What are they?

Seaweeds are algae that resemble plants but lack branches and leaves but have fronds instead. They create a perfect habitat for thousands of creatures to live in and hide from predators as well as being a food source for sea-dwelling herbivores.

Are they all edible?

There is only one seaweed you need to be cautious of which is high in sulphuric acid called Desmarestia but this grows in deep water so it is unlikely you’ll come across it. All other seaweeds are ‘safe’ but some can be unpleasant in texture and others with too strong a flavour. Seaweeds are fairly easy to identify and most can be found near the shore. There are green, red and brown seaweeds which already helps identify them. Green seaweeds include Ulva lactuca sea lettuce and Ulva intestinalis gutweed, red seaweeds such as Palmaria palmata dulse and Chondrus crispus carragheen/Irish moss and brown seaweeds such as Laminaria digitata oarweed and Laminaria saccharina sugar kelp. Green seaweeds contain high amounts of chlorophyll so tend to live in shallow water and brown seaweeds tend to live in deeper waters – both red and brown seaweeds also contain chlorophyll but also other pigments that help the seaweed photosynthesise with less sunlight filtering through the water.

Are they beneficial to eat?

Seaweeds are high in fibre, low fat, contain few calories and are full of vitamins and minerals. Dulse contains vitamin C, sea lettuce vitamin A and carragheen Chondrus crispus is a good source of protein.

What grows in the UK?

So the top edible UK seaweeds are…

Chondrus crispus carragheen, Irish moss

Laminaria digitata oarweed

Saccharina latissima (Laminaria saccharina) sugar kelp

Porphyra umbilicalis laver (related to nori which is a different Porphyra sp.)

Fucus serratus serrated wrack

Fucus vesiculosus bladderwrack

Ulva lactuca sea lettuce

Ulva intestinalis gutweed

Alaria esculenta dabberlocks

Osmundea pinnatifida pepper dulse

Mastocarpus stellatus false Irish moss

What do you do with it?

Have you tried eating seaweeds? Apart from sushi nori? Vegetarian gelling agents such as agar and carragheen are both seaweeds making a good alternative to beef gelatine. Certain seaweeds are used as thickening agents in ice creams and milkshakes so you have probably already eaten seaweeds without realising it. Seaweeds such as wracks are used in detoxifying baths at spas and have been since Edwardian times.

There is a fantastic article worth reading which is all about dulse, written by Dr Kevin Curran, a biology professor at the University of San Diego – here is the link

You can eat seaweeds in many different ways. Carragheen can be dried or used fresh and simmered in flavoured milks to make blanc-mange desserts. Laver or nori (Porphyra sp.) can be dried out for making sushi, used fresh wrapped around foods such as fish or cooked with water for many hours until it disintegrates and is either spread on bread or mixed with oatmeal and cooked in bacon fat. Sea lettuce is tasty fresh, dried and crumbled over food such as popcorn or wrapped around fish and fried. Gutweed can be dried or fried – make sure you have rinsed all the sand out of it. Kelps such as sugar kelp and oarweed make good crisps by either drying in the oven or deep frying but they do tend to spit!

How do I harvest them?

Seaweeds anchor themselves to rocks with root-like structures so harvest with scissors, making a clean cut so the seaweed can re-generate. Only harvest from clean sources and only perfect looking specimens. Only take what you need and take sporadically so you leave plenty behind for wildlife – remember it acts as a habitat for many creatures. Rinse what you have collected with sea water in situ as you will find small creatures still in the seaweed that you didn’t realise were there. Rinse with cold fresh water before cooking or eating – it is worth noting that fresh water will start the algae’s cell walls to slowly break down so only do this when you are ready to use.  Many can be dried so if you have taken more than you needed then you can often store it for later use.

Green algae

Ulva lactuca sea lettuce – rich in vitamins, plus calcium and magnesium which can help prevent osteoporosis
Ulva intestinalis gutweed – rich in vitamin C and B12

Red algae

Palmaria palmata dulse – good source of dietary fibre
Chondrus crispus carragheen, Irish moss – natural gelling agent
Mastocarpus stellatus false Irish moss – also used as a gelling agent
Osmundea pinnatifida pepper dulse – strong buttery flavour, called the truffle of the sea
Porphyra umbilicalis laver (related to nori which is a different Porphyra sp.) – dried and eaten, or boiled down for hours to make laver bread

Brown algae

Laminaria digitata oarweed – chopped and dried or fried to make crisps
Saccharina latissima (Laminaria saccharina) sugar kelp – naturally sweet due to mannitol
Fucus serratus serrated wrack – used in cosmetics and other toiletries
Fucus vesiculosus bladderwrack  – high in iodine, useful for stimulating the thyroid and helping with weight loss
Ascophyllum nodosum knotted wrack – being studied for anti-cancer
Pelvetia canaliculata channelled wrack – High in vitamin C and selenium, use in stir fries
Sargassum muticum Japanese wireweed – delicious seaweed raw with tasty ‘caviar’ fruiting bodies
Himanthalia elongata – sea spaghetti/thongweed – dried and eaten like biltong or cooked like spaghetti
Alaria esculenta dabberlocks – like Japanese wakame, used to flavour soups, stir fries, etc.