A blade of grass is considered the most inconsequential thing around us. Whenever we want to quote an example for drought-hit conditions, we say “not even a blade of grass will grow here!” What if this inconsequential living being becomes the most essential tool for fighting climate change?
What is Seagrass?
Seagrasses are marine flowering plants that grow in the coastal waters of every continent. Seagrasses, not to be confused with seaweed, grow in shallow coastal waters, providing a crucial nursery habitat for young fish of many species. They play a crucial role in coastal ecosystems by providing stability against erosion, and serving as vital habitats for diverse marine life, and mitigating climate change through carbon storage. Seagrass meadows are a vital habitat for marine life since they support biodiversity by providing essential nursery habitat for important fish species.
Rising importance of Seagrass
Scientists have found out that seagrass growing abundantly under the sea in coastal areas is the most suitable plant for absorbing carbon dioxide dissolved in seawater. It captures carbon up to 35 times faster than tropical rainforests, accounting for 10-18% of total ocean carbon storage despite covering less than 0.1% of the seafloor. Often called ‘nature’s water filter’, seagrass meadows help clean water by trapping carbon-rich sediments and absorbing nutrients and pathogens.
Monochromatic seagrass meadows may not be as colourful as coral reefs or as mysterious as mangrove forests. However, they are havens for fish, protect coasts from storms and are key stores of carbon, making them some of the world’s most valuable natural spaces. A 2020 report by UNEP found that seagrass meadows are nurseries for 20% of the world’s largest fisheries.
Despite their environmental, socio-economic and cultural values, seagrasses are undergoing accelerated rates of decline across the globe due to various threats including rising sea surface temperatures, extreme temperature events, coastal development, coastal urban and agricultural runoffs, and untreated sewage.
According to the IUCN, Seagrasses are being destroyed at 7% annually around the world, which is comparable to the decline seen in coral reefs and tropical rainforests. The decline in seagrass habitats has clear and detrimental ecological and socio-economic consequences.
Urgent need for seagrass restoration
Seagrass restoration is an essential aspect of mitigating climate change and supporting coastal environments and communities, especially given the increasing occurrence of extreme temperatures and storms that are expected to worsen seagrass decline.
The decline in seagrass habitats has major detrimental ecological and socio-economic consequences, and there is an urgent need to prevent this decline by facilitating recovery. Passive restoration efforts have reduced manmade hurdles to facilitate natural regeneration, such as the improvement of water quality by removing sewage flow and agricultural run-off.
Seagrass habitat restoration and meadow creation may include efforts such as the physical planting of seagrasses, distribution or planting of seagrass seeds, or coastal engineering to modify sediment and/or hydrodynamic regimes. Historically, seagrasses have shown a remarkable capacity to recover from large disturbances without any direct intervention. This is due to a combination of relatively well-connected seagrass populations and life history strategies of tropical species allowing for rapid colonization and growth. Listed below are some good case studies of seagrass restoration observed across the globe:
Case studies of seagrass restoration
Australia
Restoration research in Australia and New Zealand has focused on small-scale experimental tests using a variety of techniques ranging from the planting of sprigs (seagrass fragments) or plugs (seagrass cores) to seed-based restoration. The majority of seagrass restoration trials to date have used shoot-based techniques, with at least 46 studies since 1986. Although survival of transplanted seagrass fragments or cores was low in many studies, promising results are reported, with transplant units surviving more than 2 years or showing shoot densities similar to naturally occurring meadows.
Scientists at the University of Western Australia are currently developing an approach to collect, process, and remotely deliver seeds of Posidonia australis, and have seen some early successes at the trial stages. The use of seedlings in restoration is more well-established, especially in the use of hessian bags which act as a substrate.
America
Understanding the importance of seedlings in seagrass restoration efforts, the Indian River Lagoon National Estuary Program is building a seagrass nursery at Hubbs-SeaWorld Research Institute in Melbourne Beach. This seagrass nursery infrastructure includes continuous water flow, create a saltwater habitat extension using restoration materials like grasses and mangroves, along with an oyster breeding program.
Similarly, seagrass restoration projects in the Gulf of Mexico include transplanting seagrass into restoration sites, seeding seagrass, and modifying sediment to facilitate seagrass growth (usually used in combination with transplanting or seeding). Many seagrass restoration projects in the Gulf of Mexico, especially in Florida, are done to mitigate seagrass loss due to development, as required by the Clean Water Act. Some projects attempt to benefit seagrass by addressing water quality issues.
Indonesia
The Indonesian government has launched a climate mitigation plan focusing on the country’s seagrass meadows, an overlooked ecosystem that ranks among the most efficient carbon sinks on the planet. The country’s maritime sector also holds untapped potential as a vast carbon sink. The country is home to 11.5% of the world’s seagrass meadows, a position the government wants to leverage to increase its carbon storage options. Experts have calculated seagrass sequestration of carbon per given area to be 35 times greater than that of tropical rainforests.
India
Commercial seagrass farming in India is environmentally promising as well, since it tackles the root cause of climate change. According to the research by the Central Marine Fisheries Research Institute (CMFRI) led by P. Kaladharan, seagrass farming in India can largely aid in sequestering carbon dioxide and help combat ocean acidification. This project would provide direct livelihoods to 200,000 families in the country according to the Aquaculture Foundation of India.
