What You Don’t Know About Seaweed—But Probably Should

©istockphoto/richcarey

We walk into the classroom with hesitant uncertainty. Jennifer Hahn, sea kayak guide and “natural food expert” is standing underneath a giant chef’s hat, behind three 2-burner camp stoves. “Here, try this,” she says mid-stir, handing each of us a sampler cup of a green-tinged seaweed chowder. It’s delicious. She feeds us soup, pudding, pickles, and salad all made from…seaweed. It’s part of a class on harvesting and cooking foods from kelp.

Seaweed may be the world’s most underrated plant. The fact that we call it a “weed” shows how little respect the families of green, brown, and red algae get from humans. But seaweed is great stuff. You can eat it, it’s a vital nursery for fish, and some of the cutest creatures on the planet can’t live without it. Next time you see some funky green stuff on the beach, show some respect.

It’s Not A Weed, It’s A Forest
Seaweed is more than a weed; in fact, think of seaweeds as the plants in an underwater forest. Anyone who’s SCUBA dove in a kelp bed (or peered through the glass of the Monterey Bay Aquarium) knows that it packs a lot of vertical complexity. The stalks of big seaweeds (bull kelp, giant kelp, winged kelp, and lamanaira) look like the trunks of trees, behaving in the same way: reaching skyward toward the light and providing a sheltering place for creatures of all kinds. Seaweed is more than a plant: it’s an entire ecological structure in coastal zones. Even the “small” kelps that grow in intertidal rocks, like sea palms and sea lettuce creates a micro-ecosystem, providing shelter from the pounding waves, matts of vegetation to hide from predators and plenty to eat. Seaweed, along with plankton, is the basis of the food chain close to shore.

No Kelp, No Sea Otters
And without kelp, there are no sea otters. Sea otters are adorable. But they’re also more than cute: they’re the furry floating linchpins on which the Pacific Coast ecosystem rides. Sea urchins eat kelp at a massive rate if left undisturbed. And sea otters eat urchins at an equally massive rate, keeping the population in check. Where otters are absent after having been hunted for their fur, urchins graze entire sea bottoms to an “urchin barrens.”

And the otters also need the kelp: it gives them protection from the waves and places to hide from sharks and orca. Where sea otters have been reintroduced where some kelp still remained, like the coast of Vancouver Island, they’ve thrived and kelp forests have regenerated. Where the kelp had all been munched to nothing by urchins, like Oregon’s coasts, the reintroduced otters didn’t make it.

No Seaweed = No fish = Hungry Humans
And without seaweed-based ecosystems, we’d have far fewer fish. Second only to coral reefs in terms of fish production, seaweed is a massive contributor of marine ecosystems. Sixty-eight percent of the carbon in a greenling (a fish-eating rockfish) ultimately comes from seaweed. And without fish, we’re in trouble. Sixteen percent of all human protein comes from fish caught at sea, and 95 percent of that comes from nearshore waters where seaweed is often the main ecosystem driver. Unlike protein from cows, chicken, pigs, or even soybeans, fish protein is mostly wild-caught (only 15 percent comes from aquaculture) which means that if we take good care of the oceans and don’t overfish, it can be a source of sustenance for a long time.

It’s Good For You
Seaweed is good for you—so good for you, in fact, that Simon Fraser University professor Louis Druehl calls it “sea vegetables.” It’s most famously used in nori, the wide rolls for dried seaweed familiar to sushi eaters, which comes from the kelp Porphyra. Nori packs twice to three times the amount of vitamins B1, B2, Niacin, B6 and B12 as spinach, and other seaweeds like sea lettuce and kombu aren’t far behind. And it’s easy to harvest and cook with, as our classroom session proved.

We Make Stuff Out of It
Seaweed also appears in a variety of everyday products. It’s an element in lotions, creams and shampoos. The plant gums in seaweed are used to maintain the texture of toothpaste and the shape of dental molds. Pharmaceutical researchers are exploring the value of seaweed extracts in tumor treatment and blood pressure management.

Seaweed May Slow Global Warming
A recent study by Deakin University in Australia reveals that seaweed also may play a big role in fighting climate change. It’s a fast-growing plant, which means that it pulls a lot of carbon dioxide out of the atmosphere through photosynthesis to fuel its growth. Until recently, it was assumed that because seaweed breaks down quickly after it dies, this CO2 isn’t stored for long. But this may not be true after all: the Deakin study indicates that some seaweeds may be storing carbon for quite some time due to the structure of their cell walls.

So next time you walk on the beach and complain about the mess of washed up seaweed, have some respect. Seaweed is good stuff, it’s good for you, and it’s good for the sea.