The changing tides of agriculture: How seaweeds help to shape a greener future

Cover story of the Swedish popular science journal, Havsutsikt

I am more than happy to contribute the front-page story of this year´s issue of the Havsutsikt´s journal. The journal Havsutsikt functions as an important bridge between the research world of Marine Sciences and the broad public and thus successfully transmits and communicates latest research results to the society. With more than 12 000 printed copies and the possibility to access the articles also in a digital format, the journal offers a barrier-free and easily accessible way to obtain latest information on Marine Sciences all across Sweden.

You can read the Swedish article here, or the English translation below:

Algae pave the way to a greener future

The waves of the Koster fjord gently roll against the boat. On this early morning in February it is -7 °C, the air is still freezing cold from the Scandinavian winter and the fjords in the Koster Archipelago are partially frozen. “Our seaweeds can cope perfectly fine with this cold weather conditions and they are now starting to grow even better when the days are getting longer”, says Sophie Steinhagen, (Phycologist [algae researcher] at the Tjärnö Marine Laboratory – University of Gothenburg) full of joy while holding some young, emerald green seaweeds in her hands.

“Maybe you’re only familiar with seaweeds as the slimy masses left on the beach after high tide. What you will know after reading this article is, that what tickled you at the feet while taking a swim in the ocean last summer was the future potential of seaweeds that I am trying to unlock with my research”.

Seaweeds provide vital habitats for invertebrates and are important nursery grounds for fish. These oceanic gardens constitute indispensable and unique ecosystem services that are not only vital for our ocean´s health but also on an even larger scale, for example by playing a major role in the planet’s carbon cycle with their effective sequestering power. And as if this would not be enough, seaweeds gain increasing interest from an industrial perspective due to their various bioactive and universally applicable compounds.

Off the coast, beneath the turquoise blue waves of the Swedish west coast, a renewable resource swings gently with the tide: Sea Lettuce, a green seaweed, grows within the seafarm from ropes that are kept at place by buoys that just reach above the water surface. “Our Sea Lettuce which is scientifically known under the name Ulva gets planted in late fall, grows throughout the Scandinavian winter and is harvested in late spring”, tells Sophie.

Today, Sophie set out with her colleague Gunnar Cervin to control the growth of her experiment that is focusing on cultivating Sea Lettuces in Swedens biggest seaweed farm. The successful large-scale cultivation of Swedish Sea Lettuces was tested in an interdisciplinary research project among the University of Gothenburg, Chalmers University of Technology and KTH with the goal to find sustainable and renewable resources to contribute to a better future.

Especially the fast growing seaweeds may hold the answer to the major questions the earth´s population is facing right at the moment. For example: how can we expand agricultural production when terrestrial space is getting scarce? How can we sustainably exploit new, resources to end the prevailing resource scarcity? And, how can we feed a growing world population?

Seaweeds do not compete with other crops for arable land or fresh water and furthermore they can extract nutrients from our oceans and are thus not depending on fertilizers. This simultaneously contributes a bioremediation effect of the cultivated seaweeds to our pressured oceans. The seaweeds take up nutrients, such as nitrogen and carbon from the eutrophied oceans and transform the nutrients into a new biomass resource.

Based on scientific studies, seaweed aquaculture is considered the most sustainable form of any aquaculture and the multi-purpose use of seaweed biomass in different industrial sectors could make seaweeds an important cornerstone in a greener future.

The Sea Lettuce cultivated in the Koster fjord can be used in different branches says Sophie: “With our experiment we can not only show that it is possible to grow Sea Lettuces in a large industrial scale in Swedish waters but we furthermore confirm that the biomass can be used in different important economic sectors. Its compounds can be applied as source material for pharmaceutical commodities, as innovative building material and with its suitable protein and fatty acid content as healthy future food.”

Particularly as a food source, marine seaweeds have a very old tradition in Asia and with her research Sophie Steinhagen and her colleagues can show that this food source is on its way for a sustainable exploitation in Sweden as well. “Together with our colleague João Trigo from Chalmers University of Technology, we are for example testing the availability and human digestion potential of proteins derived from Sea Lettuces and our results are very positive that Swedish Sea Lettuces are nutritious and healthy.”  

Whereas some of us would appreciate a salty bite of a healthy green Sea Lettuce the scientists are also investigating methods to extract the proteins from the seaweeds to enable their use in e.g. protein burgers, shakes or bars to also address people that are hesitant towards eating seaweed in its “raw” form. Hence, by providing a solution of using Sea Lettuces on different levels as a food source the researchers aim to pave the way towards the ecofriendly exploitation of vegan protein sources that are urgently needed for ourselves and the earth´s well-being.

A point of utmost importance are the relatively high labour costs which afford a mechanization of wide parts of seaweed aquaculture and this has to be accompanied by the upscaling of seaweed production to reach biomass yields beyond laboratory or pilot scale. A way to improve the Swedish seaweed aquaculture sector is the selection of suitable and fruitful species, which flourish under Scandinavian conditions.

“As a researcher I am are interested in exploring the Swedish seaweed biodiversity and making use of natively occurring Sea Lettuce species by quantifying their cultivation potential which may vary among different species”. The green Sea Lettuces are widely distributed and can be found along nearly the whole coastline of Sweden – from the fully marine rocky shores of the Swedish west coast up to the sandy beaches of the low salinity exhibiting Baltic Sea coasts. Therefore, Sea Lettuces are “all-rounders” which can cope with varying and fluctuating environmental conditions.

This opportunistic ability of adapting to different ecosystems imparts the Sea Lettuces a geographically wide area of application. This for example makes them especially interesting as a crop that could be cultivated in the Baltic Sea region of Sweden. “I am interested how many species of green seaweeds we have in Sweden, how they differ in their potential as future commodity for example by testing their biochemical profiles and if there are differences in the best cultivation methods of different species”. To test the aquaculture potential of different seaweed species the Tjärnö Marine Laboratory offers a greenhouse to cultivate the seaweeds on shore. “Our seaweed greenhouse functions as a conventional green house for your tomatoes or cucumbers. We can set the best conditions to cultivate our seaweeds but also manipulate factors to see how the seaweed reacts on them”, explains Sophie. In the greenhouse the researchers can change the temperature, light intensity or nutrient addition which enables them to characterize the seaweed performance under varying conditions. This helps to evaluate what are the best factors to provide good biomass yields or an increase of desired traits, e.g. high protein amounts for the best nutrition level.

“For me it is the multifaceted possibilities seaweed can bring to the Swedish and global society and industry by concomitantly restore our natures batteries. It is a matter of how we want to change and shape our own and our children´s future and I am convinced that seaweeds can help to pave the way towards a more responsible, sustainable, and greener future”.

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