Seaweed Agriculture & Its Environmental Benefits

Seaweed aquaculture has been growing rapidly over the past decade, now averaging over 35 million tons produced per year worldwide. Aquatic macroalgae are easy to grow, very adaptable, and serves great benefits for ocean ecosystems. Seaweed has many uses including food, farming, climate change mitigation, and biodegradable packaging.

Seaweed, because of its high water content, is low in calories, but, depending on species, is rich with carbohydrates (25%–50%), protein (7%–15%), and lipids (1%–5%). Some edible species include dulse, bull kelp, sea lettuce, and hijiki, which also contain amino acids that are essential for our health. Seaweed is also full of polysaccharides, that can be added to prebiotic supplements to promote gut health.

Seaweed is not only nutritious, but it is also easy and efficient to grow. It does not require fertilizer, pesticides, fresh water, or land. It grows fast and can be ready to harvest in six weeks’ time. Seaweed is farmed using a water column, in which farmers use a process called vertical farming to maximize the harvest from a small area. Most seaweeds grow on ropes hung vertically in the water and stay there through the winter. When harvested in the spring, they will normally reach lengths of 10 feet or more. According to BBC, 48 million square kilometers of the world’s oceans are suitable for seaweed cultivation, making it an easily accessible option as there is no shortage of space.

On the environmental side, seaweed also checks off boxes as a large sequester of carbon dioxide. While people’s first reactions are to turn to land forests, kelp forests also have the potential to be our world’s carbon sinks. Kelp forests absorb sunlight, carbon dioxide, and water to produce sugar and oxygen to grow via photosynthesis. Kelp can grow up to 30 meters tall and up to 61 centimeters per day, approximately 20–30 times quicker than fodder crops. Their rate of growth indicates higher rate of photosynthesis, so more carbon dioxide is absorbed by the plant. Additionally, when kelp dies, most of the carbon dioxide absorbed by its tissues is transported to the ocean floor. A study by Nature reported that Australia’s Great Southern Reef sequesters 1.3–2.8 teragrams of carbon annually, amounting to more than 30% of total carbon stored and sequestered around the Australian continent. The BBC also reported that seaweed is thought to sequester nearly 200 million tons of carbon dioxide each year—as much as New York State’s annual emissions.

Besides absorbing carbon dioxide, seaweeds are also known to suck up large amounts of nitrogen and phosphorus. Considering the large amounts of aquaculture waste and large algae blooms that span hundreds of square miles, seaweed could help clean the waters. Algae blooms are caused by rich runoff and excessive nutrients in the waters, which seaweed can help sequester in certain zones, namely the Gulf of Mexico and Chesapeake Bay, there is excess nitrogen and phosphorus from stormwater runoff and spills. Seaweed farms and forests can help lower the nutrient levels in the surrounding water and control algae growth.

Seaweed can also help wildlife. It acts as a home to many types of fish and ocean organisms. It can be used to soak up pollutants and bring back diverse ecosystems that have been driven away by pollution. Additionally, seaweed polysaccharides could be used to develop eco-friendly, biodegradable packaging material. This would help decrease the amount of synthetic plastics used in our daily lives.

Naturally occurring kelp forests support diverse ecosystems, while farmed seaweed that benefit our health and our planet. The many uses of seaweed and its potential benefits for both humans and the environment should not go unnoticed. Ongoing research and development of seaweed aquaculture could be key to this planet’s future, stabilization, and sustainability success, as long as we prioritize its research and conservation efforts.