The diversity of the sea lettuce Belonging to the genus Ulva, sea lettuce is a prominent species of green macroalgae, scattered widely across the vast Baltic Sea region, stretching from the Atlantic waters to the Bay of Bothnia in the Baltic Sea. Owing to its rapid growth and easy reproduction, sea lettuce has piqued the interest of the growing aquaculture industry. Research is ongoing both in Sweden and abroad for utilizing sea lettuce in the food industry and for different biochemical applications.
There are multiple species, but until now it has not been known how many there are and previously only a handful had been identified.
Invasive species identified
“We have studied the biological diversity of the Baltic Sea, Kattegatt, and Skagerak by taking a large number of samples from sea lettuce that we have then conducted
The importance of this survey is significant. Growing sea lettuce as a food source is a rapidly increasing industry, and foreign species risk being spread through simple ignorance. To maintain and protect valuable ecosystems along the coasts, it is important to know which species grow there and to not introduce new species that risk out-competing the native species.
Grow the right species in the right place
“Our study shows that today’s method of identifying species, which is often done by looking at the appearance of green algae, is insufficient for identifying the distribution of the various species. We have not been able to see the real extent of the biological diversity,” says Steinhagen.
The inventory discovered many new species, information that can be valuable when cultivation of sea lettuces is initiated in new places along the coast. It is important to grow the right species at the right place to avoid the risk of impacting diversity.
“This new knowledge allows us to develop methods for maintaining the unique sea lettuce species along a specific coast. Our survey can also help when writing regulations related to invasive species that should not be used in aquaculture if it is to be sustainable,” says Steinhagen.
Facts about sea lettuce
Sea lettuce consists of many species of the green algae Ulva. In Sweden, sea lettuce grows on cliffs and rocks at the edge of water along the entire West Coast and in the Baltic Sea up to the Bay of Bothnia. Sea lettuce is very nutritional with relatively high protein content, healthy polyunsaturated fatty acids, and dietary fibers. It also has valuable biochemical molecules. Research is ongoing both in Sweden and abroad for utilizing sea lettuce in the food industry and for different biochemical applications.
Reference: “Molecular identification of the ubiquitous green algae Ulva reveals high biodiversity, crypticity, and invasive species in the Atlantic-Baltic Sea region” by Sophie Steinhagen, Samanta Hoffmann, Henrik Pavia and Gunilla B. Toth, 5 May 2023, Algal Research.
DOI: 10.1016/j.algal.2023.103132