World Oceans Day: Vegetables of the Sea and their Role in Saving the Environment

World Oceans Day is the day to raise awareness about the critical state of the oceans, to highlight their deep connection to our daily lives, and to inspire action to protect and use marine resources in a sustainable way. 

When we talk about the oceans and their protection, we tend to firstly think of whales, sharks, coral reefs or the decline of commercial fish species. However, we often forget the so-called “vegetables” of the sea, in biological terms – algae. These are organisms, which the French plankton specialist and active member of the Slow Fish network, Pierre Mollo calls “small sea people.” They have been, and still are, key to the health of the oceans and human health. 

Photo by Johnny Chen on Unsplash

From the Sea to the Soil 

Everything we see on land has started from the sea. Some 3.5 billion years ago, tiny blue algae (phytoplankton) began to capture sunlight using their chlorophyll to produce their plant tissue (their sugars). To do this, they consumed mineral compounds such as iron or sulphur. As a result, carbon dioxide dissolved in the water and this reaction generated a residue: oxygen. These microscopic algae completely revolutionized the planet. 

It is estimated that algae produce approximately half of the world’s oxygen. In addition, the macroalgae or marine algae, are the main producers of the coastal oceanic ecosystems. The ocean’s amazing and wonderful biodiversity, from invertebrates to crustaceans, turtles to the mighty killer whales, as well as from the fish and other species we depend on for food, to the regulatory functions of the oceans and climate, are highly dependent on algae. 

There are about 25 000 species of algae in the world, of which about 160 species are edible. Algae are organized into four colour groups: green, red, brown, and blue. Their size varies greatly, ranging from microscopic (phytoplankton) to several meters in length (kelps).  

Seaweed: Protagonists of Marine Flora

One of the best-known forms of algae are seaweed – also called sea vegetables. They have been revered as healthy and medicinal food in cultures around the world for millennia. 

Photo by Martin Dawson on Unsplash

The Egyptians fought acne with Posidonia oceanica, the same seaweed that Pope Julius III used to stuff his mattress to keep bedbugs away. The posidonia meadows are essential for inshore fishing, as the fish hide their eggs there.  

On the coasts of Peru, the red seaweed known as yuyo (Chondracanthus chamissoi) is dried and then sold in the inland regions where it is incorporated into soups. As it is rich in iodine, it contributes to the prevention of endemic goitre. A remedy known already in the time of the Incas and still used today. The aborigines who climbed the Andes carried a small leather bag with seaweed around their necks: it provided them with the energetic essence of the food. And their Chilean neighbors did the same with Porphyra columbina or lou-tché de Chiloé. 

In Great Britain, seaweed has been used in markets and kitchens since the Middle Ages. In Wales, the laverbread (in Welsh, Bara Lawr: prolonged cooking of the algae) was used to make cookies that were dipped in oatmeal and cooked in pork belly. Today laverbread is also known in Denmark. In the early 20th century Irish markets sold dehydrated sweet cones (Palmaria palmata) to eat on the street.  

Asia, however, is undoubtedly the largest consumer of seaweed. Although sea vegetables grow along rocky shorelines around the world, it’s a key ingredient in Japanese, Korean and Chinese cuisines. The Japanese alone consume five kilos of dried seaweed a year. 

Nutritious Benefits of Seaweed

Seaweed accumulate a treasure in their tissues. Seaweed have many minerals and some of them, such as calcium, magnesium, iron, phosphorus, potassium, or iodine, in a sufficient quantity can cover a very large percentage of the recommended daily intake. They are foods that provide great diversity and quantity of vitamins: A and C, but also several types of vitamin B, so scarce and necessary nowadays. Some are very rich in protein, thus, they are widely used  in vegetarian diets or diets poor in animal protein. They are also rich in fiber and phytocoloids, substances that favor intestinal mobility. 

As Amanda Swinimer says, a marine biologist and seaweed gatherer on Vancouver Island and part of the Slow Fish network in Canada, seaweed have incredible potential for human health because they contain unique compounds found nowhere else in nature. Many of them are highly sought after for their potential health benefits – mostly in cancer, and chronic diseases prevention

Photo by NOAA on Unsplash

Benefits to the Environment and Climate

Seaweed are also playing another important role. They proved to be useful in reducing greenhouse gases. Adding a small amount of seaweed to the feed of cows and sheep can reduce their methane production by up to 91%. Seaweed are also used to create biofuels, including biofuel for reactors, reducing the need for fossil fuels.  In a world where arable land and healthy soil are rapidly being depleted, seaweed is an important and vital food source with great potential to nourish many people. Seaweed can grow without the need for freshwater or fertilizers and by taking advantage of polluted wastewater from agricultural runoff. As is the case on the Breton beaches of Saint Brieuc: the green seaweed known as sea lettuce (Ulva lactuca) proliferates as a result of intensive agriculture. Through the tributary rivers, nitrates reach the sea, which serve as food for the seaweed and make them grow, ferment and stink for miles around. Swimmers often complain about them, but in reality, the seaweed growth helps to remove the high concentration of nitrates from the water.

  • Did you learn something new from this page?
  • yesno