The leaves resemble brown lasagna noodles when they wash ashore on coasts around the world. Like many other seaweeds, sugar kelp has all sorts of uses. The leaves of Saccharina latissima provide a sweetener, mannitol, as well as thickening and gelling agents that are added to food, textiles and cosmetics.
But some believe its most important potential is largely untapped: as an addition to the American diet.
Seaweed is widely cultivated and consumed in Asia. However, in North America, where it sometimes is rebranded as a "sea vegetable," it is cultivated rarely and eaten infrequently. To proponents, this is the unfortunate oversight, considering it is a crop that can clean the water in which it grows, needs no arable land, and provide a nutritious food with traditional roots.
There is, of course, a matter of perception.
"You have to remember in Western countries, people say 'seaweed,' what do they think of? The glop that's on the beach. They don't realize there are resources sitting right in front of them," said Charles Yarish, a biologist at the University of Connecticut.
Yarish, a seaweed expert, is collaborating with a Maine company that sells seaweed cut as noodles, salads and slaw. He hopes to plant the seeds of an industry off the coast of New England, starting with the long brown fronds of sugar kelp.
Big business elsewhere
As a source of food for humans, the oceans have reached a tipping point, according to a 2006 report from the U.N.'s Food and Agriculture Organization. Fishermen have harvested the ocean essentially like hunter-gatherers for millennia, but traditional fisheries no longer can produce enough fish to keep up with the rising demand for seafood.
Meanwhile, aquaculture has increased and may have the potential to dramatically increase food production, in what has been called the Blue Revolution.
Seaweed is a part of this revolution. The cultivation and harvest of plants made up almost a quarter of the quantity of global aquaculture's output in 2004, according to the Food and Agriculture Organization. Increasingly, seaweeds and shellfish are being grown alongside fish or shrimp pens, where they can feed off the excess nutrients, becoming part of a system that produces an additional crop instead of a pollution problem.
Most seaweed, both harvested and cultivated, is eaten, according to a 2003 FAO report. For more than a millennium, it has been part of the diet in China and Japan, which are among the largest consumers and producers of seaweed. In the last 50 years, global hunger for seaweed has grown beyond what wild plants could provide, and now cultivation meets 90 percent of this demand, according to the FAO.
Americans were introduced to seaweed as food when sushi began gaining popularity in the 1970s, and consumption has been growing ever since, said David Myslabodski, sole proprietor of Great SeaVegetables, a consulting business in Maine.
Although North Americans are eating more seaweed, most of it is imported. Seaweed farming is "almost painfully nonexistent. There are very few cases, very small-scale," Myslabodski said. "You always see people trying and trying, but it is probably less successful than opening a restaurant.
Promoting seaweed as a source of nutrition – added to livestock feed, in fertilizer, or as human food – is more than a job to Myslabodski. "I am going to do whatever I can, until I kick the bucket, to have sea vegetables on the plate," he said.
Success stories do exist. Near New Brunswick, Canada, Cooke Aquaculture raises seaweed and mussels alongside its salmon pens to suck up the excess nutrients produced by the fish. The seaweed goes to local restaurants and a spa.
In Hawaii, the native tradition of eating seaweed, called limu, has melded with the diets of Asian immigrants. Together, edible seaweed and tiny algae, grown as feed additives and nutritional supplements, are Hawaii's most valuable aquaculture crops, according to the state government.
The United States needs to catch up with Asia's seaweed production, said Kevin Fitzsimmons, a professor at the University of Arizona and a former president of the World Aquaculture Society.
It provides a balance to a lot of the damage we are doing to our environment in that it's taking wastes we put in the ocean and converting those into a good product," Fitzsimmons said. Seaweeds use carbon dioxide, nitrogen, phosphates, some heavy metals and a lot of micronutrients. They also provide a base for other organisms, like sponges, bacteria and barnacles, which break down organic compounds and other pollutants, he explained.
