Seaweed Farming for Food Security

To help solve hunger and malnutrition while also slowing climate change, some farmers could shift from land to sea, suggests a recent study from the Friedman School of Nutrition Science and Policy at Tufts University. The study was published in the journal Global Food Security.

Producing and selling seaweed could boost incomes for farmers in low- and middle-income countries (LMICs), particularly in coastal regions of Africa and Southeast Asia, said Patrick Webb, the Alexander McFarlane Professor of Nutrition at the Friedman School and senior author of the study. The other authors were Natalie Somers, N23, and Shakuntala Thilsted, who works for the Consultative Group on International Agriculture Research and won a 2021 World Food Prize for research and innovation in aquaculture and food systems. The team reviewed research papers, existing databases, United Nations and World Bank Group reports, and more.

A more sustainable alternative to raising livestock, seaweed cultivation requires no land, freshwater, or chemical fertilizers, and could become particularly profitable as demand for nutrient-rich seaweed products grows around the world, the study found. Those profits would mean more buying power for those households and communities who produce, process, package, and export the microalgae, which in turn would translate into healthier diets.

“One of the biggest problems of food insecurity in LMICs is the unaffordability of healthy diets,” said Webb, who also serves as director for the Food Systems for Nutrition Innovation Lab 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.”

Easy and environmentally friendly

A friendly crop for both farmers and the environment, seaweed has been grown in parts of Asia for centuries using fairly simple techniques, according to the study.

To start, farmers attach long lines of rope to the roots of the algae, which nourish the plant by absorbing nutrients from the water. Six to eight weeks later, they gather the seaweed by hand and dry it 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 said.

“Unless we get significant warming of the oceans, cultivating seaweed offers a way that is not just climate friendly, but climate proof,” said Webb.

On top of being relatively easy to grow, seaweed has a miniscule carbon footprint, and may even help lower the ocean’s carbon levels. Though little is yet known about how much CO2 seaweed releases during harvest, research has found that perennial brown algae farms absorb up to ten tons of CO2 per hectare of sea surface per year. In addition to its “carbon sinking” powers, when added to livestock feed, seaweed could help dramatically reduce methane gas 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.”

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