The Good (Sea)Weed
Excess nitrogen in coastal waters is a major environmental problem on the Cape and other coastal regions of the country, one that federal law—in the form of the Clean Water Act—requires local governments to deal with. The short story on nitrogen pollution is this: nitrogen is in lawn fertilizers and our urine and poop, it is a nutrient, it gets into our groundwater via septic systems, it travels to the coast where it “over-fertilizes” the water, causing nasty algal blooms that block sunlight, deplete oxygen and choke out wildlife. Towns on the Cape are engaged in the difficult process of deciding what solution is best: sewers, decentralized systems, eco-toilets, nitrogen barriers on the coastline, oyster aquaculture, or some combination of them all. Farming seaweed may soon be added to the list.
The win-win hypothesis is that farming seaweed in coastal estuaries lowers nitrogen levels while also providing a healthy, locally grown crop. Since nitrogen is already (over)fertilizing our waters, why not harness those nutrients to grow a crop that people actually want to eat? This is the vision of Woods Hole scientist Scott Lindell, who this summer launched an experiment to test the efficacy of seaweed aquaculture as a nitrogen removal technique.
“I believe in growing systems that don’t produce waste,” Lindell told me when we met this summer to talk about the project. Lindell, 54, is tall and slim, with a general aura of health (when I arrived at his office door he was eating a carrot). How does growing seaweed reduce nitrogen? Lindell explained that seaweeds—like all living creatures—need nitrogen to grow, and so when you harvest the seaweed you’re removing the nitrogen that’s been stored in the plant’s cellular mass. “My question,” he said, “is how much seaweed do you have to grow to [significantly] reduce nitrogen?”
We walked down the hall to his laboratory where the seaweed species Gracilaria was circulating around in large vats of nutrient-rich water. Lindell scooped up a piece of the thin, branching algae and held it out. “Want to try some?” We both munched a sprig. “It’s definitely got a salty, nutty taste,” Lindell observed. “Not as salty as a pretzel but that sea-salty taste that I like.” I found it pleasantly crunchy, without a strong “seaweedy” flavor.
Lindell choose Gracilaria because it is native to Waquoit Bay in Falmouth, where he’s conducting his field experiment. I accompanied Lindell and his colleagues on the day they transferred his stock of Gracilaria to the test site. It was a cloudy morning in late June when we arrived at the dock and processing facility of Washburn Island Oysters at the mouth of the Seapit River in Waquoit Bay. Lindell’s research partner Charlie Yarish, one of the world’s leading seaweed experts and a professor at the University of Connecticut, met us there. Yarish, 64, is jovial and energetic, always with a slight smile around his eyes. “This was my grand idea!” he said. “You have this species that absorbs nutrients: you put it in [the ocean], you take it out, give it a hair-cut—it’s a no brainer!” The technical name for this process is nutrient bioextraction.
Yarish already has two Gracilaria test sites in Long Island Sound and the Bronx River. “The results blew us away,” he said. In the Bronx River the seaweed grew at a rate of 12% per day, doubling its mass every six days. You can’t eat that seaweed because the Bronx River is too polluted and heavy metals accumulate quickly in Gracilaria, but there are other uses for the seaweed, including biofuel production, which, Yarish frowned, “is not my first choice.”
It was Lindell’s idea to try growing Gracilaria in conjunction with oysters. He wants to know if growing seaweed close to an oyster aquaculture operation leads to higher growth rates compared to a non-oyster control site. Oysters clarify the water by filtering phytoplankton, which could allow more sunlight to reach the Gracilaria; they also excrete ammonia (NH4), which Gracilaria soaks up like a sponge. Plus, growing Gracilaria in conjunction with oysters might be more profitable than farming the seaweed alone: an oyster company already has all the necessary equipment, infrastructure, customer contacts and access to a growing site.
This is where Washburn Island Oysters comes in. Another person on the dock that morning was Todd Stressenger, the company’s owner. We all stepped into his boat and he motored us past his shellfish grants out to a long line of white buoys. This was the non-oyster control site. Lindell and Yarish’s research assistant, Jang Kim, hung over the side of the boat while an intern handed them 16 six-foot-long lengths of rope, each strung with several 20-gram bundles of Gracilaria. These Gracilaria ropes were then clipped onto weighted ropes hanging from the buoys at a depth of either one or three feet below the surface.
“We are an oyster company,” Stressenger asserted when I asked if he was interested in growing Gracilaria. “The purpose of our involvement here is just to help Scott with his research project.” Stressenger’s employee Jake Fricke added, “Currently we are way too busy to grow seaweed.” Another goal of the project is to estimate how much work it takes to farm Gracilaria, the labor involved in harvesting and keeping the growing lines clear of drift and fouling organisms. “I want to see the private sector pick this up,” Yarish said, “and to do that, you have to show them that they can make money.”
Certainly, no one will grow Gracilaria if no one is eating it (or buying it for other purposes such as biofuels, animal feed, compost, etc.). “This is all going to be customer driven,” Lindell said. Gracilaria is widely eaten in Asia and Hawaii (Hawaiian weekly demand is estimated at over 2200 lbs), but it’s virtually unknown in the contiguous forty-eight.
Yarish has contacted the Culinary Institute of America to spread the word about edible seaweeds such as Gracilaria, and says he has arrangements with several restaurants interested in buying the product once all the permitting and regulatory issues are worked out. Lindell can’t sell the Gracilaria he’s growing in Waquoit Bay (his research grant prohibits it), but he would like to introduce the vegetable to chefs.
He’s already shared some of the seaweed with Falmouth food writer Patricia Gadsby, who is also a member of the Experimental Cuisine Collective in New York City. “It’s surprisingly crunchy in texture, and surprisingly mild and ‘un-marine’ in taste,” Gadsby wrote in an email. “Raw, the taste reminds me vaguely of nuts and mushrooms. The seaweed looks stunning fanned out on the plate and would make a great garnish for fish.” She’s dried and pulverized a small sample, and is interested in playing around with Gracilaria’s gelling properties, perhaps using it to add more body to fish soups or as a subtle thickener. She boiled some of the Gracilaria and reported that the gel it creates is “very pleasant, soft, silky, with no graininess.”
You can also eat Gracilaria raw in seaweed salads. The “green” seaweed comprising the seaweed salads in most Japanese restaurants and supermarket sushi sections is wakame, a brown seaweed species that has been blanched green and is usually sourced from Asia.
Yarish told me about a chef in Connecticut he’s friendly with, Bun Lai. Lai’s restaurant, Miya’s Sushi, specializes in sustainably sourced seafood. Below each item on the menu is a little blurb highlighting the environmental virtues of each dish. For example, customers read that the Seaweed Miso Soup is “made with wild seaweed grown on our own hundred-acre certified shellfishing farm on the Thimble Islands [off the coast of Connecticut].”
Yarish pointed out that the trend of including sourcing information on menus makes it easier to introduce a new food like Gracilaria that consumers might otherwise not recognize or be inclined to order. Lai’s oeuvre includes dishes using salt from the impoverished Pacific island nation of Kiribati, which, the menu informs, “may become the first nation to be completely engulfed by the ocean due to climate change.”
Lai’s restaurant might not be everyone’s cup of tea, but as far as the Gracilaria project goes, really, from Left to Right, who in America could object to turning pollution into profit?
Elizabeth Saito is a freelance writer. Her forthcoming children’s book about Spohr Gardens in Falmouth will be published this winter. She lives in Falmouth with her husband and son.
