Seaweed is the collective name for macroscopic marine algae. There are three groups of seaweed including red, brown and green. Seaweeds make their own food by photosynthesis using light-harvesting pigments, which give each group its distinctive colour. All seaweeds all contain chlorophyll but brown seaweeds also contain brown pigments while red seaweeds red pigments.

There are about 6000 red, 1500 brown and 1000 green species of seaweed in the world. Around the UK, there are over 650 species of seaweed.

Egg wrack (Ascophyllum nodosum), also known as knotted wrack, is a tough, long and leathery seaweed with compressed fronds that can grow up 30-150 cm long and up to 1 cm wide. The fronds branch in an irregular, evenly forked pattern and attached to rocks by a disc-shaped holdfast. 

A distinctive feature of this seaweed is its egg-shaped air bladders which grow along the fronds, often one per year. Air bladders act as flotation devices, allowing sunlight to reach the seaweed better and aiding photosynthesis. You can estimate egg wrack’s age by counting its bladders. Egg wrack can live up to 15 years.

Where can you find it? 

Egg wrack prefers sheltered shores. Their distribution is affected by salinity, wave action, and temperature. On Alderney, you can spot it mid-shore at Longis, Clonque and Braye bays.

Why is it a key species?

Egg wrack is one of 42 key species of Alderney. This seaweed is commercially and ecologically valuable. 

• Egg wrack is highly effective in absorbing nutrients and minerals from surrounding water and it indicates contamination in the environment. Examining the number of heavy metals found in their fronds can reveal how polluted an area of water is.
• Egg wrack provides nursery grounds for a variety of commercially valuable fish out of which the most common ones include pollock (Pollachius virens), bull rout (Myoxocephalus scorpius) and Atlantic cod (Gadus morhua).
• Egg wrack, alongside other seaweeds, is globally heavily used for commercial purposes. Egg wrack has been exploited for use in products such as food, fertiliser (They can boost crop resilience to stress, enhance soil health and help farmers to increase yields), soil conditioners, biostimulants (to boost plant defense mechanisms against pathogens), animal feed, skin and hair care products, cleaners, de-greasers, equestrian products and nutritional supplements (because of their high carotenoid content and anticancer activity). It is also used in cosmetology and thalassotherapy (seawater-based therapy). 

More cool facts:

• Seaweed grows from the base, not the tip like plants on land, so young and growth area of a frond is at the bottom and oldest part at the top. (Surey-Gent & Morris, 2000, p.16)
• The Vikings harnessed the tide and harvested egg wrack to feed their livestock and nurture their crops and soil.
• Vraic means seaweed in Guernésiais, the local language of Guernsey. From the 16^th century, vraic was collected by farmers to enrich soil. Vraic harvest was regulated, including when and how it could be harvested. Today, vraic is still collected for the same purpose. In the Channel Islands, it is gathered and left to dry naturally on land to reduce soil acidity.
• Vraic was also used as food by islanders to survive famine during the WWII. Vraic was boiled and made jams and jellies. Learn more about Guernsey vraicing here.