Seaweed Saviour: How improvements in seaweed farming can provide solutions to global food security and climate change.

Reference: Kristoffer Stedt, João P. Trigo, Sophie Steinhagen, Göran M. Nylund, Bita Forghani, Henrik Pavia, Ingrid Undeland. Cultivation of seaweeds in food production process waters: Evaluation of growth and crude protein content. Algal Research, 2022; 63: 102647 DOI: 10.1016/j.algal.2022.102647

In the face of wavering global food security and rapidly intensifying climate change, seaweed farms may provide an alternative source of nutritious and protein-rich food. A new study has found that waste water from other food production processes can improve the growth of seaweed, making seaweed a more viable solution the world’s growing food security issue.

One farms trash is another farms treasure

A group of researchers from Sweden tested the growth rate and protein production of seaweed in the waste water from different food production processes. They found that green seaweeds, which are often used in east-Asian cuisine, showed significant increases in growth rate and protein production when cultivated in waste water from other food production processes.


Seaweed farm in Tanzania. Image source: Matt keiffer

The increase in growth rate and protein production varied between the different species and was affected by the varying levels of nutrients in each of the process waters. In the most impressive cases, the growth rate of seaweed was up to 64% higher in the processed water than in the control and the protein content of the seaweed was almost four-times as high. These results show that cultivating seaweed in waste water could significantly increase the output of seaweed farms.

Scrumptious Seaweed

By growing seaweed in food production waste water, the researchers were able to increase the protein content of seaweed to 30%, rivalling that of soya beans which are another popular non-meat source of protein. Seaweed also contains many other important vitamins and minerals and is one of the best natural sources of iodine, a substance which is vital to the hormone-regulating thyroid gland.

Seaweed salad from the Philippines. Image source: Obsidian Soul

Thanks to its high nutritious value, seaweed has been eaten in Asian countries like Japan and China for centuries. Even Britain has a history of seaweed farming, particularly in Gaelic communities like Scotland and Ireland where Dulse, an edible seaweed, has long been harvested as a source of food. Nowadays, edible seaweeds, like Dulse, are being recognised for the potential to provide a cheap and nutritious source of protein for communities all over the world.

Sustainable Seaweed

Seaweed farming may not only help to provide a solution to global food security, but it can also play a role in mitigating the effects of climate change. Seaweed is natural carbon sink, which means that as it grows, it absorbs carbon dioxide from the air, removing it from the atmosphere and storing it in their bodies. This means that seaweed farms often produce negligible amounts of greenhouse gases, making them one of the most sustainable types of food production.

Seaweed can also reduce the greenhouse gas emissions from other industries. For example, supplementing the diet of cattle with seaweed has been shown to reduce their methane emissions by more than 80%. Seaweed provides a more sustainable alternative to other crops that are used to feed livestock which are often grown in giant mono-cultures on land, which reduce biodiversity.

Supplementing a cow’s diet with seaweed can reduce their methane emission by over 80%. Image source: USDA

Waste not, want not

The findings of this study, and of others like it, point to a way in which seaweed farming can become even more sustainable. By using waste water from other food production processes, seaweed farms can prevent that waste from ending up in rivers, lakes and coastal regions where it can have devastating consequences. Nutrient run-off from agriculture and other types of farming can cause the formation of massive dead zones in coastal areas where no life can survive.

Re-cycling waste water in this way can also provide a financial benefit to the companies who produce it, as disposing of it safely can be an expensive process. Finding ways for companies to re-use and re-cycle their waste products will help industries move to more sustainable circular economies. Using waste water to improve the output of seaweed farms is a great example of how implementing circular-economy-based practices can help industries to save costs and become more sustainable.

Cover photo by Janne Hellsten

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