Due to its extraordinary inflexibility, rapid development, and resource sustainability, seaweed has become one of the most promising crops. It’s a significant development that will help unborn resources deplete.
With the increased position of the product and demand for seaweed encyclopedically over the years, algal coffers have reached a high stage of growth.
The product and processing of seaweed on a global scale during the past 20 years, as well as the most recent state of affairs and husbandry styles, are estimated.
Colourful seaweed operations’ product trends and exploration advancements are stressed. Also, the difficulties of seaweed farming and processing hassles are examined, and applicable results are suggested, offering guidance for both conditions.
With the ongoing growth and enhancement of applications in several industries, seaweed’s principal products, extraction and use, or waste utilisation, would provide larger benefits.
This blog post will explore the interesting field of seaweed farming, not leaving a stone unturned about its advantages, styles, and implicit environmental goods.
Read through this rich composition to learn why farming is a global phenomenon and causing a stir far and wide, whether you are an eco-enthusiast, an occupant of a littoral city, or you are just curious about sustainable practices.
Understanding Seaweed Farming:
What is Seaweed Farming?
The cultivation and harvesting of seaweed or algae is known as seaweed farming. Natural crops are managed by some seaweed farmers, while others have complete control over the whole growth cycle, from seed to harvest.
Seaweed is a kind of protist. Protists that resemble plants called seaweed have been grown and nurtured for generations in Asia. Seaweed farming has significantly increased worldwide in recent years as its popularity has grown.
According to a report by the Food and Agriculture Organization of the United Nations (FAO), global market production of seaweed increased from 10.6 million tonnes in 2000 to 32.4 million tonnes in 2018. In terms of production volume, farmed seaweed accounted for 97.1% of the total in 2018.
An estimate of the industry’s worth puts it at USD 6 billion. With a periodic product value in Japan of over USD 2 billion, nori is one of the most profitable monoculture species in the world.
With more than 1,800 species of green algae, 2,000 species of brown algae and well over 7,200 species of encyclopaedically flowering red algae, the algae family is incredibly diverse. It is estimated that there are between 200,000 and 800,000 different species of microalgae.
The most widely grown seaweeds are Eucheuma species and Kappaphycus Alvarez, which are grown for the natural gelling agent carrageenan; Gracilaria species are significant for agar; Saccharina species (kelp), Undaria pinnatifida (wakame), Pyropia species (nori), and Sargassum fusiforme (hiziki) are all grown.
In freshwater tanks, the microalgae Euglena and Chlorella are successfully farmed on a commercial scale in Japan and used for both nutritional and biofuel purposes.
Seaweed farming
China, Indonesia, and the Philippines are the top producers of seaweed. The nations of Korea, Japan, Malaysia, and Zanzibar are other important producers.
Depending on the type and environment where it is cultivated, there are several techniques to grow seaweed. It is frequently seeded onto thin ropes that are suspended in deep water using conventional mussel longlining techniques or, in shallow water, between bamboo poles. The majority of seaweed species use holdfasts, which are strong anchors, to fasten themselves to their expanding structure.
Seaweed grows without the need for additional inputs or food sources because it uses photosynthesis to turn sunlight into energy.
Growing seaweed has several intriguing advantages, including its capacity to capture carbon dioxide from the seas, which lowers atmospheric carbon and prevents ocean acidification. 53 billion tonnes of carbon dioxide could be taken out of the atmosphere annually if 9% of the ocean were used for seaweed cultivation. Additionally, seaweed takes up nitrogen from the water, which lessens ocean acidification.
The Importance of Seaweed for Marine Ecosystems
Seaweeds provide certain roles in marine ecology and are rudimentary factory organisms. Kelp timbers are made of large, thick seaweed, and they serve the opposite purpose as face timbers. Thousands of carnivorous species that inhabit aquatic settings rely on seaweed as their main food supply and bigger animals can also eat seaweed.
The position of seaweed in the marine food web is extreme. The sun provides the nourishment that seaweeds need to grow, and they also release oxygen via every part of their body. The most crucial task performed by seaweed is to balance nutrients and hazardous toxins that pose a threat to marine life by absorbing them. Seaweeds function as a sludge system in the enormous aquatic environment.
