09 June 2022

Focus on the inconspicuous: Sea lettuce - The future of aquaculture - 3

While classifying the benefits we derive from the sea in herbal forms, it is a great injustice to the sea that we concentrate on certain varieties in product focus. We are examining more and more closely the target of releasing a few species, which have been researched and especially highlighted with their benefits for human consumption, in the form of commercial products, and we try to highlight other benefits that we can derive from them as opportunities.

There are many other species that live under the ocean and that we can definitely derive similar benefits from other seafood, regardless of the purpose, when they are above on the water surface. While seaweed is an inclusive seafood among people who adopt a vegetarian and vegan diet, it is very suitable for consumption with sushi and pasta. However, it is very important that we start to recognize other seaweeds other than the varieties such as single-cell ones Spirulina and Chlorella from blue-green algae or kelp from brown seaweeds.

Ulva spp is a seaweed that can live naturally in Turkey's coastal waters as well as in the world's oceans and it is classified as a macroalgae. It is a seaweed that attracts your attention and is easily distinguishable when you see it with its bright green, curved leaves. For this reason, it is also called sea lettuce. It is a very tolerant, perennial species that spreads easily and quickly in waters rich in nitrogen and phosphorus, shallow, with plenty of light and rocky bottom, where there are few herbivorous species that can consume it. The contribution of the photosynthesis ability of zoospores and gametes to its rapid spread is great. In this way, when they cling to a surface, they quickly cover the area. This algae can live both in salty sea waters and in brackish waters mixed with sea water and fresh water.

Ulva is a large family that includes different species. It is known that 25% of the seaweed species harvested all over the world are made from this family. Although it varies according to the region where it is grown and harvested, it is best harvested at the end of summer by taking advantage of its accelerated growth in summer. 

Ulva is a remarkable seaweed with good Vitamin B content considering for human consumption. It is also good in terms of protein, fiber and iron. It contains high amounts of cobalamin, or more commonly known as Vitamin B12, which plays an important role in maintaining homeostasis in the brain and nervous system and in blood production. Thanks to its high mineral content, its high bioaccumulation ability is understood. It contains 87 mg of iron and 700 mg of calcium in a 100-gram serving. It is also remarkable in terms of sodium, calcium potassium, phosphorus, magnesium, iodine, aluminum, manganese and nickel. It also contains Vitamin A, Vitamin B1, Vitamin C, soluble nitrogen, and a large number of trace elements. [Link ↗] According to the results obtained as a result of the examination of the samples collected from the Tunisian coast, 54.0% fiber, 19.6% mineral, 8.5% protein and 7.9% lipid were found in the powder of  Ulva lactuca. Neutral fibers are specified as 20.6% hemicellulose, 9.0% cellulose and 1.7% lignin content. [Link ↗]

The sea lettuce's leaves collected from the sea are washed in fresh water and consumed fresh or dried in the Far East countries. This may bring to our minds Ulva, the lettuce (land based one) that we often consume fondly and hungrily in our society. Ulva is a good suggestion to use as a substitute for lettuce in the Far East. Moreover, associating seaweed consumption directly with Far Eastern cuisine is now a very old-fashioned approach; every cuisine that has direct interaction with the sea, especially the Mediterranean and  cuisine, continues to evolve in a way that takes its share directly from seaweeds.

Considering our practical, healthy and at the same time economical nutritional needs, it is one of the good things we will see in the future that more algae are introduced into people's diets. It is also possible for us to adapt algae to our traditional diet by drying and pulverizing them instead of consuming them directly. A glamorous green cake or useful biscuits with seaweed for our children are just two of the examples we can give.

Improving the environment with the power of the oceans

To think of seaweed only for direct human consumption is a very important misconception that limits our horizons. Researchers from Ege University in Izmir, Turkey, have a comprehensive article on the use of Ulva riliga as a food source in the production of the bean plant, which occupies an important place in human nutrition and is often consumed in geography, and this research is the first to seek answers to the availability of this seaweed in agricultural production in Turkey. [Link ↗]
 
In addition, due to its vitamins, minerals and other nutritional values, Ulva, typically like other seaweeds, produces cosmetics; it is even considered as one of the raw materials of the paper industry. Also in Turkey, the results of another study published by researchers from the Faculty of Fisheries of Çanakkale Onsekiz Mart University try to understand the seasonal nutrient composition of this algae by examining the seasonal nutrient content of Ulva ridiga.
 
One of the biggest causes of the climate crisis we are experiencing today is the amount of carbon, which is increasing day by day and directly affects the water as well as the air. One of the right ways to absorb and recycle carbon, which forms gaseous compounds with oxygen in the form of carbon dioxide or carbon monoxide, and forms acidic compounds by combining with hydrogen, is to use seaweeds in this work. Ulva is a good example that comes to our aid at this stage as well. A study published in a 2017 issue of Global Change Biology Bioenergy provides comprehensive analysis of the carbon capture capacities of seaweeds placed at different levels.
 
In a different part of the world, the same seaweed was placed in tanks with sea bream (Sparus aurata) fish with the task of removing inorganic nitrogen from the environment. According to the results, 153 m³ of Ulva tank surface area is required to completely remove the inorganic nitrogen produced by a 1 tonne school of sea bream.
 

Next station: inconspicuous species in the oceans

As we examine the benefits we derive from the sea, it may be time to shift our focus from the over-studied varieties. Focusing on species whose content has been extensively researched on many subjects can also create risks in ensuring the sustainable production of varieties of these species that are suitable for human consumption.

There are so many varieties that have their underwater potential to be unlocked, and it's exciting that researchers are moving away from the lure of these varieties that have been in focus many times before by the scientific community. What benefits will the oceans bring us that we do not know about?
 
We must first ask the right questions in the right place to find out the answers to these questions.