I still remember the first time I swam through a kelp forest. I was 21, free-diving off the coast of British Columbia. As I descended into the cool Pacific, the sunlight fragmented through towering golden-brown fronds, revealing an underwater cathedral swaying gently in the current. Fish darted through the foliage, sea stars clung to rocks below, and in that moment, surrounded by the rhythmic pulse of the sea, I felt something ancient and alive envelop me. It was the first time I truly grasped how powerful and interconnected ocean ecosystems are—and how kelp, often overlooked, plays a starring role in the ocean’s health and possibly in ours, too.

What Exactly Is Kelp?

Kelp refers to a group of large brown macroalgae in the order Laminariales. Though they resemble plants, kelp are not true vascular plants—they belong to a separate group of photosynthetic organisms called stramenopiles, more closely related to diatoms than to terrestrial vegetation. They grow in underwater “forests” in cold, nutrient-rich coastal waters around the globe.

Structurally, kelp has:

Holdfasts: root-like structures that anchor it to the seabed

Stipes: stalk-like stems that give it height

Blades: leaf-like structures that perform photosynthesis

Pneumatocysts: gas-filled bladders that help the blades float toward the surface to maximize sunlight absorption

Some species, like Macrocystis pyrifera (giant kelp), can grow over 60 meters long and up to 50 cm per day under optimal conditions (Mann, 1973). This remarkable growth makes kelp one of the most productive organisms on Earth.

From Seaweed to Solutions: Uses of Kelp

Kelp has been used for centuries as food (e.g., kombu in Japan), fertilizer, and even medicine. It’s rich in iodine, calcium, magnesium, iron, and antioxidants. But recent innovations are opening up new industrial possibilities for this ancient seaweed—particularly as a sustainable resource to replace petroleum-based plastic.

Kelp as a Plastic Alternative

Kelp contains compounds like alginates, agar, and carrageenan, which are natural polysaccharides used to create gels, films, and binding agents. These are biodegradable, compostable, and non-toxic, making them ideal for replacing conventional plastics in packaging and disposable products. Companies like Notpla (UK) are already commercializing seaweed-based packaging, creating edible water pods and biodegradable takeaway containers. Their product, Ooho, made from brown seaweed and plants, completely degrades within 4–6 weeks—unlike plastics, which persist for centuries. Notpla won the Earthshot Prize in 2022 for their work.

The SEABIOPLAS project (EU-funded) explored seaweed as a feedstock for bioplastics. They cultivated species such as Alaria esculenta and Gracilaria vermiculophylla in integrated aquaculture systems to produce sustainable, marine-derived bioplastics (SEABIOPLAS, 2015). The process required no land use, no freshwater, and no synthetic fertilizers—setting it apart from other bioplastic feedstocks like corn or sugarcane.

According to research by van den Burg et al. (2020), bioplastics derived from macroalgae offer lower greenhouse gas emissions, faster biodegradability, and reduced ecological impact compared to traditional plastic.

Ecological Benefits of Kelp FarmingKelp farming, unlike most forms of agriculture, is inherently sustainable. It doesn’t require arable land, freshwater, fertilizers, pesticides or artificial inputs. Instead, kelp grows by absorbing sunlight, CO₂, and nutrients from seawater – acting as a natural carbon sink. A study by Krause-Jensen & Duarte (2016) estimated that global kelp forests could sequester up to 173 million tonnes of CO₂ annually, potentially contributing to climate mitigation.

Additional benefits include:

Reducing ocean acidification: Kelp absorbs CO₂ and releases oxygen, helping buffer acidic conditions that threaten shellfish and coral. Improving water quality: In integrated multi-trophic aquaculture (IMTA), kelp absorbs excess nitrogen and phosphorus from fish farms, reducing eutrophication.

Providing marine habitat: Kelp forests are biodiversity hotspots that support fish, crustaceans, mollusks, and even mammals like sea otters. Kelp farming also provides economic opportunities for coastal communities without the ecological toll of industrial fisheries or land-based agriculture.

Organizations like GreenWave in the U.S. are pioneering regenerative ocean farming, combining kelp with shellfish to create zero-input systems that clean the water and restore marine ecosystems. Their “10-year, 10,000 farmers” plan envisions a vast network of ocean farmers who can feed local communities while drawing down carbon.

Conclusion: A Forest Beneath the Waves

What began for me as an awe-inspiring dive into a kelp forest became a lasting connection to one of nature’s quietest but most powerful forces. Kelp is more than seaweed—it’s a renewable, regenerative, and multifunctional resource that can help solve problems ranging from plastic pollution to climate change. As research advances and industries adapt, kelp could play a crucial role in a sustainable, ocean- friendly future. Perhaps it’s time we looked beneath the surface – not just of the sea, but of our assumptions – because there, among the long green blades, hope is growing.

An Article by Malia Lukl