We mentioned seaweed in last month’s newsletter on restorative aquaculture and this month we’re going to focus on this group of aquatic plants. In the U.S., seaweed production has taken off in the past few years, mainly around New England, the Pacific Northwest, and Alaska. In Maryland however, seaweed aquaculture is still emerging, with the majority being grown as an experimental practice in the Chesapeake Bay, rather than for commercial production.
However, seaweed can be used not just as a food source, but also in things like cosmetics, animal feed, and fertilizer. Compared to many aquaculture species, seaweed is relatively easy to take care of and can be grown in such a way as to make full use of the entire water column. That is to say, being able to fill the entire vertical space in an aquaculture lease, not just using the bottom or surface of the water.
In many parts of the world, seaweed forests are a natural coastal feature. Besides being food for humans, seaweed is also food and habitat for animals. This makes it very important to our commercial fisheries, not just as a product itself, but as something which enables the production of other wild species of fish.
Seaweed also happens to be great at absorbing carbon dioxide, so it’s being looked at as something that can help offset greenhouse gas emissions. The excess carbon in the atmosphere increases the amount of carbon dissolved in the ocean, which results in decreasing pH. This means the water becomes more acidic, which ultimately affects animal life. The more seaweed produced, the more carbon removed from the atmosphere and the water, and the happier our oceans will be.
In addition, seaweed can do more than just absorb carbon. It is also capable of absorbing excess nutrients like nitrogen and phosphorus. Nitrogen and phosphorus are primarily what is responsible for the dead zones that form in the Chesapeake Bay. By absorbing these nutrients, seaweed is taking them away from other algae that grow out of control and make the Chesapeake Bay less healthy.
As for seaweed for food, you might already be eating seaweed without even knowing. Carrageenan, a common thickening agent, is derived from the red algae, Irish Moss. It is a vegan alternative to gelatin and can be found in commercially made ice cream, dairy-free milks, sauces and is even used to make beer less hazy. And while some suggest this ingredient should be avoided due to health concerns, there are no clinical studies to support this.
Other edible seaweed includes nori for sushi, wakame for seaweed salad, or kombu for miso soup. Some species like dulse can be used as a vegan alternative to bacon and sea lettuce can be used raw in salads like regular (but saltier) lettuce.
Of course, aquaculture is always changing, but looking into the future, there appear to be two main directions for seaweed production; production that is part of restorative aquaculture where the seaweed will eventually be harvested, and that which is planted purely to improve the health of our coastal ecosystems.
Next time you take a bite out of this salty sea veggie, do so with newfound gusto!