Sea lettuce on a rock platform in coastal Australia

Ever walked along the coastline and wondered about all of those seaweeds?

Are they edible? How do you harvest them? How do you positively identify them? Are you allowed to collect them?

A great (and yummy) seaweed that’s an easy one to start with is sea lettuce. You know it, that bright green algae sprouting from rock platforms, visible at low tide. But first, to answer the burning question of ethics and legalities.

Seaside legalities and ethics

The specifics of coastal ecology regulations change from state to state. You also need to be aware that legislations change and the boundaries of protected areas shift. The range of permission varies from being completely unregulated outside of marine reserves or national parks, to a clearly defined limit for personal use, or to the need for a harvester’s licence. Please consult with your local council with regard to your current regulations. I have written an overview of the legalities, from state to state, in an article here.

As a general rule, never pull seaweeds form their ‘holdfast’. The holdfast is the root-like structure at the base of the seaweed that anchors them to a stable surface, such as rock, or the seabed (seaweeds do not have a root system, as they take up nutrients from sea water through their fronds). Instead, harvest by cutting, leaving behind the holdfast so that the seaweed can regenerate – or better still, collect seaweed when it has washed ashore.

Please note that seaweeds are important not only when they are alive in the water, but also when they are decaying on the beach. They are a vital element in marine ecosystems, existing at the lower level of the food web. Fish, birds, snails, crabs and marine mammals use kelp beds for food, refuge or spawning, or as nursery grounds so please make sure you only take a fraction of what’s there.

Finally, please be aware that it is best not to harvest from the beach straight after a storm. Particularly in built environments, storm channels will carry to the shore the debris of the city, polluting the water and everything in it.

Sea lettuce
Ulva lactuca

Sea lettuce is a ‘cosmopolitan’ seaweed – growing all over the world. It can be found all around Australia on rock platforms in the intertidal zone, the part of the seashore that is above water level at low tide and underwater at high tide. You will need to look for it at low tide when it’s clearly visible and acessable.

In Australia it is much appreciated by fishermen, who use it as bait for blackfish (luderick).

Always be careful where you harvest your sea lettuce, making sure that the surrounding area is clean, and has a great tidal exchange and fast currents. Always make sure to cut the sea lettuce fronds, leaving the holdfast behind to regenerate.

How to identify sea lettuce

Sea lettuce is a thin, flat, green seaweed growing from a round holdfast, forming expansive mats several metres wide. The frond resembles a leaf of lettuce. You will find big colonies of this seaweed growing closely together in rock pools or on flat rock platforms that are regularly washed by waves.

The margins of sea lettuce fronds are somewhat ruffled and are often torn. Fronds may reach 18 centimetres in length and up to 30 centimetres across, though generally they are much shorter. Translucent, and bright green to dark green in colour, the fronds turn white or black when dried out or dead.
See the video for some visuals of a harvesting location and how to dehydrate sea lettuce.

How to eat sea lettuce

Like lettuce grown on land, sea lettuce can be used raw in salads. It can also be cooked and added to soups. I like to quickly sauté sea lettuce with sesame oil and a dash of lime juice, roll it in rice paper with sliced cucumber and rice noodles, and then serve it with a chilli sauce.

Sea lettuce and macadamia rice paper rolls

A Sydney seaside twist to an Asian fast-food favourite. These rolls are healthy, fresh and fun to make with kids. Set up a rolling station and away you go. These lend plenty of room to create your own version with things like avocado strips, julienne vegetables and grilled tofu. Recipe thanks to Marnee Fox.

Makes 8 rice paper rolls

Ingredients

60 g rice vermicelli or rice noodles
2 cups sea lettuce, washed and chopped
2 tablespoons fresh lime juice
1 tablespoon sesame oil
8 rice paper wrappers
½ cup roasted and roughly chopped macadamias
2 large iceberg lettuce leaves, chopped finely
1 tablespoon sweet chilli sauce – plus extra, to serve

Method

1. Bring a medium saucepan of water to the boil. Add rice noodles and boil for 3–5 minutes, or until al dente, then drain. Rinse thoroughly with cold water so the noodles don’t stick together. Leave them to cool.
2. Clean the sea lettuce of any sand or sea life, trim into smallish pieces and sauté in a shallow pan with a dash of lime juice and sesame oil until it becomes soft. Set aside and allow to cool.
3. Mix all the ingredients, except the rice paper wrappers, in a large bowl.
4. Fill a large shallow bowl with hot water. Place a wet tea towel on the work surface nearby. Dip one wrapper into the water for 10 seconds to soften. Lay the wrapper on the wet tea towel and place a handful of the noodle mix across the centre, leaving about 5 centimetres of the wrapper uncovered on each side.
5. Fold the uncovered sides of the wrapper inwards, then tightly roll to enclose the filling. Repeat with the remaining rolls.
6. Serve fresh with sweet chilli sauce.

How to dehydrate sea lettuce

You can also dehydrate sea lettuce, to create a versatile ingredient to use in your kitchen. Either rehydrate to add to dishes or use it dried to make seaweed salt, which can be sprinkled over your favourite dishes.

Nutritional value of sea lettuce

Sea lettuce is an amazing source of nutrients. It is made up of 28 per cent protein, comprising all nine essential amino acids, including lysine, which is often lacking in a vegetarian diet. The pigments found in this seaweed have a high concentration of chlorophyll, as well as strong antioxidant properties.

Sea lettuce is rich in magnesium, potassium and calcium – essential elements for human health and nutrition and is also rich in essential vitamins: Vitamin A, B and C. It is especially rich in Vitamin B-12, which is particularly important in vegetarian diets.

Nutritional analysis.

100g Fresh sea lettuce contains:
Energy 39.4 kcal; Protein 5.1g; Dietary Fibre 6.1g; Carbohydrates 0.99g; Total Fat 0.3g; Sodium 220mg; Calcium 104.72 mg; Iron 0.85 mg; Magnesium 382.21 mg; Zinc 0.562 mg; Potassium 346.08 mg; Manganese 2.53 mg; Vitamin B1 0.03 mg; Vitamin B2 0.85 mg; Vitamin B3 0.67 mg; Vitamin B5 0.224 mg; Vitamin B6 0.066 mg; Vitamin B12 0.437 μg; Vitamin C 3.504 mg; Lutein 6.8 mg; Beta-Carotene 0.933 mg; Zeaxanthin 0.035 mg; Iodine 3.68 mg; Lysine 0.19 mg.`

NOTES: Seaweed “blooming” under certain environmental conditions, is often reported by the media due to vast amounts of algae produced.
In 2009, a bloom of Ulva species hit the headlines as vast quantities of the seaweed were washed up on the shores of Brittany, France. The rotting seaweeds, as with any rotting plant material, produced noxious gases. It was these gases that rendered a horse rider unconscious and killed his horse. On the same beach, and in a separate incident, a man and several children died while taking part in the clean up the green algae, as they were not wearing protection. This bloom was blamed on excessive use of fertilizers and run off from the surrounding farming land. Always be careful where you harvest your sea lettuce from, making sure that the surrounding area is clean, has a great tidal exchange and fast currents.

Reference

Wikipedia> On sea lettuce
Atlas of Living Australia> Distribution range of sea lettuce in Australia
Irish Seaweeds> The review of sea lettuce form the Irish seaweeds database
Saveg.com > 7 Potential Benefits of Eating Sea Lettuce Seaweed
Milkwood > Foraging+Eating Sea Lettuce
Green Dean > On sea lettuce
Eat the Planet > On sea lettuce
Science Direct > Medicinal profile of sea lettuce

How to harvest, cook and eat sea lettuce