About
Seagrasses are marine flowering plants that are found in shallow waters in many parts of the world, from the tropics to the Arctic circle. They exist in 159 countries on six continents, covering over 300,000 km2, making them one of the most widespread coastal habitats on Earth. Seagrasses form extensive underwater meadows, creating complex, highly productive and biologically rich habitats. Seagrasses also play a significant role in providing a plethora of highly valuable ecosystem services that greatly contribute to the health of the world’s ecosystems, human well-being and the security of coastal communities (UNEP, 2020).
Take a journey through our interactive series to dive into how humanity can safeguard and restore underwater habitats.
Ecological Status and Trends
Seagrasses cover only 0.1 per cent of the ocean floor but provide shelter and food for thousands of species, including fish, shellfish and threatened, endangered and charismatic species, such as dugongs, seahorses and sea turtles.
However, seagrasses have been declining globally since the 1930s, with the most recent census estimating that 7 per cent of this key marine habitat is being lost worldwide per year, which is equivalent to a football field of seagrass lost every 30 minutes. They are one of the least protected coastal ecosystems in the world.
Threats with the highest impact to seagrasses include agricultural and industrial run-off, coastal development and climate change. Unregulated fishing activities, anchoring, trampling and dredging also pose major threats. However, despite a general global trend of seagrass loss, there is reason for hope, as some areas have shown abating declines or substantial recovery of seagrasses. These recoveries can often be attributed to human interventions reducing the effect of human-caused stressors.
Why Does it Matter?
Seagrass meadows are of fundamental importance to world fisheries production, providing valuable nursery habitat to over one fifth of the world’s largest 25 fisheries. Seagrasses can also improve water quality by filtering, cycling and storing nutrients and pollutants and can reduce the incidence of pathogenic marine bacteria, which not only directly protects humans, but also reduces diseases in coral reefs and contamination in seafood. Additionally, seagrasses provide cultural benefits worldwide by supporting tourism and recreational activities.
Seagrasses provide powerful nature-based solutions to tackle climate change impacts, as a key component of mitigation and adaptation efforts. Despite covering only 0.1 per cent of the ocean floor, these meadows are highly efficient carbon sinks, storing up to 18 per cent of the world’s oceanic carbon.
Seagrasses can also buffer ocean acidification, thus contributing to the resilience of the most vulnerable ecosystems and species, such as coral reefs, and act as the first line of defence along coasts by reducing wave energy, and by protecting people from the increasing risk of floods and storms.
Healthy seagrasses provide a source of opportunities to mitigate climate change, adapt to future changes, build resilience, provide food security and offer a wide range of additional societal benefits.
What We Do
Seagrass meadows and other blue ecosystems deliver effective nature-based solutions, and it is critical that we act now to protect, restore, and sustainably manage them so they can continue to deliver critical ecosystem services for nature, people and the planet.
UNEP provides global leadership on seagrass ecosystems, promoting international cooperation and science-based and ecosystem-based management approaches, supporting regional and global assessments (see UNEP’s latest report on seagrass), developing best practice manuals, and working with partners to implement conservation and restoration projects on the ground.
Seagrass protection and restoration is also central to the UN Decade on Ecosystem Restoration (2021-2030) which seeks to galvanize efforts to restore degraded and destroyed ecosystems to enhance food security, clean our air, secure freshwater supplies, address the climate crisis and protect habitats that support life on Earth. The UN Decade of Ocean Science for Sustainable Development (2021-2030) also highlights seagrass as an ecosystem to inspire advances in science and technology to improve ocean health.
Facts
- Seagrass meadows provide valuable nursery habitat to over one fifth of the world’s largest 25 fisheries.
- Seagrass meadows cover only 0.1 per cent of the ocean floor, but they are highly efficient carbon sinks and store up to 18 per cent of the world’s oceanic carbon.
- Seagrasses have been declining globally since the 1930s, with the most recent census estimating that 7 per cent of this key marine habitat is being lost worldwide per year, which is equivalent to a football field of seagrass lost every 30 minutes.
- The benefits from conserving and restoring seagrass meadows can help countries achieve 26 targets and indicators associated with 10 Sustainable Development Goals (SDGs).
Agreements and Conventions Relevant to UNEP’s Mandate on Seagrass
- United Nations General Assembly (UNGA), in Resolution A/RES/76/L.56 proclaimed 1 March as World Seagrass Day, to be observed annually.
- United Nations General Assembly (UNGA), in Resolution A/RES/71/257 on Oceans and the law of the sea notes the vital role seagrasses play in providing ecosystem services that offer a range of benefits including sustainable livelihoods, food security, biodiversity conservation, and coastal protection.
- The Ramsar Convention on Wetlands is a relevant policy framework for conserving and managing coastal wetlands, including seagrasses and other coastal ecosystems.
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