By Debasish Mahapatro
Hidden beneath tranquil coastal waters lies an ecosystem of immense value—seagrass meadows—quietly nurturing marine life, stabilizing shorelines, sustaining fisheries, and enhancing climate resilience, yet remaining largely unnoticed and undervalued.
There could be no better time than now to spark a global conversation on their significance, conservation, and future.
Seagrasses are unique and ecologically significant marine flowering plants that have fully adapted to life beneath the sea and preferably live in the bottom substratum. Unlike seaweeds, these are true angiosperms with roots, rhizomes, leaves, flowers, and seeds. They inhabit shallow coastal and estuarine waters worldwide, forming underwater meadows that rank among the most productive ecosystems on Earth after coral reef communities and mangrove ecosystems.
Ecologically, seagrasses function as foundation species and ecosystem engineers. Their extensive root-rhizome networks stabilize sediments, reduce turbidity, and prevent coastal erosion. Seagrass meadows also enhance nutrient cycling by trapping organic matter, facilitating microbial processes, and regulating nitrogen and phosphorus dynamics. They act as natural biofilters, improving water quality by absorbing excess nutrients and certain contaminants, thereby reducing the risk.
One of their most globally recognized roles is in blue carbon sequestration. Seagrasses capture atmospheric carbon dioxide through photosynthesis and store it both in plant biomass and in underlying sediments for centuries.
From a biodiversity perspective, seagrass beds provide essential nursery grounds for commercially important fish and shellfish species. Juvenile prawns, crabs, groupers, snappers, and molluscs depend on these habitats for shelter and feeding. They also support threatened megafauna such as dugongs and sea turtles, which directly graze on seagrass leaves. Migratory birds use shallow seagrass zones as feeding grounds while fish and shellfishes use it for breeding and nursery grounds, especially in lagoon systems. The structural complexity of seagrass canopies increases habitat heterogeneity, promoting higher species richness compared to adjacent bare substrates.
In India, seagrasses occur along both the east and west coasts, including lagoons, coral reefs, and island systems. Approximately sixteen species across seven genera have been documented nationally. Significant diversity is found in the Andaman and Nicobar Islands, Lakshadweep, the Gulf of Mannar, Palk Bay, and the Gulf of Kutch.
On the east coast, Chilika Lagoon stands out as one of the most important seagrass habitats. This lagoon supports a diverse assemblage of seagrass species from the saline waters of the lagoon such as Halophila ovalis, Halophila ovata, Halophila beccarii, Halodule pinnifolia, Halodule uninervis, and Ruppia maritima. Among them, Halophila ovalis and Halodule uninervis are widely distributed and form extensive meadows. Areas such as Rambha Bay, Nalabana Island, Arakhkuda, and Magarmukh are particularly known for rich seagrass meadows and associated faunal diversity found in patches in shallow areas.
Similarly, the Haripur Creek near Gopalpur along the southern Odisha coast harbors seagrass patches dominated by Halophila and Halodule species. Recently, creek seagrass patches reappeared during the Covid pandemic. However, both Chilika Lagoon and Haripur Creek seagrass ecosystems face pressures from anthropogenic sources and natural climatic extremes.
Recognizing their global importance, the United Nations General Assembly adopted Resolution A/RES/76/265 in May 2022, officially designating 1 March as World Seagrass Day. This observance highlights the urgent need to raise awareness and promote coordinated action for conservation and restoration. Seagrasses contribute directly or indirectly to numerous Sustainable Development Goals (SDGs), including those related to climate action, life below water, food security, and sustainable communities. Incorporating seagrass ecosystems into the blue economy framework seems vital.
The decline of seagrasses carries profound socioeconomic consequences. Coastal communities dependent on small-scale fisheries rely heavily on the productivity of seagrass ecosystems. Habitat degradation can diminish fish stocks, threaten food security, and weaken traditional livelihoods. Their loss increases vulnerability to erosion, flooding, and extreme weather events, particularly in low-lying regions already at risk from sea-level rise.
Therefore, conservation and restoration of seagrass ecosystems are strategic investments rather than purely environmental actions. Artificial transplantation, habitat restoration, and water quality management can accelerate recovery where natural regeneration is slow. Awareness campaigns, school outreach, and citizen science initiatives can further strengthen public understanding of seagrass benefits.
The writer is a marine biologist. Views are personal