Joint study on Seaweed Cultivation, Potential and Ecological Safeguards in the Gulf of Mannar, Tamil Nadu

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The Project

Farming of seaweeds is a relatively robust form of aquaculture. World production has been characterized by exponential growth during the last 50 years and more than tripled between 2000 and 2018, from 10.6 million tons to 32.4 million tons (Mt) (FAO, 2020). While seaweed farming is expanding rapidly in a few countries and slowly gaining acceptance in others, it is still far from becoming a common practice in most of the ~150 countries and territories of the world endowed with coasts. However, the already significant increase in the production of and demand for farmed seaweeds is indicative of their potential as a significant complement to agricultural crops. Besides extensive coastal areas, vast expanses of sea might be turned into ecofriendly cultivated fields.

India’s Blue Economy can be defined as a subset of the national economy comprising of the entire system of ocean resources and man-made economic infrastructure in marine, maritime and the onshore coastal zones within India’s legal jurisdiction, which aid in the production of goods and services and have clear linkages with economic growth, environmental sustainability and national security. The Central Government is encouraging coastal states to take up seaweed farming under the Pradhan Mantri Matsya Sampada Yojana (PMMSY) which places thrust on it as a means of job creation. In the 2021-22 budget, Union Finance Minister has announced a Multipurpose Seaweed Park in Tamil Nadu and considering seaweed farming “an emerging sector with potential to transform the lives of coastal communities” and the study is to be conducted by NCSCM, MoEF&CC, CSIR-CSMCRI and ICAR-CMFRI.

Seaweed cultivation potential and ecological safeguards


The study would be undertaken to understand the exact impact of seaweed cultivation on corals and seagrass by collecting the data for 5 cycles in the coast of Tamil Nadu, around Gulf of Mannar and Palk Bay in a span of one year


  • Environmental Monitoring

    • Identify the drivers of environmental change due to seaweed farming
    • Assessment of water quality (detailed list of parameters given below) from proposed six seaweed culture sites to evaluate baseline conditions, during culture and post-harvest at Gulf of Mannar and compare with the existing culture sites at Palk Bay
    • Undertake hydrodynamic surveys to determine waves, tides and currents at the farming sites and adjacent coastal waters
    • Determine organic carbon and nitrogen concentration in the surface sediments and particulates- from the culture sites and in the adjacent ecologically sensitive areas
    • Assessment of Plastic debris (including microplastics)
  • Ecological Monitoring

    • Assess primary productivity and plankton (photo and zoo) community structure during and post seaweed cultivation in the experimental farms at Gulf of Mannar and in existing farms at Palk Bay in comparison to baselines prior to commencement of farming
    • Assessment of fish diversity, meiobenthic, benthic population epiphytes and epizooites at the experimental farming sites at Gulf of Mannar and in the existing farms at Palk Bay
    • Seaweed-Microbial interactions and key functions of seaweed-associated bacterial communities
  • Impact Assessment

    • Hydrodynamic modelling of waves, tides and currents to determine the flow conditions to the seaweed farm and the connected habitats
    • Determine impacts (both positive and negative) on ecologically sensitive areas such as coral reefs and seagrass ecosystems by assessing the coral health index and sea life index in systems adjacent to the seaweed farming sites
    • Evaluation of impacts (if any) on coral and seagrass health and herbivore fish population
    • Evaluation of the impact of seaweed farming on the fish diversity, meiobenthic, benthic population, epiphytes and epizooites
  • Impact Assessment

    • Preparation of guidelines for environmental and ecological safeguards.

Expected Outcomes

  • The culture potential in Gulf of Mannar for undertaking large-scale commercial cultivation of alvarezii
  • Differences in growth performance of alvarezii between Gulf of Mannar (at the proposed sites)