Macroalgae

The SUBMARINER Network is a partner in the GRASS project - Growing Algae Sustainably in the Baltic Sea. Through capacity building and awareness raising, GRASS will result in a demand for macroalgae and unlock the potential of macroalgae production and application sectors in the Baltic Sea Region. This webpage presents the key facts, reports, networks and other relevant information on macro-algae in the Baltic Sea.

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About Macroalgae

As a result of eutrophication, the amount of macroalgae throughout the Baltic Sea has increased. Precise figures are missing due to lack of monitoring, but especially in South Sweden and Denmark substantial amounts of beach wrack assemblages in the range of 70,000–85,000 tons of dry weight per year can be found. Whereas it is difficult to use them readily as fertilizers on agricultural land due to the risk of high-level metal content, there are promising results of pilot studies carried out in using macroalgae as a part of locally available biomass resource mix for biogas plants).

Also, intensive aquaculture of Baltic macroalgae can provide for an important food and feed source, but also a valuable resource for ingredients, materials and energy. Brown and red algae species can grow inside the proper providing ecosystem services, by reducing the nutrient load and combatting climate change by fixing CO2 in biomass.

Food

Macroalgae may be used for human consumption and is a healthy nutritional source: edible macroalgae have high water content, are low in calories and rich in vitamins and minerals. Some species are high in digestible proteins (20–25 % protein of wet weight) and the fibre content is usually higher than in terrestrial plants. Brown and red algae species are mainly used. The brown macroalga Laminaria japonica (know as kombu) is particularly popular. Moreover, the brown alga Undaria sp. (known as wakame) and the red alga Phorphyra sp. (known as nori) are economically important macroalgae species for human consumption. The interest in Asian food in Europe and the Baltic Sea Region has increased during the last decade but the use of macroalgae as food is still a small business. Source

Feed

Macroalgae are also often used as an additives to animal feed due to their high content of minerals, trace elements and vitamins. Brown macroalgae are most frequently used for this purpose. Some species of red macroalgae have been reported having very promising beneficial properties connected with reducing the methane production of livestock. Source

Fertilisers

Macroalgae are used as fertilisers worldwide, as they not only contain nutrients such as nitrogen, phosphorus and potassium but also trace elements, vitamins and hormones and other compounds that act as soil amendments and promote plant growth. Large brown algae are most commonly used but others can be used as well. In the Baltic Sea there is a risk of high metal content in macroalgae due to a combination of high metal concentrations and low salinity in the waters. Macroalgae from the southern part of Sweden and Denmark generally have high contents of cadmium and thus macroalgae fertilisers cannot be used on land. There is no common EU -directive on cadmium content in biofertiliser and the regulations are different between the countries in the Baltic Sea Region. In Sweden, there is legislation about how much heavy metals that are allowed to be put on arable land. There are also certification systems with recommended limiting values for cadmium content in the biofertiliser. These are two factors preventing biofertilisers with high cadmium content to be attractive on the Swedish market. A cost-effective technique for cadmium purification is still not available although research is in progress. In other parts of the Baltic Sea where cadmium content is lower, such as in Poland, macroalgae digestate can be used directly without further treatment.

High-value compounds

Macro-algae contain many useful substances such as antioxidants, pigments, enzymes and polyunsaturated fatty acids, which can be used in the biochemical industry for drugs, cosmetics and dietary supplements. These substances may have a high value on the market. Another important and profitable global market is the extraction of substances from macroalgae, such as phycocolloids. These are natural products that serve to stabilise commonly used emulsions and dispersions in a large number of applications such as diary products, leather, textiles, cosmetics and pharmaceuticals. In 2009, a total of 86,000 tonnes of phycocolloids were sold, with an estimated value of approximately € 0.75 billion.16 Brown macroalgae species of the genera Ascophyllum, Durvillae, Eclonia, Laminaria, Microcystis, and Sargassum are used for alginate extraction. Gelidium sp. and Gracilaria sp. are the two main red algae genera containing agar colloids.

Gelling agents

Another important and profitable global market is the extraction of substances from macroalgae, such as phycocolloids. These are natural products that serve to stabilise commonly used emulsions and dispersions in a large number of applications such as diary products, leather, textiles, cosmetics and pharmaceuticals. In 2009, a total of 86,000 tonnes of phycocolloids were sold, with an estimated value of approximately € 0.75 billion.16 Brown macroalgae species of the genera Ascophyllum, Durvillae, Eclonia, Laminaria, Microcystis, and Sargassumare used for alginate extraction. Gelidium sp. and Gracilaria sp. are the two main red algae genera containing agar colloids.

Other commodity and fine chemicals

In addition to the hydrocolloids described above, macroalgae also contain other useful substances such as antioxidants, pigments, enzymes and polyunsaturated fatty acids, which can be used in the biochemical industry for drugs, cosmetics and dietary supplements. These substances may have a high value on the market.

Biomaterials

Macroalgae species are rich in carbohydrates which can be converted to biopolymers, similar to starch and lignocellulosic biomass resources in agriculture. Macroalgae are for several decades used for extracting hydrocolloid materials such as agar and carrageenan. Hydrocolloids are used in food applications to influence texture or viscosity (e.g., a sauce). Also, hydrocolloid-based medical dressings are used for skin and wound treatment.

Also, Polyhydroxyalkanoates (PHAs) is a class of biodegradable bioplastics which are considered to be feasible replacements for current petroleum-based plastics. PHAs have properties similar to oil-derived polypropylene and polyesters.

As macroalgae bioplastics are getting into the spotlight of many R&D projects, it is expected that more materials and blends will appear in the market in the next years to come.

Biogas production from beach wrack

Shortages in biomass available for bioenergy production have increased the interest on the use of macroalgae. Macroalgae are typically high-moisture material (80–90 %) and are considered to be more suitable for aqueous processing techniques such as anaerobic digestion or fermentation carried out by microorganisms. Anaerobic digestion uses anaerobic bacteria to breakdown or “digest” organic material in the absence of oxygen. Biogas can be used mainly for the generation of electricity and/or heat, or used as fuel in the transport sector. Biogas for use as fuel needs to be upgraded to methane. Two of the main advantages of using macroalgae in biological processes compared with other material are the high-water content, which can be mixed with dryer material, and the fact that macroalgal cell walls do not contain large quantities of hard materials such as lignin and cellulose that are difficult for microorganisms to break down. Some of the disadvantages of using macroalgae are the presence of salt, polyphenols in brown algae and sulphated polysaccharides, all of which can inhibit biological processes if not properly managed. However, algae produced in brackish or fresh waters contains low salt. Many pilot projects on biogas production from macroalgae are currently being realised in the Baltic Sea Region, including some focusing on the biochemical processes of anaerobic digestion. Two of these examples, from the Trelleborg (Sweden) and Solrød (Denmark) municipalities are worth highlighting. Notably Coastal Biogas and CONTRA projects are testing anaerobic digestion of macroalgae beachwrack.

Nutrient uptake

Studies on the potential of Baltic macroalgae show that nitrogen content is around 2–6 % of the algae dry weight,17-20 which is less than that of blue mussels. The phosphorus content in macroalgae is usually less than ten times lower than the nitrogen content. However, under certain local conditions in which substantial biomass is available, the effect of nutrient removal can still be quite substantial.

Meet the Baltic Macroalgae Community