Ulva
size:
15-50 centimeters long
shape:
flat ribbons of variable shape
- Dut: Zeesla
- Lat: Ulva spp.
- Eng: Sea lettuce (Ulva, Green laver)
- Ger: Meersalat
- Dan: Søsalat
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- , Oscar Bos
Ulva
Ulva, also known as sea lettuce, is very common in the tidal area of the North Sea. This green semi-transparent seaweed begins to grow in April and can reach an incredible size within a few months (up to 1 square meter on tidal flats). Sometimes you see what looks like toilet paper on the flats or in the flood mark on the beach. In most cases, it is dried up ulva that has been bleached by the sun. Ulva is able to decrease acidity in seawater, making it an important marine 'plant' for combating acidification which is a threat to coral reefs.
- Floating lettuce
- , Sytske Dijksen, www.fotofitis.nl
Free-floating ulva has no problem growing further. Due to its immensity, it easily breaks loose from its holdfast and the entire thallus can be found floating around in the water. Banks of this drifting seaweed can form in late summer, which can be detected by its awful smell.
- Healthy and useful
- Ulva, foto fitis, sytske dijksen
Ulva contains lots of minerals and vitamins, such as magnesium, calcium, vitaminen A, C en B12. It is eaten in many countries or processed in food. However, this is not the seaweed used for making sushi. That is purple laver. Ulva is also used to purify wastewater from biogas power plants. There are several companies in the Netherlands experimenting with ulva for all kinds of new applications.
Because ulva can neutralize acid in seawater, it is important for coral reefs as well as for shellfish and all other animals that need calcium to grow.
See also
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