Seaweeds are macro algae that are essential to marine life for food and habitat, and they have been a key part of the human diet for thousands of years.
Our Irish ancestors relied on seaweed as part of their diet, handpicking it for their families from the edge of the shore. As far back as the 5th century, monastic writings tell of its importance in Irish cooking.
There are three main types of seaweed, based on where we can find them on the shoreline.
Are those found on the upper shoreline and need the most sunlight and air.
Sea lettuce is a commonly used green seaweed. Some scientists claim that these are the real originators of our land based plants.
Are found on the lower shore and have a characteristic red pigment that masks the green chlorophyll and helps identify this group. Dulse is a delicious species of red seaweed that is harvested along the west coast.
Can be found at middle and sub-tidal zones. The deeper the seaweed grows, the darker the colour of their leaves.
Brown species tend to be bigger and grow in large dense forests. Kelp is a very well known brown seaweed and was responsible for the Japanese chemist Kikunae Ikeda discovering the famous ‘fifth’ taste – umami.
The term ‘weed’ is a real misnomer for these marine plants. There are hundreds of different species, more even than the great variety of land vegetables that we are accustomed to.
And each seaweed has its own unique properties, nutrient benefits and flavours.
I know some people may be discouraged by the idea of eating seaweed- but there are so many varieties of flavours and textures to chose from –
I believe there’s something for everyone amongst these sea vegetables.
What are Algae?
Algae are simple plants that can range from the microscopic (microalgae), to large seaweeds (macroalgae), such as giant kelp more than one hundred feet in length.
Microalgae include both cyanobacteria, (similar to bacteria, and formerly called “blue-green algae”) as well as green, brown and red algae. (There are more varieties of microalgae, but these are the main ones.)
Algae can be grown using water resources such as brackish-, sea-, and wastewater unsuitable for cultivating agricultural crops.
When using wastewater, such as municipal, animal and even some industrial runoff, they can help in its treatment and purification, while benefiting from using the nutrients present.
Most microalgae grow through photosynthesis – by converting sunlight, CO2 and a few nutrients, including nitrogen and phosphorous, into material known as biomass This is called “autotrophic” growth.
Other algae can grow in the dark using sugar or starch (called “heterotrophic” growth), or even combine both growth modes (called “mixotrophic” growth).
Algae are very diverse and found almost everywhere on the planet.
They play an important role in many ecosystems, including providing the foundation for the aquatic food chains supporting all fisheries in the oceans and inland, as well as producing about 70 percent of all the air we breathe.
What is the difference between Seaweed and Algae?
Seaweeds are a group of algae, and have some special characteristics viz. macroscopic, multi-cellular, benthic, and marine.
Diversity of algae is extremely high and incomparable with that of seaweeds.
Algae could be both unicellular and multi-cellular, whereas seaweeds are necessarily multi-cellular.
All the seaweed species are autotrophic, whereas some algal species rely on other external food materials.
Algae inhabit both freshwater and marine waters, while seaweeds inhabit only seawaters.
Marine algae can distribute over shallow as well as deep waters, while seaweeds mostly inhabit shallow waters.