Seaweed cultivation boosts Sri Lanka’s ‘blue economy’ ambitions


  • Seaweed cultivation is an increasingly important part of the global food system and offers a range of benefits, including sustainable coastal livelihoods and economic diversification, food production, export earnings, mitigation and adaptation to climate change, pollution control and organic fertilizers.
  • Sri Lanka had a significant seaweed market in the 1930s, but today there is only limited and small-scale seaweed farming in the country, mostly without processing or adding value. .
  • With greater investments in money, technology and know-how, Sri Lanka could offer the perfect place to grow seaweed either alone or in integrated mariculture, for example with shrimps, molluscs or sea cucumbers, according to experts.
  • Cultivation of seaweed in Sri Lanka could be a viable and highly beneficial part of expanding the blue economy if the initial challenges are overcome and the coastal communities engaged with the support, guidance, technology and control of the quality, according to experts.

COLOMBO – Within its territorial waters and exclusive economic zone, Sri Lanka is home to an abundance of coastal and marine resources. And while national policies and development visions already target a blue economy, much of this natural wealth is currently not being used sustainably or to its full potential, experts say.

“Coastal fishing communities are vulnerable,” says Ruchira Cumaranatunga, senior professor in the Department of Fisheries and Aquaculture at the University of Ruhuna. “There is a need to create or improve alternative livelihoods in the coastal areas of Sri Lanka. While helping inshore fishermen to maintain their fishing activities, they should be provided with additional sources of income. The best method for this would be to promote small and medium enterprises based on fish processing, use of fishery waste or fish waste and seaweed cultivation. Women and school dropouts from fishing families could be involved in these SMEs.

Algae could help diversify the livelihoods of coastal fishing communities in Sri Lanka. Image courtesy of Ashan Karunananda.

The benefits of algae

Cultivation of seaweed in particular offers a way to develop the blue economy and create sustainable livelihoods, according to supporters. Globally, algae aquaculture is one of the fastest growing components of food production, with 99% of production taking place in Asia. If the sector grows further, it could generate 500 million metric tonnes dry weight by 2050 and completely replace fishmeal and fish oil in animal feed, provide protein to humans and save vast amounts of land and freshwater. There are many other ways that algae benefit humans, the environment and the climate.

Commercial value types of algae are algae species that generally fall into three groups: green algae (Chlorophyta spp.), red algae (Rhodophytes spp,) and brown algae (Pheophyte spp.). The different species of algae have many uses and their cultivation has a small environmental footprint, as they do not significantly alter the existing coastal environment or require the input of fertilizers, freshwater resources or water. medications.

“Algae species like Ulva lactuca [sea lettuce], Caulerpa racemosa, Where Caulerpa lentillifera [sea grapes] are popular specialties, ”says Isuru U. Kariyawasam, senior lecturer in the botany department at Sri Jayewardenepura University. “In addition, the chemicals extracted from algae can be widely used as nutraceuticals, pharmaceuticals, UV blockers, anticancer compounds, and many other applications.”

Dilanthi Koralagama, a senior lecturer at Ruhuna University, says growing algae could also provide inputs for the organic fertilizer industry. “As some algae and microalgae contain relatively high percentages of nitrogen,” she says, “the problems with the nitrogen content in organic manure can be solved to a certain extent, which is not possible. using only terrestrial flora and fodder “.

Seaweed drying on the shore of Kalpitiya in northwest Sri Lanka. Image courtesy of Dilanthi Koralagama.

Algae can be grown quickly and vertically, making efficient use of the available aquatic space and providing an opportunity to diversify the coastal blue economy. However, providing a sustainable source of income and employment for coastal communities is just one of the many benefits and opportunities that algae could offer.

“Growing algae can provide alternative livelihoods,” says Sarath Jayanatha, research fellow at the National Aquatic Resources Research and Development Agency (NARA). “Income generation is a major product of algae cultivation, but if it can be initiated on a larger scale, algae could also be important in mitigating climate change. “

Algae are very versatile and useful when it comes to tackling the causes and impacts of climate change. On the one hand, algae store carbon dioxide and can be used to produce biofuels, replace inorganic fertilizers, or reduce methane emissions for livestock feed. On the other hand, algae are an effective adaptation tool that can reduce wave energy and protect shorelines, improve water quality and mitigate the local effects of ocean acidification and loss of water. ‘oxygen.

