Macroalgae aquaculture needs to be expanded
This article was featured in Eurofish Magazine 3 2024
Many macroalgae (seaweed) and some of their constituent parts are edible. They are used as food and raw material for numerous products. Increasing demand is predominantly met by aquaculture. Around 35.1 million tonnes were produced worldwide in 2020, worth USD 16.6 billion. Now the EU has also recognized the potential of algae and wants to push forward production. The fact that algae are able to bind enormous amounts of CO2 contributes to climate protection.
There is evidence that humans were already consuming macroalgae 14,000 years ago, particularly in far eastern countries such as China, Vietnam, Thailand and Japan. Algae were also on the menu on some coasts in Europe, albeit to a modest extent. For example, the consumption of sea lettuce (Ulva lactuca) was widespread. In Italy, people used to enjoy Mauru seaweed (Chondracanthus teedei) seasoned with salt, pepper and lemon juice. On the Irish coast, algae is said to have once even been used as chewing tobacco. Back then, for understandable reasons, our ancestors could only use natural algae stocks, which in some places grew as real macroalgae forests. The area of these important maritime habitats is still considerable. Estimates of the area of global macroalgal biomes, dominated primarily by red algae, range from 6 to 12 million km2. Their extent is limited primarily by the sufficient availability of light on the seabed.
Today, however, only some of the macroalgae we use comes from wild stocks, as the demand is predominantly met by aquaculture. Based on the growth rates of the last few years, annual production is now likely to be around 40 million tonnes. The main producers are countries in South-east Asia, which contribute around 98% of the total production. In comparison, European algae production plays only a very small role that can hardly be represented in percentage terms. In addition, almost all of the algae produced in Europe currently come from natural sources. Although the level of theoretical knowledge about aquaculture in Europe is very high, there is a huge lack of implementation in practice. Algae aquaculture, long neglected, is still in its infancy, so to speak. That should now change if the EU Commission has its way. Macroalgae have become the focus of political attention, not least because of their ability to bind atmospheric carbon. As an effective tool for climate protection, macroalgae aquaculture positions itself perfectly in line with the EU’s Green Deal.
Neither animal nor plant
The term ‘algae’ is a collective name for living organisms with a true cell nucleus (eukaryotes) that live mainly in water and carry out photosynthesis. They are usually divided into microalgae and macroalgae based on their size. Microalgae are individual cells or cell chains that mostly float freely in the water as phytoplankton and are only visible under a microscope. Macroalgae, on the other hand, can be seen with the naked eye. According to their colour, they are usually divided into green (Chlorophyta), brown (Phaeophyceae) and red algae (Rhodophyta). Algae are neither animals nor plants, but form a separate group of plant-like organisms. However, not every ‘plant’ in water is an alga. Seagrass, for example, which locally forms extensive meadow-like areas on sandy seabeds, is a flowering plant.
Large algae or macroalgae play an extremely important role in coastal marine ecosystems as a food source and providing shelter and habitat for a variety of fish and invertebrates. Added to this is their economic importance for the food industry. Around twenty species of macroalgae are currently used commercially on a regular basis, either directly as food or indirectly as a source of protein and fibre as well as a gelling and thickening agent for industrial purposes. In the past, macroalgae were considered poor man’s food or were used as cold medicine, but today they have become a trendy product.
What makes macroalgae so popular, in addition to the many healthy ingredients, is their relative undemanding nature and enormous productivity. They grow almost anywhere where the light reaches deep enough into the water and they can cling to the seabed. Under good conditions, marine brown algae, especially species of the genus Laminaria, can reach lengths of up to 50 m or more and form veritable kelp forests, such as on the rocky coasts of Canada, Argentina, South Africa and Australia. The seaweed forests are not quite as lush off the European Atlantic coasts, but can grow into considerable bush landscapes wherever there is a sufficiently hard substrate available for settlement. Recently, humans have increasingly influenced the development of algae populations. Nutrient discharges from agriculture and industry (eutrophication effect) have noticeably changed the species spectrum and the amount of algae in many coastal areas.