Chemicals and heavy essences are captured by them. They calculate iron for photosynthesis and reduce the amount of iron in the system as a result. For a very long period, the nearby organisms have been fed by seaweeds. They provide sustenance for living things as well. There is a wide range of animals and critters in the marine ecosystem.
They are given areas that are home to coral reefs, mangroves, and other aquatic life. The ocean’s inhabitants are in peril due to the ongoing dumping of rubbish into it. Seaweeds are the key to maintaining equilibrium and managing the most waste. Seaweeds may absorb heavy essences, which are harmful to the marine ecosystem. Because of the ecological importance of seaweed, its management must be sustainable.
Types of Seaweed Cultivated in Farms
Village-based, industrial-scale, or a combination of the two types of seaweed farming, along with the benefits and drawbacks of each
Techniques for Growing Seaweed
Apostille (post and line)
The standard method involves suspending several 10 m long lines between two posts, which are typically constructed of wood. This method works well for small-scale projects and lagoons since they have relatively shallow water at low tide.
The farmers may operate on foot during the two spring tide periods each month, making this a technique that is especially suited to women farmers. The lines are routinely checked and the seaweed is collected during these times. The seaweed is dried on land for a few days after each harvest before being sold.
Longlines
This method uses a rope up to 50 metres long, anchored at both ends and supported by floats spaced around every 10 metres. Farmers need access to a boat of some kind to access the plots because this technique is often used in water that is between 4 and 10 metres deep. However, because a boat is required, farmers may access the plots at all times, barring inclement weather.
Rock-based Spinosum Farming
Asia was the place where rock-based farming first appeared in the WIO region, in Zanzibar, as part of an EU-COI initiative. As the name implies, Spinosum cuttings are originally fixed by an elastic band to a rock (about the size of a huge fist), but after a few weeks, the seaweed establishes its fixation sites. Rocks should have a density of 25 per m2.
By merely cutting away the new growth each cycle and leaving enough of the “rootstock” for the cycle of development to start over again, this method allows the seaweed to be harvested at low tide and on foot.
This method saves a lot of effort since it eliminates the need to attach fresh cuttings after each harvest; for instance, a farmer employing line-based techniques would need to do up to 120,000 such harvest operations annually to maintain lines of just 3 km (= 15,000 separate plants). This method has clear advantages, and farmers in Zanzibar who used it described it as being similar to having a mango grove that produced fruit all year round.
The implementation of this technology is, however, severely limited by the need for a site that is well-protected from potentially choppy sea conditions. Certainly, the rocks in overexposed locations will eventually wash up on the shore or sink to the bottom of the lagoon.
Floating Rafts
This method is mostly used in Asia’s protected bays.
How Seaweed Farming Differs from Wild Harvesting
The Environmental Benefits of Seaweed Farming:
Carbon Sequestration and Climate Change Mitigation
Aquaculture of seaweed, which is the area of world food production that is expanding at the quickest rate, provides several options for climate change adaptation and mitigation. Seaweed farms emit carbon, which may be exported to the deep sea or buried in sediments, functioning as a CO2 sink.
The crop can also be utilised entirely or in part for the manufacture of biofuel, with a potential CO2 mitigation capacity of 1,500 tonnes CO2 km2 year 1 in terms of avoided emissions from fossil fuels.
By enhancing soil quality, replacing synthetic fertiliser, and lowering methane emissions from cattle when included in the feed, seaweed aquaculture can also aid in reducing emissions from agriculture. By lowering wave energy, defending shorelines, raising pH levels, adding oxygen to the water, and mitigating the local consequences of ocean acidification and deoxygenation, seaweed farming helps with climate change adaptation.
However, the potential for expanding seaweed aquaculture is constrained by issues such as the scarcity of appropriate places and rivalry for acceptable sites with other purposes, engineering systems capable of withstanding harsh offshore conditions, and rising market demand for seaweed products.
Despite these drawbacks, these farming techniques may be improved to maximise climatic advantages, which, if financially rewarded, may increase seaweed producers’ revenue.
