28 July 2021

How seaweed is changing the world

As climate change continues to exacerbate ecological challenges and considerably decreases the areas of agricultural land available, the global demand for nutrients will increase drastically. More and more, we will look to the oceans for our very survival.

Take seaweed, for example. For centuries humans have consumed seaweed in one form or another. Seaweeds are fast-growing algae with many beneficial uses to both marine life and humans. Through the process of photosynthesis, seaweeds convert sunlight into energy and take up nutrients and carbon dioxide from the oceans. While rain forests only produce 28 percent of the oxygen we breathe, seaweed, kelp, phytoplankton, and algae plankton produce 70% of the oxygen we breathe.

Would you believe that seaweed is actually the ancestor of everything that grows on planet earth? Paleontologists recently announced the discovery of a billion-year-old seaweed fossil in northern China. Some scientists firmly believe that all the trees and plants we have today originated from seaweeds.

With resources on our planet steadily decreasing, it’s no surprise then that humans have turned to seaweed for ongoing food and medicinal help.

Seaweed can be found in many everyday products. From cosmetics to medicine, pet food, and even toothpaste. Recently they’re also used in biodegradable packaging, textiles, and even straws.

seaweed

In 2019, the global seaweed business was estimated to be worth US$13.33 billion, with projections of that number reaching US$23.04 billion by 2027. Mostly farmed in Asia, inland seaweed farming outside of Asia has taken off in recent years.

Sustainable seaweed farming

The food industry’s interest in sustainable additives and food security grows each day, driven by a hungry population who are becoming increasingly concerned about the environment and the negative consequences of consumerism.

Seaweed farming began around 1670 in Japan and is now practiced all over the world.

While China, Indonesia, and the Philippines still produce most of the edible seaweed products on the market, seaweed farms are popping up all over the globe.

One such operation, AlgaPlus has a series of ponds and tanks in Northern Portugal where they cultivate seaweed in a much more controlled environment than that of traditional ocean seaweed farms. Their production includes the only European commercial-scale hatchery of the species Porphyra spp., also known as Atlantic nori.

Seawater from a coastal lagoon flows into the fish ponds at AlgaPlus, where it’s pumped through a filtration system into tanks that grow the seaweed. The advantage of this method of farming is additives or fertilizers are not needed, as the seaweed is nourished by the water from the fish in their ponds, making it a highly sustainable operation.

Seaweed
Seaweed on beach

In another part of the world, seaweed farming is proving to be a very important resource for women. Tanzania is an East African country and home to the Serengeti National Park. It might surprise you to know that seaweed farming is considered the third biggest contributor of foreign currency to the country, where 90 percent of seaweed farmers are women. In their shallow-water farms, they wait 45 days for their seaweeds to grow, then pick, dry, and package their seaweeds to be exported to countries like China, Korea, and Vietnam. But due to climate change, farmer numbers have dwindled over the past few decades.

At one point there were over 450 seaweed farmers in Tanzania. Now there are only about 150. But thanks to a program run by The Nature Conservancy, farmers are now being educated about how to improve their farming operations in the hopes of increasing the number of farmers in the region.

Common seaweed strains for consumption

While mainly consumed in Asian countries, seaweed products are starting to enjoy popularity around the world. Global seaweed aquaculture production now occupies about 20 percent of the total world marine aquaculture production by weight. Seaweed aquaculture production is dominated by relatively few species namely the brown kelps and the red seaweeds.

Different seaweeds / kelp

Pyropia is a genus of red alga found around the world in intertidal zones and shallow water and commonly used to make “nori” – a dried edible seaweed used in Japanese cuisine and often used to wrap rolls of sushi or onigiri. It has the highest commercial value per unit mass at $523 per wet metric ton. (In case you are wondering why nori is green but made from red alga, when added to boiling water (100 degrees C) the other pigments in the seaweed melt and dissolve leaving behind the bright green chlorophyll).

Kelps are large brown algae seaweeds that grow in underwater forests in shallow oceans. Along the Norwegian coast, these forests cover 5800 km2, and they support large numbers of marine animals. Kelp fetches $141 per wet ton.

Gracilaria (red algae) are found in warm waters throughout the world, though they also occur seasonally in temperate waters and cannot tolerate temperatures below 10 degrees C. Gracilaria fetches $273 per wet ton.

Kappaphycus is a genus of red algae with species distributed in the waters of East Africa, Malaysia, Indonesia, the Philippines, Micronesia, and Hainan Island. Kappaphycus fetches $172 per wet ton.

Sargassum is a genus of large brown seaweed that floats in island-like masses, never attaching to the seafloor. They can be found in shallow waters and coral reefs.  Sargassum fetches $460 per wet ton.

Read our blog: Why we need to tackle our sargassum issue

Consumed seaweed
Seaweed source of food
How seaweed farming can help combat climate change

Considered a carbon-negative crop, seaweed also has a high potential for climate change mitigation. Furthermore, seaweeds can grow extremely quickly, about thirty times faster than land-based plants. Indeed, nothing on earth sequesters carbon faster than giant kelp which can grow up to 60 meters in length and as fast as 50 cm per day under the right conditions.

The University of the South Pacific published an analysis as early as 2012 that revealed exactly how seaweed farming could help to combat climate change. Their analysis revealed that if 9% of the ocean were to be covered in seaweed farms, the farmed seaweed could produce 12 gigatonnes per year of bio digested methane. This methane could be burned as a substitute for natural gas. Even at smaller scales, seaweed farming has the potential to substantially lower atmospheric CO₂.

Seaweed in the food chain

Seaweed isn’t just eaten in sushi bars. Many of the foods we consume every day employ thickening agents to make them more palatable and easier to scoop. Several strains of red algae provide natural gels that bind food such as Agars, Alginates, and Carrageenans. Some of the products include desserts, chewing gum, jellies, jams, dairy products, salad dressings, candies, ice creams, jellies, beers, and wines.

Seaweed for the garden

Seaweed can also be applied whole to garden soil. You can also buy seaweed that is dried and ground for fertilizer.  Or you can buy seaweed that is processed and made into seaweed extract, which is then diluted for use. Seaweed fertilizer adds trace elements as well as plant nutrients like potassium, nitrogen, and phosphorus to the soil.

Furthermore, whole or dried seaweed also adds organic matter to the garden. Considering how toxic regular commercial fertilizers are for the delicate ocean ecosystems, seaweed fertilizers are a much safer option.

Seaweed for building houses

Probably the best use being given to seaweed in the Caribbean is in building houses. Sargassum bricks are made with the same technique as adobe bricks. The use of this seaweed can reduce the total cost of building homes by up to 50%, making it perfect for low-income families or sustainable buildings.

Seaweed for building houses
Other uses for seaweed

Uses for seaweed are virtually endless. They are used to make cardboard, paper, and even textiles. Seaweed is also used in pharmaceuticals as binders, stabilizers, emulsifiers, and for creating molds. Even the dental industry uses them in molding preparations. Hair strengthening treatments, as well as makeup, moisturizing creams and sunscreens are some of the products that are being produced with seaweed.

Read our blog: is your sunscreen harming the ocean?

Furthermore, methane emissions could be cut by 90 percent if livestock were fed on seaweed-based foodstuffs, rather than soy. It would also improve digestion whilst boosting the animals’ immune systems, thereby reducing the need for antibiotics.

Seaweed as a first choice

Not only does seaweed pose a solution to food scarcity and climate change, but it’s helping us to create biodegradable products. Next time you’re out shopping, reach for the products made from seaweed first. You’ll be doing the environment a ton of good

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