Food and versatile raw material
The use of macroalgae for nutritional purposes is actually a matter of common sense, because they are actually a maritime superfood, a plant-based alternative to many conventional foods. Some species contain more fibre and magnesium than kale and more vitamins and minerals than most land plants. Algae are a sustainable source of protein that also contain antioxidants, omega-3 and 6 fatty acids and plenty of natural iodine as well as important trace elements such as zinc, iron, selenium, potassium and calcium. Their specific taste ranges from neutral to grassy to nutty. Wakame and sea lettuce taste slightly salty, while kelp varies from slightly sweet to fishy and spicy. Algae are particularly recommended for vegans as some species contain the vital vitamin B12, which is otherwise almost only found in animal products. Due to their pronounced umami taste and the content of fatty acids and trace elements, algae and algae extracts are also suitable as healthy flavour enhancers in meat and fish substitute products. Even the pharmaceutical industry is interested in some of the active ingredients in algae because they could potentially help with cancer, allergies and diabetes.
Some of the extracted ingredients have already been proven to have antioxidant and anti-inflammatory effects, which develop their positive effects even in small doses. But it doesn’t always have to be algae-based dietary supplements, because it is enough to mix a few seaweed strips (sea spaghetti) into regular pasta or salads or to enrich vegetable dishes, soups and sauces with a few algae flakes to achieve the desired effect. The possible applications for macroalgae are extremely diverse and are far from being exhausted in Europe. Although many people are now familiar with kombu used in miso soups and occasionally eat seaweed in a salad or mix it into smoothies, it is a far cry from healthy crisps made from dried algae, for example, which are very popular in Asia. Nevertheless, interest in algae is growing and the range on offer in stores is expanding. Organic seaweed-based seasonings are becoming more popular, breweries are producing algae beer from sugary seaweed (sweet kombu) and daring chefs are using dulse, red algae with a smoky aroma, as a bacon substitute.
The EU spends a lot of money on research
However, new ideas from researchers in algae reach much further. As part of the European project iCULTURE, which is funded by Horizon Europe with six million euros over a period of four years, 17 research partners from ten countries want to use macroalgae as a sustainable resource for the production of bioactive substances. To do this, they are developing special fermentation processes to convert the polysaccharides contained in seaweed, such as alginic acid, carrageenan or agar-agar, into bioactive ingredients, such as antimicrobial peptides. Some of these tiny protein building blocks are known to inhibit or even kill micro-organisms. This would perhaps give us the chance to use the peptides against pathogens, for example as a livestock feed additive or as an antibiotic alternative.
But food technologists and other scientists see even more opportunities to use algae more efficiently. For example, they could be used to produce polymeric bioplastics that are 100% biodegradable. As organic fertilizers, algae promote the growth of crops without polluting the soil. In addition, various biofuels such as bioethanol, biodiesel and biogas can be produced from algae. Given the health and ecological benefits of algae, it is easy to lose sight of the fact that they can also pose certain risks. For example, some types of algae have extremely high iodine contents between 5 and 11,000 mg/kg dry weight. Although there are no official recommendations or maximum daily iodine intake (RDI), it is generally accepted that the daily dose should not exceed 500 µg. Contamination with heavy metals such as lead and cadmium as well as exposure to inorganic arsenic or increased radioactivity can also be dangerous. That is why algae from known suspected areas must be checked particularly carefully before consumption.
Effective contribution to climate protection
The commercial cultivation of algae in aquaculture began only a few decades ago. Production varies depending on the type of algae, location and environmental conditions (light, nutrients), hydrodynamic situation (waves, tides, currents) and possible disturbances (diseases, herbivores). The net primary production per unit area of many macroalgal populations is among the highest of all habitats and can compete with that of tropical rainforests. Of the approximately 12,000 species of algae known to date, only a tiny fraction is used commercially. The FAO database for fisheries and aquaculture lists 47 species that are more or less regularly produced in aquaculture. Of these, only 12 species (mainly representatives of the genera Eucheuma, Laminaria, Undaria, Gracilaria, Pyropia and Porphyra) accounted for more than 95% of global algae production in terms of both volume and value in 2020.