According to the IPCC (2014), climate change adaptation is the process of adjusting to the present or anticipated climate and its impacts. In human systems, adaptation aims to mitigate or avoid harm or take advantage of advantageous chances, but in natural systems, it refers to human intervention to help the system adapt to the anticipated climate and its impacts.
We discuss seaweed aquaculture’s potential for preventing harm to sensitive ecosystems (like coastal protection and food security) and human systems (like providing refuge from ocean acidification and ocean deoxygenation) in this context.
Seaweed aquaculture may be able to contribute to some of the ecosystem services that kelp forests and macroalgal beds naturally sustain by establishing coastal habitats. As was already indicated, some of these functions help to reduce the effects of climate change, while others are useful for adapting to those effects.
For instance, farmed seaweed canopies reduce wave energy like that of wild seaweed canopies, acting as a living coastal protection structure that prevents erosion of the shoreline. Laminaria hyperborea-dominated kelp forests in Norway have been shown to lower wave heights by up to 60%.
The fact that farmed seaweed’s canopies are suspended from the surface rather than being benthic is a significant distinction in terms of the ability of farmed seaweed to minimise wave energy. The size and organisation of the seaweed habitat determine the wave-attenuating impact.
As was already indicated, some of these functions help to reduce the effects of climate change, and others are useful for adapting to those effects. For instance, the canopies of farmed seaweeds, similar to those of wild seaweeds, reduce wave energy and so act as living structures for coastal protection that serve as a barrier against coastal erosion. Wave heights are reduced by up to 60% in Laminaria hyperborea-dominated kelp forests in Norway.
The canopies of farmed seaweed are suspended from the surface rather than being benthic, which is a significant difference in terms of their ability to attenuate wave energy. Seaweed farms will be harmed by high-energy storms, therefore the wave-attenuating impact relies on the size and structure of the seaweed habitat.
When photosynthesis lowers CO2 concentrations throughout the day, dense seaweeds—both farmed and wild—represent production hotspots with accompanying high pH. As a result, they could help shield calcifies from anticipated ocean acidification. great daytime pH is likely a factor in the great biodiversity that kelp forests maintain, including calcifiers like lobsters, crabs, molluscs, and crustaceans. Similar reports of high biodiversity support seaweed farms have been made.
The potential for pH-upregulation and related impacts of seaweeds as refugia for calcifiers should grow with photoperiod as day periods of high production and pH in seaweed habitats might alternate with night periods when respiration causes lower pH. Seaweed productivity during midsummer near the poles when photoperiods surpass 21 h can provide persistent high pH during the summer period and be especially appropriate environments for calcifiers.
The ability of seaweed aquaculture to change pH and offer refuge for calcifiers also depends on flow regimes, and it is more effective when the farms are situated in coastal environments with weak currents or when the seaweed itself slows the flow. However, because this capability is lost after harvest, seaweed farms only temporarily have the ability to provide habitat for biodiversity.
Concern over the effects of climate change on the ocean, including ocean deoxygenation due to warming is growing, especially in eutrophic coastal regions that are more likely to experience hypoxia.
Because the seaweed is extracted rather than being remineralized in the environment and absorbing oxygen, seaweed aquaculture produces more autotrophic ecosystems than even those maintained by wild seaweed.
Therefore, seaweed farms offer environments that are high in oxygen, acting as refuges against hypoxia and falling oxygen levels, helping marine creatures adapt to this aspect of a warming ocean.
Planning in Space to Increase Seaweed Blue Carbon
For seaweed farming to have the greatest potential for reducing climate change, it is also essential that the farms have no adverse effects on the natural coastal carbon reserves, especially those linked to seagrass meadows.
As carbon sequestration hotspots, seagrass meadows are essential ecosystems for the Blue Carbon project. They are susceptible to mechanical damage and human interference that might result in shadowing from nearby seaweed farms’ operations. On the other hand, in extremely eutrophic environments, nitrogen removal by seaweed farms can enhance water quality and enable seagrass regrowth.
The location of seaweed farms must also take into account the habitat needs of the cultured seaweed and habitat conditions that maximise the crop’s quality for the intended application. Choosing locations rich in nutrients may have other environmental advantages, such as reducing the nutritional consequences of animal aquaculture when used in polycultures.
