From sustainable food to biofuel, there’s more to this underrated plant than you might think – and it can help improve the health of our seas as it grows.
If seaweed to you is just something that gets tangled around your ankles when you take a dip in the sea, it’s time for a rethink: it could play a key role in helping us lead more environmentally sustainable lives. Here are four things you probably didn’t know about seaweed.
1. It’s good for us and the planet
We all know that eating a more plant-based diet is one way to tackle climate change, but eating a wider range of plants instead of relying on an intensively farmed handful is also a more eco-friendly choice – and seaweed could be one of them. When you think about seaweed-based foods, you might think of nori, which is used to wrap sushi rolls, or the laver used in laverbread, a traditional part of Welsh cuisine. However, seaweed could play a wider role in feeding the growing global population.
Seaweeds such as laver and wakame have been identified by WWF as ‘future foods’ – crops with a high nutritional content (seaweed contains vitamins A, C and E, as well as iodine and antioxidants) which can be farmed with relatively low environmental impact.
‘The chances are, you’ve already eaten seaweed, as it’s used to make the setting agent agar-agar, which is used widely in a range of processed foods,’ says Good Housekeeping cookery editor Emma Franklin. ‘If you want to cook with seaweed, try topping poke bowls or salads with shredded sheets of nori, simmer dried kombu in broths and soups for a lovely umami flavour boost, or toss strips of rehydrated wakame in dressing and serve as a vegetable side dish.’
It’s worth noting, though, that because it’s so rich in iodine, the British Dietetic Association recommends eating seaweed no more than once a week.
2. It can be farmed in an eco-friendly way
‘You don’t need any pesticides, fertiliser or fresh water to grow seaweed. We just plant it and it does its thing – so it’s true zero-input farming,’ explains Ella Sturley from Câr-y-Môr, a three-hectare community-owned seaweed and shellfish farm located off the Pembrokeshire coast.
Some types of seaweed grow incredibly quickly, which means they can regularly be harvested when farmed, a bit like ‘cut-and-come-again’ lettuce. The rope-grown sugar kelp grown at Câr-y-Môr, amongst which other species self-seed, grows up to 1m per month. ‘We don’t strip the line completely when we harvest the seaweed – we only take off around three quarters of the length – so there’s always some seaweed there to support the marine life that’s grown up around it. Then it simply grows back,’ Ella explains. The Câr-y-Môr seaweed is farmed alongside mussels, scallops and oysters to make the area that is cultivated more productive.
3. Seaweed boosts sea health
‘Ecologically, seaweeds are vital as they are at the heart of our marine ecosystems,’ says Professor Juliet Brodie, Merit Researcher, Phycology, at the Natural History Museum. ‘Seaweed can help restore marine ecosystems and well-managed seaweed farms could play a part in that by attracting fish and other marine life,’
As with anything, there needs to be a balance, she adds. ‘I hope that we can learn from what’s happened with land-based farming. Seaweed aquaculture can have many benefits and can provide a reliable crop in the long term but at the same time there could be unforeseen ecological risks associated with monocultural seaweed farming on a very large scale.’
As well as supporting biodiversity along our coasts, seaweed also plays a role in removing pollution from the surrounding sea and helps regulate sea acidity, which increases when carbon dioxide builds up in the atmosphere and is absorbed by our oceans.
However, while seaweed absorbs carbon as it grows, more research is needed to determine exactly how much of this carbon can be stored away beyond the life of the plant in a way that helps to tackle climate change.
4. It can be used for more than just food
Most of the seaweed that is harvested today is consumed as food or used in animal feed, but experts are currently exploring other uses in biofuels, bioplastics, as seaweed-based fertilizers and even as food supplements for cattle to reduce the amount of methane they produce.
‘One of the main ways that seaweed reduces carbon is by replacing some products that are more carbon intensive,’ explains Piers Hart, WWF Seafood and Aquaculture Specialist. ‘One of the big ones is fertiliser. The synthetic fertiliser used on farms is very carbon intensive to produce but there’s research happening now to see if we could use seaweed fertilisers to replace some of that. If this is possible, we’d have a much more circular system because the seaweed growing on seaweed farms would absorb some of the nutrients from fertilisers that run off farmland and end up in our seas, and actually return these nutrients to farmland when seaweed-based fertiliser is used on it.’
It could even help secure the future of our coastlines, Piers adds. ‘There’s talk now about whether seaweed farms also have the potential to reduce coastal erosion and protect our coastline and the communities that live close to it. It’s thought that seaweed farms that are close to shore could help reduce wave action.’