Date : 28/07/2023

Relevance: GS Paper 3; Environment conservation

Keywords: Blue Carbon, The lungs of the sea, Carbon Sequestration, Nutrient Recycling

Context-

Seagrass meadows, located off the coast of Kiel in northern Germany, are under threat due to worsening water quality. However, a pioneering initiative called the SeaStore Seagrass Restoration Project, led by the GEOMAR Helmholtz Centre for Ocean Research, is empowering citizen divers to restore these crucial ecosystems.

Seagrasses as Ecosystem Engineers:

• Maintaining Water Quality: Seagrasses play a crucial role in maintaining water quality by trapping fine sediments and suspended particles in the water column, which leads to increased water clarity. This natural filtration process prevents sediments from being stirred by wind and waves, benefiting marine animal behavior and the recreational quality of coastal zones.
• Nutrient Filtering: Seagrasses act as nutrient filters, intercepting and filtering nutrients released from land-based industries before they reach sensitive habitats like coral reefs. This role is vital in preserving the health and balance of marine ecosystems.
• Stabilizing the Sea Bottom: The extensive vertical and horizontal root systems of seagrasses function like those of land grasses, effectively stabilizing the sea bottom. In areas lacking seagrass communities, the ocean bottoms are more susceptible to intense wave action from currents and storms.
• Providing Food and Habitat: Seagrasses serve as essential sources of food and habitat for a wide range of marine species, including fishes, octopuses, shrimp, blue crabs, oysters, sponges, sea urchins, and clams. Their presence supports diverse marine life, making them vital components of marine ecosystems.
• Oxygen Release: Known as "the lungs of the sea," seagrasses release oxygen into the water through photosynthesis. This oxygen production benefits marine organisms and contributes to the overall health of coastal waters.
• Protection for Juvenile Marine Life: Seagrass habitats offer protection for juvenile and small adult fish from large predators and strong currents. Marine animals living in soft sea bottom sediments also find shelter in seagrass meadows, while seagrass leaves provide anchoring facilities for seaweeds.
• Nutrient Recycling: After decomposition, seagrasses release nutrients such as nitrogen and phosphorus back into the water, where they are absorbed by seagrasses and phytoplankton, sustaining the marine food chain.
• Carbon Sequestration: Despite occupying only 0.1% of the ocean floor, seagrasses are remarkable carbon sequesters, burying up to 11% of the organic carbon in the ocean. Annually, they absorb 83 million tonnes of carbon from the atmosphere, capturing carbon up to 35 times faster than tropical rainforests.

Seagrasses, as ecosystem engineers, play a pivotal role in maintaining marine biodiversity, improving water quality, and contributing to carbon sequestration. Their intricate root systems stabilize the sea bottom, providing essential habitat and food sources for numerous marine species. As endangered marine organisms directly rely on seagrass leaves for sustenance, preserving these underwater meadows is critical for the health and balance of marine ecosystems.

Threats to seagrasses:

• Seagrass beds are facing a decline all over the world at the rate of 2-5 percent annually.
• Some 30,000 square kilometers of seagrass have been lost during recent decades at a global level.
• Seagrasses face natural disturbances like grazing, storms, ice-scouring, and desiccation.
• Human disturbances like eutrophication, mechanical destruction of habitat, overfishing, and release of nutrients play havoc on seagrasses. Siltation, trawling, coastal engineering construction, pollution, etc, are considered to be significant causes of the deterioration of seagrasses.
• Another major cause of seagrass disappearance is coastal eutrophication. Rapidly developing human population density along coastlines has led to high nutrient loads in coastal waters from sewage and other impacts of development. Increased nutrient loads create an accelerating cascade of direct and indirect effects that lead to seagrass decline. While some exposure to high concentrations of nutrients, especially nitrogen, and phosphorus, can result in increased seagrass productivity, high nutrient levels can also stimulate the rapid overgrowth of macroalgae and epiphytes in shallow water and phytoplankton in deeper water. In response to high nutrient levels, macroalgae form dense canopies on the surface of the water, limiting the light able to reach the benthic seagrasses. Algal blooms caused by eutrophication also lead to hypoxic conditions, which seagrasses are also highly susceptible to.
• Seagrasses are also negatively affected by changing global climatic conditions. Increased weather events, sea level rise, and higher temperatures as a result of global warming all have the potential to induce widespread seagrass loss. An additional threat to seagrass beds is the introduction of non-native species. For seagrass beds worldwide, at least 28 non-native species have become established. Of these invasive species, the majority (64%) have been documented to infer negative effects on the ecosystem.

Initiatives for restoring seagrasses

• The SeaStore Seagrass Restoration Project: The SeaStore Seagrass Restoration Project is a significant initiative undertaken by the GEOMAR Helmholtz Centre for Ocean Research to restore seagrass meadows in the Baltic Sea. Citizen divers are trained to perform the restoration autonomously, making it one of the first projects of its kind. The decline of seagrass meadows in the Baltic Sea and across Europe has led to the release of carbon into the atmosphere, accelerating global warming. Through the SeaStore project, restored seagrass meadows can become significant carbon storage sites, potentially sequestering millions of tonnes of CO2.
• Excellent ‘blue carbon’ sinks project proved the potential of seagrass meadows for carbon sequestration, a role also stressed in the Paris climate agreement of 2015.

• Abu Dhabi Marine Restoration: Focuses on restoring seagrass beds, coral reefs, and mangroves in the UAE, with 7,500 hectares restored and another 4,500 hectares targeted by 2030.
• Small Island Developing States Restoration Drive: Targets restoration in Vanuatu, St. Lucia, and Comoros to reduce pressures on coral reefs and promote sustainable island development.
• Building with Nature in Indonesia: Innovative coastal restoration in Demak, Indonesia, through natural structures, benefiting mangroves, shrimp production, and fisheries.
• The new Guidelines on Seagrass Ecosystem Restoration (SER) are intended to serve as a tool in support of seagrass restoration opportunities in the Western Indian Ocean initiated by UNEP. Recently restoration was initiated in the Gulf of Mannar.

Conclusion:

Seagrasses, as ecosystem engineers, play a pivotal role in maintaining marine biodiversity, improving water quality, and contributing to carbon sequestration. Their intricate root systems stabilize the sea bottom, providing essential habitat and food sources for numerous marine species. As endangered marine organisms directly rely on seagrass leaves for sustenance, preserving these underwater meadows is critical for the health and balance of marine ecosystems.

Source : The Indian Express