While eutrophic seaweed farming may boost the yield of some crops, it can be extremely difficult for other crops, such as kelp, which is susceptible to epiphyte overgrowth and therefore does better at less eutrophic sites with adequate water flow to replenish nutrients, CO2, and oxygen while restricting epiphytic growth.
A strategic move to maximise the benefits of seaweed aquaculture for climate change adaptation may be to locate seaweed farms in areas that are particularly at risk from the effects of climate change, such as low-lying coastal areas that are susceptible to flooding during storms with rising sea levels and areas susceptible to exposure to acidified and/or oxygen-depleted waters. But in addition to limiting the type of seaweed that may be produced, these and other environmental factors also limit the potential output of the farm.
Seaweed aquaculture spatial design for climate change mitigation should also aim to reduce life-cycle CO2 emissions by combining cultivation and processing, and where possible, meeting energy needs with renewable energy.
Additionally, spatial planning is necessary to reduce adverse interactions with other coastal activities including navigation and the environmental effects of seaweed aquaculture.
Nutrient Absorption and Water Quality Improvement
Seaweeds’ potential to improve global food security
Regarding its definition and policy applications, global food security is a dynamic operational concept that has been changing for decades. Food security is achieved when all people have equitable access to safe, sufficient, and nutritious food that can meet their particular dietary needs and preferences for an active and healthy lifestyle.
To maintain current consumption patterns by 2050, the world will need to produce 50% to 70% more food. Due to the ongoing rise in global population, it is essential to maintain sustainable food production, especially in terms of maintaining adequate quality and quantity to meet demand on a worldwide scale.
By increasing productivity per unit area, the present agricultural land must meet 90% of the world’s food supply demands, with the remaining 10% coming from the addition of new land. On the other side, increasing agricultural productivity is significantly hampered by the availability of water.
More than 70% of the freshwater that is accessible on Earth has already been used for irrigation. The quantity of additional water that may be used for agriculture is quite limited.
Intensive farming has had a large negative impact on the environment through overusing the world’s arable land, reducing the amount of freshwater available, accelerating climate change, and other factors. All of these variables might cause a movement in research towards the progress of underutilised crops and the creation of fresh, sustainable feedstocks.
One of the least used crops is seaweed, sometimes known as a marine vegetable. When produced and consumed by safety standards, they are nutrient-dense foods and can contribute significantly to global food security. The fact that seaweed agriculture may be developed and become self-sufficient in terms of the three main resources (land, freshwater, and fertiliser) is a crucial advantage.
If seaweed farming is increased in comparison to agriculture, significant water savings for food production may be achieved. Additionally, rivers and wastewater discharges, as well as epiphytes clinging to seaweeds, are a major source of nutrients for the world’s broad coastlines and marine regions. Seaweeds have a strong chance of becoming a vital addition to the worldwide veggie diet, improving the food supply chain.
A substantial and ongoing source of macro- and micronutrients for the human diet, the majority of seaweed species are edible. Consequently, seaweed farming has the potential to develop both as an agricultural addition and as an agricultural replacement.
It is conceivable that the expansion of seaweed farming on a global scale may help to replenish our existing food supply. With the added advantage of environmental services, it will also serve as a safeguard against agriculture’s possible incapacity to sufficiently handle the difficulties related to food security that we are now confronting.
Seaweed as a meal for human consumption
Despite being produced on a modest scale in the global food supply, several seaweed species are recognised as wholesome, tasty, and nutritious meals. Some of them are edible seaweeds, and Table 1 lists their direct dietary uses. They are primarily grown and consumed in Asia, where a variety of species have been used as traditional food sources for decades.
However, due to the growing popularity of Asian cuisine, they are also becoming more well-known and appreciated in Western nations. In addition to seaweed’s increasing popularity as a “sea vegetable” in the West, numerous and noteworthy claims for its nutritional and/or therapeutic benefits have been made in dietary literature. These seaweeds are eaten directly by residents of the Asia-Pacific islands as salad, snacks, desserts, and side dishes.
