24 Oct

Seagrass

< General Studies Home Page 

Contents

• Introduction
• The Major seagrass ecosystem along the coast of India 
• Significance of Seagrasses Ecosystem
• Threats to seagrass ecosystem

---

Introduction

• Seagrasses are marine flowering plants that thrive fully submerged in shallow oceanic and estuarine habitats. They are one of the most important coastal habitat.
• Global coverage of seagrass is estimated to be 3.45 X 10^5 km2, which represent about 0.1% – 0.2% of the ocean floor.
• In India, total seagrass cover is estimated to be 517 km2 with 14 reported species and six genera.
  • Halophila beccarii (IUCN: VU), is the most commonly distributed species reported from all the coastal states except islands, acts as a pioneer species in the succession process of mangrove formation.
• Distribution of seagrasses in India:
  • The overall distribution of seagrass meadows in India occurs from the intertidal zone to a maximum depth of 15 m with varying species diversity.

The Major seagrass ecosystem along the coast of India are found in:

1. Gulf of Mannar and Palk Bay regions on the east coast comprise the largest seagrass meadows in India, covering 80 and 320 km2 respectively.
2. The Ramasar site of Chilika Lagoon in Odisha state also has seagrass meadows that have expanded from 20 km2 to 80 km2 after the opening of the new bar mouth.
3. Gulf of Kuchchh on the west coast;
4. The lagoons of islands in the Lakshadweep in the Arabian Sea and;
5. Andaman and Nicobar Islands in Bay of Bengal. 

Significance of Seagrasses Ecosystem:

• Provisioning Services:
  
  

                                Seagrass Ecosystem Services

  • Medicine (treatment of heart conditions, sea sickness etc.)
  • Food (Nutritious seeds)
    • Recently, a study has shown the presence of various biological metabolites in some India seagrass that can be used effectively in the food and pharmacological industries.
  • Fertilizer (Nutrient rich biomass)
  • Livestock feed (food for goats sheep etc.)
  • Building Material (Such as roofing for houses)
• Supporting Services:
  • Key Fishing Grounds as they offer a complex habitat for a variety of fish and other marine organisms like Dugongs.
    • Seagrass based fisheries are globally important and are present wherever
      seagrass exists, supporting subsistence, commercial and recreational activities.
    • Their high rates of primary production result in well-oxygenated waters that support complex food webs.
• Regulating Services:
  • Coastal Protection: Seagrass reduce the energy of waves and thus protect the
    seashore.
  • Carbon Sequestration: Seagrass store more than twice as much carbon from planet warming CO2 per square mile than forests do on land, according to a 2012 study. They accumulate CO2 from both in-situ production and sedimentation of particulate carbon from the water column.
  • Water Purification: They trap fine sediments and suspended particles in the water column and increase water clarity.

Threats to Seagrass Ecosystems

Globally, seagrass habitations have declined in area and several species are threatened due to several natural and anthropogenic stressors:

• Natural Stressor: Cyclones, heavy rainfall, coastal uplift and subsidence, grazing herbivores, and diseases
• Anthropogenic Stressors:
  i. Commercial Fishing and trawling activities: this is the most important threat to seagrass in India.
  ii. Boat activities for recreational purposes
  iii. Runoff (Pollution) from coastal aquaculture and agriculture
  iv. Shell Harvesting and Seaweed cultivation
  v. Accidents like Oil Spills.

Key Steps which protect Seagrasses:

• CRZ Notification 2011, issued under Environmental (Protection) Act, 1986, has classified seagrass meadows as CRZ1-A (Ecologically sensitive area). It prohibits developmental activities in its vicinity.

Way Forward:

• Mapping of existing seagrass areas and areas with potential of growth of seagrass.
  • Here steps can be taken for natural expansion of seagrass.
• Effective implementation of available legislation may help reduce the threats.
  • Ensuring that the provisions of protection accorded to CRZ-1 are strictly followed can prevent degradation and can lead to self-restoration of seagrass meadows.
• More study on the various uses of seagrass by local communities and then spreading awareness among all the stakeholders about the various ecosystem services provided by the seagrasses, especially their role in carbon sequestration.
• More R&D on the various applications of seagrass by local communities
• Research is also needed on the techniques for seagrass transplantation to increase the coverage of seagrass.
  • Learn from Seastore Seagrass Restoration Project on how to train local population to autonomously transplant and increase seagrass cover.
• Increased collaboration between various stakeholders – Government, researchers, local communities etc to develop an action plan for seagrass conservation.