materials and location will also be important. 

- If such facilities contribute to spreading competitive and dominant, unwanted species to natural habitats, the consequences can be great, says Trine Bekkby. 

- It is therefore necessary with more knowledge based on similar and new studies in the future to be able to provide a good basis for sustainable management of the industry, she says.

Translated from original article (in Norwegian):

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Facts about kelp and kelp cultivation
  • Macroalgae, including seaweed and kelp, are today an important resource in the world, but in the future will probably be a much larger source of both human and animal diets, as well as raw materials in other industries. 
  • The growth rate of macroalgae is potentially much faster than that found in terrestrial plants. No fresh water, pesticides or fertilizers are required during the production process. 
  • Increased use of algae can thus contribute to more sustainable resource production and help reduce the pressure on resources and land areas. 
  • The impact of kelp cultivation plants on the environment has been little studied. Introduction of man-made installations in the marine environment can have a number of negative effects. Studies of kelp facilities' environmental impacts are therefore an important contribution to the work to establish a knowledge-based management and planning of kelp cultivation along the Norwegian coast. 
  • The study discussed here was carried out at a kelp farm in Norway. In order to be able to generalize the results, it will therefore be important to carry out similar investigations at several kelp cultivation plants. 
  • The study was conducted at Niva, under the leadership of researcher Trine Bekkby, and in collaboration with the Department of Life Sciences at the University of Oslo. 
  • Want to know more about kelp, kelp farming and blue forest? Read more on the website of KELPPRO or in the "Blue Forest Week" which the researchers arrange 9-13. November.