Due to the many positive factors, it is obvious that interest in producing and commercially using algae is growing in other parts of the world outside of Asia. As part of its Green Deal, the EU Commission has launched an algae initiative to promote the development of a European algae industry. Algae cultures are intended to accelerate the transition to a green, circular and carbon-neutral EU. The stated goals are as ambitious as they are optimistic, because there are currently hardly more than 80 companies in the EU countries that are involved in seaweed aquaculture. However, the EU Commission estimates that member states could allocate half a million square kilometres of sea surface for seaweed cultivation, which is the equivalent of around 70 million football fields. If this actually succeeds, perhaps even part of the annual European imports of algae-based products worth almost 600 million euros could be replaced. However, the financial support for algae production is not only aimed at algae as a healthy superfood or meat substitute, cosmetic products, natural fertilizers or biofuels. Algae aquaculture is increasingly in demand precisely because of its ability to absorb CO2. They are able to bond up to three times more CO₂ than land plants. Cultivating them would help halve greenhouse gas emissions of the EU countries by 2030.
Improving the legal framework
Another advantage is that algae can be produced organically. However, the EU would not be the EU if the limits of what is permitted and prohibited were not defined by a meticulous set of bureaucratic rules. The EU Organic Regulation 2018/848 defines the site requirements, prescribes environmental assessments and requires algae producers to develop sustainability plans. Above all, it concerns a “balanced approach between economic use and the protection of biodiversity”. The EU report Blue Economy 2023 confirms that algae are a key to this new approach because they combine high benefits with low costs. Algae are a largely untapped resource with a limited carbon and environmental footprint. That is why the use of algae and algae-based products is being supported and financially subsidised as part of the EU algae initiative.
A lot of things still seem to be quite unstructured and inconsistent across Europe, with different laws and regulations applying in almost every member state. Even the list of algae species that could be produced in the future needs to be revised and standardized. For example, of the 700 species of algae found in Brittany, only 40 species are approved for human consumption. Experts estimate that around 150 species of algae are served and eaten on European coasts. However, only a fifth of these are officially approved as ‘novel food’ according to Regulation (EU) No. 2015/2283. A revision seems to be urgently needed here. The Brussels authorities have identified a total of 23 areas of action that need to be addressed in order to advance the development of the economic framework and the acceptance of algae and algae products in Europe.
Progress can be seen in some areas. The European Commission has funded over 100 research and innovation projects with around 220 million euros. However, macroalgae were underrepresented as most funding projects focused on microalgae. This is currently changing, as shown by the Nordic Seafarm initiative in Sweden, which emerged from a scientific research project. With EU funding, methods are being developed there for large-scale production of sea lettuce Ulva lactuca out at sea. This macroalga is also suitable for gastronomic purposes, as studied and tested in the EU initiative Phycogastronomy (derived from the ancient Greek term ‘phýkos’ for algae).
Preserving resources, increasing production
Algae represent an enormous bioresource that at present is hardly being utilized. Of the more than 100 megatonnes of algae that grow off the coasts of Europe every year (the largest biomass in Europe!), less than 0.25 per cent is currently utilized. In the future, this potential should be better exploited through sustainable, largely waste-free value chains in order to meet the ever-growing demand from the marine, animal feed, food and pharmaceutical industries. It is important to remember that the marine plants not only serve human commercial purposes, but also have an enormous impact on maritime ecosystems and biodiversity in the seas. It is for this reason the topic of protection of biodiversity and use of bioresources is also taken into account in the EU algae initiative. The EU-funded LINKFISH project (Investigating the link between sub-littoral algae habitats and fish communities in the Mediterranean Sea) investigated the structure of food webs in algal populations in shallow and deep water areas of the Mediterranean. The focus was on the importance of algae for fish production off Mallorca and Menorca at different times of the year.
Interest in algae is also growing in Europe. If aquaculture and the algae industry are to grow, we need a clear legal framework, fair competition rules and more administrative support for this still young industry. The conditions for this are very favourable, because unlike fish and shrimp farming, algae production is less complicated and much cheaper. Quick action is necessary because the sea is becoming increasingly crowded off the coast. Wind farms, shipping traffic, restricted military areas, fishing and tourism are making demands and taking up space. These are challenges that can only be solved politically.
Manfred Klinkhardt