10 Things You Didn't Know About Seaweed

We chat with Susan Hand Shetterly, who offers a look into the extraordinary life cycle of seaweed, teaching people about its role in local environments and its interconnected global significance.

Kara Rota
3-minute read
Episode #210

Seaweed. You may not realize it, but it’s almost impossible to go through a day without encountering it, whether it's on your favorite sushi roll, hiding in your cosmetics, or incorporated into your vitamin supplement.

And beyond that, seaweed is utterly essential to our world. It produces much of the oxygen we breathe, forms the basis of all marine life, and serves as the linchpin for coastal communities across the globe. Nature writer Susan Hand Shetterly plumbs the depths of the most overlooked yet ubiquitous species on earth in Seaweed Chronicles: A World at the Water’s Edge. 

Here are ten things you probably didn't know about seaweed.

1. Seaweeds are not plants. Seaweeds are algae—similar to the one-celled phytoplankton most people associate with the term. More specifically, seaweeds are macroalgae, meaning “big algae.” They are made up of single alga cells that are bonded together into one structure.

2. Phycologists—scientists who specialize in seaweeds—estimate there are between 30,000 and 1,000,000 species of seaweed worldwide. This means there is much more to discover about seaweeds, and probably many more things we can learn to make from them.

3. Seaweed is the future of fishing and farming. Industrial fishing has depleted many fish species across the globe. Meanwhile, rising populations of people and limited space for farmland signal a potential food crisis. But farming seaweed responsibly brings in large amounts of a healthy new food source and creates jobs. It also doesn’t require fresh water or fertilizer, making it one of the most sustainable crops on the planet.

4. Seaweeds growing in clean, aerated waters are rich in protein, fiber, vitamins and minerals, and amino acids. The Japanese eat more sea-weed than anyone else in the world, and some nutritionists attribute regular consumption of seaweed to the country’s high life expectancy.

5. The value of harvested seaweeds stands at about 6 billion dollars a year. Food for humans makes up about 5 billion dollars, and extractions for other purposes—including medicine, cosmetics, research materials, fertilizers, and much more—make up the rest.

6. Seaweed can help protect the environment in the face of climate change. Roughly 25% of the CO2 in the atmosphere is absorbed into oceans, where it causes increased acidity. Worldwide, ocean surface waters have become 30% more acidic over the last 150 years, as reported by the U.S. government’s 2017 climate science special report. Seaweeds—much like plants on land—absorb that CO2 as a nutrient needed to help in photosynthesis, filtering it out of the water.

7. At least 35 countries are involved in seaweed production, either in cutting wild seaweeds or starting their own aquaculture projects. China and Indonesia are the largest producers of aquaculturally grown seaweeds in the world. The United States and Europe are quickly catching up.

8. Maine is fast becoming the largest resource for edible and commercial seaweeds in the United States.

9. Two major events of 2011 changed the scope of today’s global seaweed industry. The Fukushima nuclear disaster prompted fears of contamination in Pacific seaweed, and Hurricane Irene washed away a year’s harvest of wild Atlantic seaweeds. To keep up with increasing demand, some wild harvesters in the North Atlantic turned to farming.

10. Seaweed may be the next biofuel to power our cars, planes, and trains, or even used to make electricity. The U.S. Department of Energy recently awarded a $1.3 million research grant to the University of New England “to develop the tools to enable the United States to become a leading producer of macroalgae,” with a focus on developing transportation fuels.\

Excerpted with permission and adapted from Seaweed Chronicles: A World at the Water’s Edge, by Susan Hand Shetterly, Algonquin Books, August 2018

About the Author

Kara Rota

Kara Rota headed children’s programming at Chicago’s Green City Market and studied food politics at Sarah Lawrence College. Kara has been a featured speaker at numerous venues including Food Book Fair, the Roger Smith Food Conference, and the Brooklyn Food Conference. She has written about food for Irish America Magazine, West Side Rag, Recipe Relay, and Food + Tech Connect, and is the former Director of Editorial & Partnerships at Cookstr.com.