Off The Shelf #4: Under The Sea
Don't worry, I'm not about to break into song. This week, it's all about seaweed.
Think of farming and you probably conjure up an image of trundling tractors, the squawking and mooing of a motley crew of livestock, rolling fields of sun-dappled wheat… piles of manure. What you probably don't think about is that slimy green and brown stuff that brushes up against you when you’re larking about in the (freezing cold) sea.
And yet there’s actually a whole world of innovative ocean farming developing, and it hinges around seaweed. There are approximately 11,000 seaweed species around the world, more than 200 of which have commercial value. I was totally ignorant about this until recently, when I heard a brilliant episode of Radio 4’s ‘39 Ways To Save The Planet’. Farming seaweed surely can’t be one of them? I thought. But it is.
Here’s why: seaweed is a great food source in itself, and a perfect habitat for other food sources. But it’s also an excellent vehicle to sequester (capture and lock away) carbon. So it can help both feed, and heal, the planet.
Seaweed is farmed on ropes underwater, and once it starts growing, biodiversity flourishes. Nutritious kelp can grow by up to two feet per day, and in this environment, there can be an abundance of shellfish: mussels, scallops, oysters, clams. The density of life growing on and around these slimy ropes is intense, and this thriving ecosystem will then attracts all sorts of fish and other sea critters looking for shelter from predators among the vines. So there’s potential for a lot of food production from seaweed - it’s not just the seaweed itself (seaweed butter, anyone? Kelp noodles?), but the lifeforms that flourish from its presence. Who doesn’t love a moules frite now and then?
But here’s the real beauty. Seaweed is part of the puzzle for reducing carbon emissions. Firstly, there’s an ‘avoidance’ affect: the footprint associated with producing plants underwater is small compared to those on land, so eating kelp over kale can mean fewer emissions in the first place. But seaweed is also a carbon sucker. It grows extremely rapidly, producing oxygen as it does so and sucking in carbon dioxide from the sea (interesting fact: the sea absorbs a third of all man-made carbon emissions). This leads to the creation of seaweed biomass. This biomass can then be harvested for use (biofuels, for example), buried back in the ground where the carbon originally came from, or it might just sink away to the bottom of the ocean. In a nutclamshell, seaweed removes carbon from the atmosphere. And aside from being used for food, it can also be used for compost or as natural fertiliser, thereby helping to regenerate the land being used in traditional farming.
To those in the know, seaweed farming is an attractive proposition. As Bren Smith, an ocean farmer in Newfoundland, Canada, puts it: “why don’t you grow things that don’t swim away, and you don’t have to feed?” It’s also possible to farm seaweed without presiding over vast swathes of real estate, since it can be grown in columns on ropes - essentially a 3D farming system. Smith can grow almost 4 metric tons of the stuff per acre (that’s the weight of three Ford Focuses), and a quarter of a million shellfish per acre (that’s more than the cast of Finding Nemo). On top of this, technology is being developed to accelerate production. Essentially, as Adrian Macleod from the pioneering Scottish Association for Marine Science explains, there is a technique which involves taking the reproductive part of familiar seaweed species, cleaning it up in a lab, and having an automated system of spraying this reproductive matter onto ropes (too much information?) This is key to scaling up production – which supports the case for huge growth potential in this 15 billion dollar industry.
There we have it. Save the planet by eating seaweed and growing it everywhere. Nutritious food for all and net carbon negative way before 2050 once we get these farms popping up everywhere.
Well, it’s not quite that simple. It’s not clear how much of a dent seaweed farms could make in the global fight against climate change. According to Tamsin Edwards of Kings College London, natural seaweeds already fix about 7% of human CO2 emissions, which is great. But even if this industry’s current growth rate (8%) was to double, it would likely only offset a further 0.1% of emissions. But there are larger-scale estimates. If we can cover 2% of the area of the world’s ocean with seaweed farms (an area the size of Australia), that could potentially offset 15% of man-made emissions. 15% seems too good to be true, but even if the industry grows to a point where it can offset just a few more percentage points, surely every little helps. And Tesco might get an exotic new line of vegetables.
It’s encouraging to see a nascent, thriving seaweed farming industry developing across the globe, and the UK is no exception. The West Coast of Scotland is a prime location for seaweed farming, with the establishment of the Seaweed Academy, which recently received 400k in funding from the UK government. This is the UK’s first seaweed industry facility, aimed at supporting expansion and skills development for the seaweed aquaculture industry. It’s not just the north. the Devon Environment Foundation, along with regenerative business Vivobarefoot and the Universities of Plymouth and Exeter, recently awarded a grant to innovators Biome Algae to establish themselves on the south west coast, with the intent to produce more than 250 tonnes of seaweed per year from 4 sites. This is an exciting space to watch.
So I’ll end with the big question: is seaweed worth eating? Well for a start, it’s nutritious. Packed with fibre, protein, vitamins and minerals, it definitely has a place in a balanced diet. Just beware, because not all seaweeds are good for you – some are in fact toxic, such as those found in freshwater lakes. Stick to the sea.
Is it nice to eat? Well, it’s got a whole section on greatbritishchefs.com, so there must be some potential. But my frame of reference here – to my shame – is the seaweed you get sprinkled on prawn toast and spring rolls from the Chinese takeaway. Which is lovely. But this week, my life changed for the worse. I learned that this isn’t seaweed at all: it’s actually dried and fried cabbage. I’ll never quite be the same again.
So this leaves me with a mission: get out there, find some real seaweed and make a meal with it. I’ll get back to you with my verdict.
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