UNDERWATER GARDENS
Growing To Give
Underwater gardens are a veritable treasure trove of potential food sources. From common seaweeds to exotic marine plants, these aquatic ecosystems provide a wealth of nutritious and sustainable food.
Underwater gardens are a veritable treasure trove of potential food sources. From common seaweeds to exotic marine plants, these aquatic ecosystems provide a wealth of nutritious and sustainable food. For coastal communities around the world, sea vegetables have long been an essential part of daily diets, traditional medicine, and cultural identity. Today, as interest in regenerative food systems grows, these underwater forests are gaining renewed attention for their ecological and nutritional value.
Marine plants require no soil, no freshwater irrigation, and no synthetic fertilizers. They grow using sunlight and naturally occurring nutrients in seawater. In a time when land-based agriculture faces soil degradation, freshwater scarcity, and climate stress, underwater gardens offer a powerful complement to terrestrial food systems.
Here, we’ll dive into the world of edible marine plants, exploring their uses, cultivation, responsible wild harvesting practices, and the growing importance of sustainability in ocean-based food production.
One of the most familiar types of underwater food plants is seaweed, which comes in numerous species and types. Seaweeds are broadly categorized into brown, red, and green algae, each offering unique flavors, textures, and nutrient profiles. Some common varieties include kelp, nori, and dulse.
---Kelp: This large brown seaweed forms dense underwater forests along cool coastlines. A staple in many Asian cuisines, kelp is rich in iodine, calcium, magnesium, iron, and trace minerals drawn from seawater. It can be eaten fresh in salads, simmered into broths, dried and powdered as seasoning, or used in soups and stews. Kelp is also used to make kombu, a foundational ingredient in Japanese dashi stock.
---Nori: Nori is the Japanese name for edible seaweed species in the red algae genus Pyropia. It is typically farmed in coastal waters, harvested, shredded, pressed into sheets, and dried. Nori is widely known for wrapping sushi but is also crumbled into rice bowls, soups, and snacks. It provides protein, B vitamins, and essential amino acids.
---Dulse: This red seaweed grows on rocky northern coastlines and has been traditionally consumed in Ireland, Iceland, and Atlantic Canada. Dulse is often dried and eaten as a snack or added to soups and breads. When lightly pan-fried, it develops a smoky, savory flavor. Dulse is notable for its protein content, potassium, and iron.
Beyond the more familiar seaweeds, many lesser-known marine plants and algae are gaining culinary recognition. These species add diversity to coastal diets and represent untapped potential for sustainable nutrition.
---Sea lettuce: This bright green, leafy seaweed grows in intertidal zones and shallow waters. With a delicate texture and mild flavor, it is used in salads, soups, and sushi. Sea lettuce is high in protein, fiber, vitamin C, and iron.
---Samphire (Sea Asparagus): Though technically a salt-tolerant coastal plant rather than a seaweed, samphire grows along shorelines and marshes. Its crunchy texture and natural saltiness make it a popular accompaniment to seafood dishes. It can be lightly steamed, sautéed, or pickled.
---Sea Grapes (Caulerpa lentillifera): These bead-like clusters resemble tiny green grapes and are prized in Southeast Asian cuisines. Sea grapes are eaten fresh in salads or with dipping sauces. They are rich in antioxidants and minerals.
Wild harvesting seaweed can be a rewarding and sustainable practice when done responsibly. However, it requires knowledge, care, and adherence to local regulations. Always research local laws, as permits may be required and certain species may be protected.
Only harvest seaweed from unpolluted areas away from marinas, sewage outflows, industrial discharge, or heavily trafficked harbors. Seaweed absorbs minerals — and pollutants — from the water, so water quality is essential for safe consumption.
Use scissors or a sharp knife to cut seaweed above its holdfast (the root-like structure attaching it to rocks). Never rip seaweed from its base. Leaving the holdfast intact allows the plant to regenerate. Take only a small portion from each patch, typically no more than one-third of what is present.
Do not harvest from eelgrass beds or protected marine habitats. These ecosystems provide essential shelter and nursery grounds for fish and marine life.
After harvesting, rinse seaweed thoroughly in clean seawater at the collection site to remove sand, small shells, or marine organisms. At home, rinse again in cool freshwater to remove excess salt and debris. Inspect carefully for small invertebrates.
Fresh seaweed can be eaten raw in salads, lightly blanched, or added to soups and stir-fries. Store fresh seaweed in the refrigerator in a breathable container or loosely wrapped in a damp cloth. It typically keeps for 3–5 days.
Drying is one of the most effective preservation methods. Lay seaweed in a single layer on clean racks in a well-ventilated, shaded area. Avoid direct sunlight, which can degrade nutrients. Once fully dry and brittle, store in airtight containers away from moisture. Properly dried seaweed can last up to a year.
Blanch seaweed briefly in boiling water for 1–2 minutes, cool quickly in ice water, drain thoroughly, and freeze in portioned containers. Frozen seaweed maintains good texture for soups and cooked dishes.
Some varieties can be pickled in vinegar or fermented with salt, creating probiotic-rich foods that enhance flavor and extend shelf life.
Overharvesting is a significant concern for many edible marine plants. Eelgrass (Zostera marina), for example, is vital for marine biodiversity and water filtration. Removing too much plant material disrupts habitats, increases erosion, and weakens ecosystem resilience. Responsible harvesting practices and marine protected areas are essential for preserving ocean health.
Marine plant aquaculture is expanding globally. One of the leaders in this field is the cultivation of seaweeds like kelp. In regions like Maine (USA), Japan, China, and Norway, kelp farming is a thriving industry.
Kelp farming has significant environmental advantages. It grows rapidly, requires no feed or fertilizer, and absorbs excess nitrogen and carbon dioxide from the water, helping combat ocean acidification and nutrient pollution.
Sea grapes (Caulerpa lentillifera) are also commercially cultivated in shallow ponds and coastal farms, particularly in Southeast Asia. These low-impact aquaculture systems provide livelihoods while reducing pressure on wild populations.
The sea offers a rich array of food sources that are both nutritious and sustainable. As interest in regenerative food systems grows, underwater gardens represent a frontier of climate-smart agriculture. However, exploration and consumption must be guided by respect for marine ecosystems. Responsible harvesting, sustainable aquaculture, and science-based policy are essential to ensure the long-term vitality of these ocean forests.
When managed wisely, underwater gardens can nourish both people and planet — offering food security, ecological restoration, and a deeper connection to the living oceans that sustain us.
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