Seaweed Culture – An Adaptation cum Mitigation Response to Climate Change in India

By Nuzhath Khanam

In 2019, the Centre published the Revised Draft Mariculture Policy, to enable sustainable development of mariculture in India in order to reach its potential of 4 to 8 million tonnes from its current levels of 0.01 million tonnes and seeks to promote farming of seaweeds for extraction. It also recognizes the role of seaweed culture in ensuring nutritional security and improving the livelihood of coastal communities. Recently, National Fisheries Policy, 2020 also recognizes mariculture as an alternate livelihood option, reducing the stress on fisheries, and envisages the expansion of seaweed culture. Why is this relevant in climate change? A Special Report of the Intergovernmental Panel on Climate Change (2019) suggests to promote further research attention on seaweed aquaculture, considering its increased potential to achieve negative carbon emissions. Recently, a study led by Indian Council of Agricultural Research-Central Marine Fisheries Institute (ICAR-CMFRI), has concluded that seaweeds play a role in combating higher levels of CO2 and therefore can be effective in mitigating effects of ocean acidification. India has an approximate record of 865 species of seaweeds along its coasts, with the highest diversity and abundance in coasts of Tamil Nadu and Gujarat.

Along the Gulf of Mannar (Coromandel Coast), the commercial cultivation of seaweed through the collaboration of Central Salt Marine Chemical Research Institute and Central Marine Fisheries Research Institute has not just given an alternate livelihood option, but has also empowered women resulting in burgeoning number of women led self-help groups. Another study based in Ramanathapuram and Mandapam areas of Tamil Nadu, found that a substantial portion of seaweed farming families were women-led which further motivated others to engage in seaweed farming, thereby emerging as a sustainable livelihood option with a potential to relieve pressure on fisheries. Similar effects of seaweed farming on women empowerment and positive environmental impacts in countries like Philippines, Tanzania and Indonesia has also been highlighted by the Food and Agricultural Organization while assessing its technical and economic importance.  Further, with an increasing demand, cultivation of seaweed is thus seen as a potential area for revenue development for coastal communities in developing nations

Seaweed Culture – An emerging Blue Carbon Sequester with Multiple Co-Benefits

Blue carbon is defined by the IPCC as carbon captured by living organisms in coastal and marine ecosystems. International Union for Conservation of Nature (IUCN) recognizes blue carbon as “nature-based” solution to climate change with multiple co-benefits such as carbon sequestration in terms of mitigation and coastal protection from wave energy, sea level rise, spawning grounds for fish etc., in terms of adaptation. However, unlike mangroves, tidal marshes and seagrasses(1), macro algae (seaweeds) are not mostly included in blue carbon assessments due to associated uncertainties. The contribution of seaweeds in climate change mitigation strategies as “carbon sinks” is recently being reconsidered which is also evident in the previously stated IPCC Special Report. In India, an experimental study (2009) revealed that a total of 260876 tonnes of seaweed biomass along the Indian coast, absorbed 9052 tCo2/day while emitting 365 tCo2/day. It is also noteworthy that, of the 3 types of algae studied, the emission is attributed to one specific type, with the other two species quantifying zero Co2 emissions. An Australian study establishes that macro algae (seaweeds) have a limited capacity for carbon sequestration, since they are unable to accumulate carbon underground due to their lack of roots, but nevertheless abundantly contribute to carbon sequestration by acting as “carbon donors”, donating carbon to another habitat which buries the carbon.  

It is high time to integrate climate change mitigation and adaptation approaches into other policies to “simultaneously advance economic and environmental objectives”

From Adaptation to Mitigation cum Adaptive Response

An Inventory of Blue Carbon related Nationally Determined Contributions (NDC’s) published by the IUCN, classifies the respective mitigation and adaptation actions as identified in the countries’ NDC’s. India’s NDC, without mentioning “blue carbon”, takes only adaptation approach for conservation and management of coastal zones for climate change through mangroves and other coastal ecosystem. It has not specifically recognized both adaptation and mitigation (mitigation co-benefits).  The table based on Duarte et al. lists down the climate change adaptation and mitigation potential of seaweeds:



1. Avoids deoxygenation of coastal ecosystem by warming.

2. Dissipates wind energy and protects the coastline

3. Combats ocean acidification impacts by absorbing Co2.

4. Provides alternative livelihood for fishing communities.


1. Biological charcoal (Biochar)

2. Bio-fuel (Indian company based in Bangalore currently focusses on bio-fuel potential of seaweeds)

3. Additive in Cattle Diet reduces methane emission in dung(2). Its potential is especially relevant in India, which has a gap between cattle production and beef consumption, resulting in more methane emission during its lifetime.

The mitigation cum adaptation potential of seaweeds remain far from utilization. Even at the international arena, the potential of seaweed in the context of climate change was recognized, only very recently by the IUCN. Subsequently, the International Blue Carbon Initiative coordinated by the Conservation International (CI), the International Union for Conservation of Nature (IUCN), and the Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific, and Cultural Organization (IOC-UNESCO), which has so far focused on mangroves, tidal marshes and seagrasses has discussed the potential of seaweeds and resolved to address the differences in literature with regard to potential of seaweed aquaculture in climate change mitigation. With such an international progress and indigenous research indicating the carbon sequestration potential of seaweeds, seaweed aquaculture can be developed with cross-cutting policies that combat climate change, rather than taking an isolated approach for extraction through culture. It is high time to integrate climate change mitigation and adaptation approaches into other policies to “simultaneously advance economic and environmental objectives” as envisioned in the National Action Plan on Climate Change.


 (1) Seaweeds are different from seagrasses. Seaweeds are macroalgae lacking roots, whereas seagrasses are rooted plants. See for more information on differences between seagrass and seaweeds.

(2) See Breanna M. Roque et al., Inclusion of Asparagopsis armata in lactating dairy cows’ diet reduces enteric methane emission by over 50 percent, 234 Journal of Cleaner Production (10 October 2019).



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Nuzhath is a student of TNNLU pursuing her B.A.LL.B. (Hons.). An avid reader with a strong sense of social justice, she is fondly called as “Pen Bharathi” (Female Bharathi) by her few friends. She likes being simple, but it doesn’t reflect in her works. People are rest assured that a job would be done when she’s on board, and nothing more than a roadside coffee on a rainy day satisfies her. As a friend, you can trust her with your feelings and she can lend her ears all day, but her bestie ruins it by pestering her to complete her assignments.

She has a love for environment, travelling to historical venues and having a chat with the local people. But she doesn’t like boasting about herself. That’s why she outsourced this bio-writing to her bestie. She is a great friend to be with, and an even interesting person to engage in conversations. Just that her schedule keeps her too busy.

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