Along the rugged coastline of Cornwall, hidden underwater treasure troves thrive: seaweed. Often overlooked, yet crucial to our ecosystems. 

Cornwall’s shores have an astonishing variety of these marine algae, each playing a crucial role in the underwater world. More than just an oceanic plant, seaweed is a cornerstone of marine life. 

With Cornwall’s unique interplay of the Atlantic currents and rocky coastlines, there are more than 500 species of seaweed, ranging from towering kelp forests to delicate fronds adorn the shallows. 

Below, we’ll explore what seaweed is and what species are more well-known around Cornwall.

What is Seaweed?

Seaweed belongs to a category known as algae, representing a fascinating and diverse group of marine flora. They’re incredibly varied in form and function, leading them to be classified by colour rather than botanical classifications. 

Seaweed is a habitat for sea creatures, a food source and a vital contributor to oceanic health. It’s the unsung hero of the sea, performing photosynthesis and producing oxygen. Due to their density, they often provide shelter and sustenance to marine organisms. 

That said, seaweeds are not “true” plants. While they perform photosynthesis, they lack land plants’ typical root, stem, and leaf structures. Instead, it possesses a holdfast, rool-like structure that anchors them to rocks, the ocean floor, or fronds – leaf-like structures that absorb nutrients and light. 

Seaweed diversity is astounding, with each type playing its unique role in the ecosystem. This diversity is especially prevalent along the Cornish coastline, where a mix of temperate waters and rocky habitats creates the ideal conditions for a range of seaweed species. 

Seaweeds of Cornwall

Cornwall’s seaweeds add to the region’s natural beauty and marine biodiversity. There are a lot of seaweed species, but let’s dive into some of the notable ones that can be found along this British coastline:

Oarweed (Laminaria digitata)

This common kelp species, with its large, leathery, dark browny-green fronds, forms dense underwater forests at high tide. Oarweed is vital for marine life, providing habitat for numerous small species​​.

Sugar Kelp (Saccharina latissima)

Identifiable by its single large brown fronds and distinctive wavy edges, sugar kelp thrives in sheltered spots, playing a crucial role in the marine ecosystem​​.

Sea Spaghetti (Himanthalia elongata)

Resembling long, browny strands of spaghetti, sea spaghetti is an edible seaweed that grows up to six feet in length and is often found in mats on the water’s surface.

Rainbow Wrack (Cystoseira tamariscifolia)

A small, spiky seaweed rainbow wrack thrives in shallow waters. It is renowned for its vivid blue, purple, and green hues, which are brightest in spring​​.

Bladder Wrack (Fucus vesiculosus)

Easily recognised by its olive-brown fronds with air-filled bladders, bladderwrack is one of the most common seaweeds and is essential for many marine organisms​​.

Sea Lettuce (Ulva lactuca)

This common seaweed, resembling a lettuce leaf, is found in rockpools and floating in mats. It’s edible and known for its thin, translucent green appearance​​.

Gutweed (Ulva intestinalis)

Also known as grass kelp, gutweed forms bright green carpets in shallow waters and rock pools. It’s an edible seaweed often used in culinary preparations​.

Dulse (Palmaria palmata)

Dulse, known for its savoury, slightly smokey flavour, is a red seaweed often used in cooking. Its flat red fronds are a culinary delight and a common sight along the Cornish coast​​.

Among the hundreds that adorn Cornwall’s coast, these species contribute to the region’s marine ecology and play a significant role in local industries and cultures.

Preserving Cornwall’s Wonders

Cornwall’s coasts hold more than just beautiful sights. With a prevalent seaweed ecosystem and careful preservation of its resources, Cornwall holds host to a thriving marine life. 

We take pride in working with local Cornwall councils to select and extract waste seaweed along Cornwall’s coasts carefully. Upon removing, we help keep Cornwall’s shores pristine and beautiful while ensuring the highest quality and nutrient-rich content is used for our fertiliser. 

We believe in creating a sustainable and vibrant relationship with our plants, and the first step on that journey is appreciating and respecting where our ingredients come from. 

You can grab your hand-picked, hand-pressed Cornwall seaweed fertiliser over at our shop and give your plants a boost of nutrients. 

Let’s continue to celebrate and preserve Cornwall’s marine wonders, recognising the crucial role seaweed plays in our local and global ecosystems.

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