Additionally, they flavour soups, noodles, stews, garnishes, and drinks using these seaweeds. Fresh, dried, powdered, and flaked seaweed-based culinary items are available. Commercial seaweed-based meals such as burgers, drinks, sandwiches, ice cream, cake, chocolate, salad, chips, and biscuits are manufactured in addition to traditional seaweed-based items like Korean Wakame and Japanese Nori or Purple Laver.
Biodiversity Support and Habitat Creation
As the kelp aquaculture and afforestation industries continue to expand and develop internationally, the biodiversity advantages of these practices are receiving growing praise. However, it is still unknown if farmed kelp can offer this ecosystem function. Furthermore, there is a general lack of experimental studies on this topic.
According to the findings, it appears that kelp farms can produce habitat by altering the surrounding environment, notably by providing structure and altering the cycle of nutrients. It appears that kelp farms often establish unique habitats that sustain separate communities that are not similar to wild kelp forests, even though this can result in increased abundance and variety among some species (such as fouling organisms).
Furthermore, kelp farms’ ability to maintain biodiversity depends on a variety of operational aspects, some of which may conflict with agricultural goals that call for the elimination of the habitat such farms offer.
While additional research is needed to address the intricacy of kelp farm and forest comparisons, particularly at suitable experimental sizes, it presently appears unlikely that kelp farms would behave similarly to kelp forests and provide significant biodiversity effects. Instead, to achieve biodiversity goals, we should acknowledge farms for the unique services they provide and promote kelp forest restoration and conservation practices.
Demand for ecological sustainability and a greater understanding of the environmental advantages that the business might be able to offer have combined to bolster aquaculture’s global expansion. The capacity of some aquaculture operations to offer an ecologically sustainable product and supply ecosystem services will be an essential component of the industry’s future development given the need to prevent or eliminate negative environmental consequences.
This is especially true for seaweed aquaculture, which has seen a dramatic rise in popularity and scale recently. Encyclopedically, seaweed monoculture produces around 30 million tonnes of farmed seaweeds per time, with an estimated request value of US$13.7 billion( affectation- acclimated to 2022; FAO 2018). Since seaweed is an extractive crop that doesn’t require irrigation or fertilisers, the environmental implications of seaweed aquaculture are probably less severe than those of other forms of fertilised agriculture and fed aquaculture.
Additionally, farming has been promoted as a “magic bullet” remedy for issues including food security, coastal erosion, and climate change. These functions include carbon sequestration, nitrogen absorption, and habitat provisioning. As a result, there is now more attention being paid to afforestation techniques that attempt to cultivate seaweeds for “ecosystem regeneration” and biomass in hitherto untapped regions and conditions (such as kelp in the open ocean).
There is evidence that seaweed farms may provide a variety of important ecosystem functions, including the cycling and absorption of nutrients. However, it is still unknown or poorly understood how many other possible ecological services provided by seaweed farms work. One repercussion is that ‘hype’ may result in overpromising, which impedes research and industry growth and results in loss of social standing if expectations are not reached.
It is becoming clear that many of these ecosystem services are more complex to provide than is generally understood (for example, ecosystem exports/subsidies and biogeochemical processes affecting nutrient and carbon cycling and sequestration), and that there may be significant trade-offs to take into account.
Given these difficulties, one of the most urgent needs is an assessment of the advantages of kelp aquaculture and reforestation for biodiversity. Benefits from biodiversity can include increased species richness, abundance, biomass, and functional diversity (such as diversity in ecological function/role, morphology, and behavioural traits). The biodiversity advantages of natural kelp forests are unquestionably well known, and kelps serve as the trophic and physical underpinning for productive and biodiverse ecosystems by creating complex habitats.
Similar to its wild counterparts, farmed kelp may also provide habitat by offering structure, attachment places, and trophic subsidies that sustain populations of related creatures. If this is the case, kelp farms may offer comparable beneficial services that might aid in restoration, conservation, or socioeconomic results, much like it might be the case with some other types of aquaculture. Although there is growing acceptance that any biodiversity advantages from kelp farms may be minimal or highly variable, and difficult to accomplish in a commercial environment, there are still significant theoretical and practical concerns.
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