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I am sure many of us have walked along a beach after a storm and witnessed seaweed strewn amongst the sand. Many of us would consider it to just be a foul-smelling “weed” without realising that most of us consume seaweed every day in food products such as sushi or miso soup, or seaweed extracts in foods such as ice cream, and yogurt. Humans have eaten seaweeds for tens of thousands of years and today the diets of billions of people, especially in Asia, are based on cultivated seaweeds. The Japanese culture, in particular, has long known that seaweeds are a superfood. “Research has linked the Japanese diet – high in fish, seaweed, soy, fruits, and vegetables to lower rates of cardiovascular disease, Type 2 diabetes, obesity and cancer in general.”

But there is more to seaweed than just the superfood story. The value of seaweed is such that it could help the planet combat food insecurity, mitigate climate change, clean and repair our oceans and create economic transformation and sustainability for countries that embrace this amazing sea vegetable.

“If you cover 9% of the world’s oceans in seaweed farms, you could draw down the equivalent of all our current emissions — more than 40 gigatons a year.” – Tim Flannery

Seaweeds are a group of algae, found in seawater, and come in green, red and brown species. Over 90 percent of commercialized seaweed today is marine farmed mostly in Asia. Green and red species do not need a holdfast, (or something to grow on), so can be farmed onshore if desired in salt water concrete ponds, tanks or bioreactors. Brown species need a holdfast and are farmed on ropes or other structures (the holdfast attaches to the rope) in the ocean.

Seaweeds are the world’s fastest growing plant – growing 30-60 times faster than land-based plants and soaking up to 5 times more CO2. New Zealand Bladder kelp (called Giant Kelp in most parts of the world) can grow as much as 60 cm (two feet a day) and up to 45 meters 150 feet in length.

Conventional agriculture has taken a big toll on the environment. It is estimated that by 2050, the earth will be home to as many as 10 billion people up from 7.5 billion today. Moreover, according to the United Nations at current rates of soil loss, we have just 60 years of harvests left.  If massive increases in agricultural yield are not achieved, matched by a corresponding decrease in the consumption of water and fossil fuel, a billion or more people could face starvation. Hunger could be the 21st century’s most urgent problem.

Unlike other plants, seaweed does not require soil, fertilizer, fresh water, or pesticides to grow but actually improves the environment in which they flourish. Farmed brown seaweed fixes nitrogen, so harvesting it can clear areas of water polluted by nitrogen fertilizers from urban or agricultural runoff.

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Even in a very basic example, a past generation of farmers in Cornwall, England interested in improving poor soil quality loaded seaweed onto carts drawn by horses and mixed it with sand and haulm (stems, stocks of plants) and placed it on their farms. They are estimated to have added up to 3-4 feet of high-quality soil using this process. 

An ocean afforestation report by Antoine de Ramon N’Yeurt and a team of scientists at the University of the South Pacific shows that if seaweed covered 9 percent of the ocean it could produce enough biomethane to replace much of today’s demand for fossil fuel energy while also removing 40-53 gigatonnes of CO2 (a big part of all current human emissions) per year from the atmosphere. It would also create a nurturing environment for sea life increasing sustainable fish production to provide 200 kg per year, per person, for 10 billion people.

The worldwide commercial seaweed market is estimated to grow from US$10.6 billion in 2016 to between $26 billion by 2025 and more bullishly to US$87 billion in 2024.

Currently, seaweed has been developed for a myriad of sectors including food, food additives, soil bio-stimulant fertilizer, industry gels, pharmaceuticals, textiles, cosmetics, and paper products.

What are some of the new opportunities driving this growth?

  • Cows release a significant amount of methane into the atmosphere, a gas that is approximately 25 times worse than carbon dioxide. A scientific discovery by James Cook University in Queensland has shown that a species of dried seaweed used as an additive in cattle feed may reduce methane emissions by 50-70 percent or more, however, more research needs to be done to prove commercial viability.   
  • It is estimated that our demand for plastics will double in the next 20 years. Most plastic is currently manufactured from petroleum but new biodegradable plastics from Polylactic Acid (PLA) are being sourced from plants such as corn and sugarcane. Seaweeds and algae are being trialed to make certain bioplastics with the benefit that unlike corn or sugar cane,  they do not compete directly or indirectly for land for food, feed or fiber production and with some brown seaweeds producing over 15 times more biomass per hectare, compared to 8-15 tonnes per Ha for corn and over 200 tonnes for seaweed.
  • A start-up Algiknit is using seaweed to create yarns for textile production that are durable yet biodegradable when no longer needed. Maybe the Allbird shoe story will evolve even more with a next-generation shoe blending seaweed and merino wool.
  • Many countries including the USA and the UK are investing significant funds to research the opportunity to use seaweed and algae sources as a biofuel to replace fossil fuels.

According to National Geographic around a third or more of all man-made carbon dioxide ends up in the oceans. In less than 100 years, there has been a 30 percent increase in ocean acidity.

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As the ocean becomes more acidic it decreases its ability to absorb and moderate climate change while increased acidification reduces the amount of carbonate, a key building block in seawater. This makes it more difficult for marine organisms, such as coral and plankton to form their shells. The concern is that ocean acidification will slow the growth rate of cultured oysters, mussels, and other shellfish to a point where they are not going to be sustainable or profitable in the future.

“In the waters of the Yellow Sea off North Eastern – China, seaweed farms occupy 500 square km of the ocean surface yielding around 400,000 tonnes of seaweed annually. The seaweed takes in the CO2 and through photosynthesis removes the acidifying CO2”.

An acidic ocean impacts calcification and makes shells “less hard”. The Smithsonian predicts that mussel and oyster shells will be 25 percent and 10 percent less hard respectively by the end of the century thus increasing the chance of them fracturing during processing/transportation as well as being crushed or eaten by other sea creatures. A recent study has shown that Sydney Rock Oyster farmers are producing fewer amounts of plate grade oysters and more smaller less marketable oysters which may be linked to the change in ocean acidity.

By 2100, the global annual loss for molluscs from ocean acidification

alone could be over US$100 billion.

The good news is that research in Maine has shown that when seaweed is co-located on mussel farms a “halo” effect occurs with a significant reduction in acidification in and around the marine farm. It also makes the water more hospitable to shellfish earlier in the spring season with the end result of a heartier crop, and a shorter time until shellfish reach market size while adding another source of income for farmers.

New Zealand has a small but growing seaweed industry based currently upon a wild harvest. With a large coast, numerous harbours and clean great temperate ocean blue waters, farmed seaweeds and a supportive government policy could be an incredible blue-green growth story for the country.

Let’s imagine a day where there are hundreds of ocean farms around NZ contributing food, bio-fertilizers, nutraceuticals,  energy and much more to local economies while saving our ocean, the climate and ourselves.

Yet while more than 70 percent of earth’s surface is dominated by oceans, we currently only produce a paltry two percent of the globe’s food, feed, and biomaterials from this source.

We are yet to begin to harness the ocean’s potential.

Follow Pure Advantage for Tom McLeod’s next article on how New Zealand can capitalise on seaweed and create a new platform for high-value economic growth and sustainability.

Featured images from Troy Williams and Andrew Buchanan  at Unsplash.

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