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Seaweed farming could boost food security, slow climate change

A new study led by Tufts University has found that seaweed farming could help mitigate hunger and malnutrition while also slowing climate change. Furthermore, the experts report that producing and selling seaweed could boost incomes for farmers in low- and middle-income countries, particularly across coastal regions in Africa and Southeast Asia.

Since seaweed farming requires no land, freshwater, or chemical fertilizers, it is a much more sustainable alternative for raising livestock and could become highly profitable as demands for nutrient-rich seaweed products grows around the globe. Such profits would increase the buying power for the households and communities who produce, process, package, and export it, which in turn could lead to healthier diets worldwide.

“One of the biggest problems of food insecurity in LMICs is the unaffordability of healthy diets,” said study lead author Patrick Webb, a professor of Nutrition Science at Tufts. “There are roughly 3.5 billion people in the world who can’t afford a healthy diet even if they choose local foods at local prices. For many of those people, cultivating and selling seaweed would lead to higher incomes and improved nutrition through purchases on the market.”

Simple techniques 

Historically, seaweed has been grown in parts of Asia for centuries, using simple techniques. For instance, farmers attach long lines of rope to the roots of the algae, which help nourish the plant by absorbing nutrients from the water. About two months later, they gather the seaweed by hand and let it dry in the sun.

“A lot of what we’re looking at on the farming side is not about finding new crops or different kinds of crops. It’s about what’s already being grown that could be scaled up cost-effectively,” Webb explained.

Low carbon footprint 

Besides being relatively easy to grow, seaweed has a very low carbon footprint, and could even help decrease the ocean’s carbon levels. Although little is yet known about how much carbon dioxide seaweed releases during harvest, perennial brown algae farms were found to absorb up to ten tons of CO2 per hectare of sea surface each year. Moreover, when added to livestock feed, seaweed could help substantially reduce methane emissions.

“Unless we get significant warming of the oceans, cultivating seaweed offers a way that is not just climate friendly, but climate proof,” said Webb. “We don’t know how soon the industry will start to experience the negative effects of climate change, but the potential looks good. By farming seaweed, it’s not going to accelerate those negative effects. Whereas cutting down trees and adding more livestock certainly would.”

Challenges of seaweed farming 

Unfortunately, there are several challenges for producing and processing seaweed. Since ocean waters are becoming increasingly acidic due to climate change, growing healthy, edible seaweed in such conditions is not easy. Moreover, seaweed’s main value as an export lies in some of its extracts as ingredients for other products, rather than as a vegetable to be eaten whole, and many LMICs    do not yet have a proper infrastructure to effectively process, test, and regulate what will eventually land on consumers’ plates.

“The steps taken between the farm and the fork, that’s what we need to focus on,” Webb argued. “We need to work more closely with governments and the private sector to figure out where the bottlenecks are and how to overcome them.”

Unlimited opportunities 

However, if these obstacles are successfully addressed, the opportunities of seaweed farming are boundless. The industry has already flourished in countries such as Indonesia, where seasonal labor is always available and farms have managed to achieve industrial-level economies of scale. The country is now a key exporter of two seaweed species from which carrageenan – a thickener found in meats and nut milks – is extracted.

“There are many different types of seaweed, and they all require somewhat of a different environment in which to grow. The vast coasts of Africa and Asia, not all of it will be prime real estate. But much of it will be,” Webb said.

In order for seaweed farming to expand and flourish in these regions, government should create food safety regulations and help attract local and international investment. “The Ministry of Agriculture, or even the Ministry of Fisheries in these countries probably never discusses seaweed. What if they did? They might discover a goldmine,” Webb concluded. The study is published in the journal Global Food Security.

More about seaweed farming 

Seaweed farming is the practice of cultivating and harvesting seaweed. In many parts of the world, it’s a significant industry that can be a vital source of income and food.

Cultivating seaweed

There are various methods for cultivating seaweed, depending on the species and environmental conditions. Most methods involve using a substrate like ropes or nets, which the seaweed can attach to and grow from. The substrate is then anchored to the seabed using weights or floats to maintain its position in the water. For some species, such as kelp, farmers use horizontal long-lines near the water’s surface, to which juvenile kelp is attached. The seaweed then grows hanging downwards.

Harvesting seaweed

Once the seaweed has grown sufficiently, it is harvested. The method of harvest again depends on the type of seaweed and its growth. Some seaweeds can be harvested by hand or using simple tools, while others may require more complex machinery. After the seaweed is harvested, it can be dried, processed, or sold fresh, depending on the market.

Applications of seaweed

Seaweed has a wide variety of uses, including food, fertilizer, and various industrial uses. It’s a popular food item in many Asian countries, particularly in Japan, Korea, and China, where it’s used in soups, salads, snacks, and sushi. Seaweed is also a source of carrageenan and agar, which are used as thickening and gelling agents in the food industry. Seaweed is also being researched for its potential uses in biofuel production, carbon sequestration, and as a source of valuable compounds for pharmaceutical and nutraceutical industries.


Seaweed farming is considered a sustainable practice as it doesn’t require fresh water, arable land, or fertilizers, which are resources commonly used in traditional agriculture. It can also help improve water quality by absorbing excess nutrients, and some types of seaweed can even absorb carbon dioxide, helping mitigate climate change.


By Andrei Ionescu, Staff Writer

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