The complex life of seaweed
In Maine, Paul Dobbins and Tollef Olson are poised to shift their seafood business, Ocean Approved, solely over to seaweed. They are selling their mussel farming operation to focus entirely on a line of kelp products, including sugar kelp packaged as noodles, and two other species cut for salads and slaw. Unlike the seaweed products more familiar to Americans, theirs are cooked, then stored frozen, rather than dehydrated.
But their operation is limited. Ocean Approved takes young, wild plants from beds in the sea from which they have collected for more than 10 years, and raises them on a rig that rests just above the ocean floor. For a farmer on land, this would be like collecting seedlings from the forest and transplanting them into a garden, rather than simply planting seeds. But the millennia-old innovation of sowing one's own crop is not yet available in this field.
"We have no Burpee seed company," said Yarish. "No companies provide the seed stock for any seaweeds."
Yarish and his colleagues are working on a solution using small-business innovation funds from the National Atmospheric and Oceanic Administration, as well as a Connecticut Sea Grant.
The word "seed" is convenient but misleading. Seaweed does not have seeds. However, like land plants, seaweeds have two distinct life phases — a tiny one and the familiar large one. The microscopic stage is the key, and Yarish and Sarah Redmond, a graduate student and former Ocean Approved employee, are figuring out how best to control it, starting with sugar kelp.
A mature brown kelp plant releases male and female spores into the water. These eventually settle, then germinate into tiny plants, which produce eggs and sperm. The sperm locate the eggs and they unite to form a zygote, which grows into the recognizable, mature plant.
Remond and Yarish have just received seed string, sent from Korea, which they wrap around PVC pipes before allowing the spores to settle onto it. Under ideal conditions — light and temperature are very important — tiny kelp plants will be clinging to the string after 14 days. Once the plants reach .04 to .08 inches (1 to 2 millimeters), the young kelp are placed in open water.
This effort is not unprecedented in the United States.
In Hawaii, cultivation of edible seaweed began in the early 1980s, after wild species were depleted by harvesting. In the mid-1990s, Fitzsimmons helped to set up a "hatchery" for the edible red seaweed Gracilaria on Molokai island. Once planted, the Graciliaria is self-replenishing, and Hawaiian aquaculturists now grow it alongside fish and shrimp.
The newest vegetable
Without the capacity to cultivate seaweed, Ocean Approved hasn't focused much on sales, according to Dobbins, the company's president. But he doesn’t sound worried about demand.
"We still have a long way to grow before we have to move over into the mainstream, and at the same time kelp is becoming more mainstream," he said.
In the meantime, they are laying the groundwork. Ocean Approved has trademarked the phrase "Kelp, the virtuous vegetable."
Seaweed is high in fiber, and one study found evidence that seaweed fiber can dramatically reduce the body's fat uptake, so some have suggested adding it to food as a way to address obesity, heart disease, diabetes, cancer and other problems associated with poor, modern diets. Seaweed powder has been proposed as a healthier alternative to salt and monosodium glutamate. Research has also shown that some species or compounds derived from seaweed have antibacterial, antitumor, antiviral and antioxidant effects. They are high in iodine, essential for thyroid function.
Of course, there are also cautions. Seaweeds can absorb heavy metals, most notably arsenic. But the risks, overall, are very low, according to Myslabodski. (There is evidence that carrageenan, a thickener and stabilizer derived from seaweed, can damage the digestive tract.)
As food, seaweed also faces a more mundane challenge in the English-speaking world its name.
Myslabodski finds the "weed" in seaweed problematic.
"Some people tell me it doesn't have bad connotations," he said. "I don't like it."
Seaweeds, or sea vegetables, were once common foods for coastal dwellers. They have been baked into bread in Wales, mixed with raw fish in Hawaii, as well as eaten raw, pickled, dried and prepared in many other ways. Myslabodski prefers to tap into that aspect.
If you show people the end product, it is a very different story," he said.
Editor's Note: An earlier version of this article mischaracterized the nature of the string Redmond and Yarish received from South Korea. This seed string did not contain any plant material.
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