In addition, algae can be used to clean up pollution in the marine and coastal environment by removing pollution from agricultural nutrients. Such pollution is difficult to remove once it enters the water, and algae is one of the few effective methods of dealing with it.

Algae are versatile and have many different uses and benefits, including the production of food and fodder, the production of fertilizers or chemicals. Image courtesy of Isuru U. Kariyawasam.

Seaweed cultivation in Sri Lanka

“Currently, seaweed cultivation is only practiced on a small scale in Sri Lanka,” explains Cumaranatunga. “The seaweed is dried and exported without any added value. Sri Lanka has a lot of living and non-living resources in the coastal belt, but at the moment they are mined and sold to other countries. The added value in Sri Lanka could be an extremely important topic.

Sri Lanka’s coastline is teeming with algae species and habitats, for example along the southwest coast from Ambalangoda to Galle, or along the northern coast near Jaffna, the Palk Strait and the Gulf of Mannar.

“Growing or cultivating seaweed is an inexpensive, low-tech practice that requires few inputs and has been practiced in many Asian countries for decades or centuries,” says Kariyawasam. “However, in Sri Lanka it is still in its infancy. We have many sheltered bays, lagoons and estuaries that could be used, but so far no large-scale attempts have been made to establish seaweed mariculture in the country.

If such large-scale attempts were undertaken and algae cultivation improved alongside the coastal sector and its blue economy, Kariyawasam says, it would open up a future of many possibilities: “Integrated multitrophic mariculture systems (IMM) are a very efficient and sustainable method for growing algae. The algae could be grown in polycultures with shrimp and molluscs and even help solve the problems of aquatic pollution and effluent treatment from existing shrimp farms. Seaweed mariculture could also be integrated with sea cucumber culture to open up new avenues towards sustainable mariculture systems.

Koralagama highlights the economic potential: “Some species of algae provide edible protein and are recommended as a dietary supplement. Growing these seaweed for export could bring foreign currency to the country, as there is already a well-established market in developing countries.

Cultivation of seaweed could help diversify the livelihoods of coastal fishing communities in Sri Lanka. Image courtesy of Ashan Karunananda.

Challenges and prospects for Sri Lanka

Considering all these benefits and applications, what is the potential of seaweed cultivation in Sri Lanka? If it is indeed a viable source of livelihood that offers a range of co-benefits, why has it not yet been adopted on a larger scale?

NARA’s Jayanatha says many companies are trying to get grants through algae projects. “As a result, many of these companies are unwilling to invest their own money,” he adds.

“It is important to note that the cultivation of algae requires sufficient capital and appropriate technical know-how to be set up,” explains Koralagama. “Therefore, support from the private sector is essential to develop the seaweed industry in Sri Lanka. “

Even with financial support, however, there are still hurdles and challenges to overcome, Kariyawasam said. “Some of the constraints to building a strong seaweed industry in Sri Lanka are lack of awareness and knowledge, lack of dissemination of technology, lack of seed stocks, personal attitudes and lack of motivation of fishing communities. , environmental fluctuations and short, seasonal life cycles. of certain species of algae. Sri Lanka had a strong seaweed market in the 1930s, but it has been lost due to the adulterations by our people. Therefore, it is very important to build high quality stocks for export when improving the seaweed industry in Sri Lanka. “

The possibility of expanding algae aquaculture is also limited by the availability of suitable areas, the competition for these areas with other uses, the availability of engineered systems capable of coping with rough sea conditions and the market demand for seaweed products.

As the world increasingly realizes the potential of a sustainable blue economy, investing in seaweed could have many benefits for Sri Lanka, experts say. In addition to providing a relatively inexpensive, low-tech option for the economic diversification of coastal communities, they point out, algae cultivation also offers a range of use cases as well as serious mitigation co-benefits. climate change, resilience, environmental protection, and pollution control.

Banner image of seaweed on the beach near Mannar in northern Sri Lanka, courtesy of Dilanthi Koralagama.

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