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Discover the magical world of seaweeds


Coastal and estuary

Seaweeds are macro 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.

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. This seaweed also gives itself away as it bleaches other harvested seaweeds and also turns an unusual teal colour. 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 sea lettuce (Ulva lactuca) and gutweed (Ulva intestinalis) (and other species), red seaweeds such as dulse (Palmaria palmata) and carragheen/Irish moss (Chondrus crispus) and brown seaweeds such as oarweed (Laminaria digitata) and sugar kelp (Saccharina latissima). Green seaweeds contain high amounts of chlorophyll so tend to live in shallow water but not all (as some of the deep water species are green seaweeds). Brown seaweeds tend to live in deeper waters and are often thick being able to withstand rough seas. Both red and brown seaweeds contain chlorophyll but also other pigments that help the seaweed photosynthesize with less sunlight filtering through the water.

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 is a good source of protein.

The top edible UK seaweeds are…
carragheen, Irish moss (Chondrus crispus)
oarweed (Laminaria digitata)
sugar kelp (Saccharina latissima synonym Laminaria saccharina)
laver (Porphyra umbilicalis) (related to nori which is a different Porphyra sp.)
serrated wrack (Fucus serratus)
bladderwrack (Fucus vesiculosus)
sea lettuce (Ulva lactuca)
gutweed (Ulva intestinalis)
dabberlocks (Alaria esculenta)
pepper dulse (Osmundea pinnatifida)
false Irish moss (Mastocarpus stellatus)
sea spaghetti (Himanthalia elongata)

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 realizing it. Seaweeds such as wracks are used in detoxifying baths at spas and have been since Edwardian times.

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!

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 realize 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.

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

dulse (Palmaria palmata) – good source of dietary fibre
carragheen, Irish moss (Chondrus crispus) – natural gelling agent
false Irish moss (Mastocarpus stellatus) – also used as a gelling agent
pepper dulse (Osmundea pinnatifida) – strong buttery flavour, called the truffle of the sea
laver/nori (Porphyra species, Pyropia species) – dried and eaten, or boiled down for hours to make laver bread. True nori comes from Pyropia yezoensis and P. tenera

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

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