From the tropics to the Arctic circle, seagrasses are amongst the most widespread coastal habitats on the planet, existing in 159 countries. They are essential both for many migratory species of wild animals, as well as for climate change mitigation.

A Critical Habitat for Migratory Species

Thousands of species depend on seagrasses for food, nursery grounds, and shelter.  Many others may use seagrass habitats as an important site for feeding along their migratory routes. Migratory seabirds and waders prey on fish, crustaceans and many other invertebrates that use seagrass meadows as nursery grounds. Juvenile sharks as well find those habitats ideal for hunting. Endangered species such as Dugongs, Manatees, and marine turtles use seagrass meadows as foraging and breeding grounds. These herbivores mainly depend on seagrasses as their primary food source. Dugongs, also called sea cows, can consume up to 30kg of seagrass daily.

Dugongs and other migratory marine megafauna also act as engineers of seagrass habitats, contributing to their maintenance. They play an essential role in generating and sustaining diversity, and helping increase their productivity by attracting other species and transporting the organisms that live on them between seagrass beds. Green turtles keep seagrass meadows healthy by shortening the plants, thereby preventing them from suffocating.

Nature-based Solution for Climate Change Mitigation and other ecosystem-services

Seagrass meadows are highly effective in mitigating climate change by sequestering CO₂ and providing an important source of oxygen in the ocean. While they only occupy 0.2% of the world's oceans, they account for 10% of the oceanic capacity to store carbon. In the process, they take carbon dioxide from the water and store it in the mud through their root systems. In certain environments, they can absorb carbon at rates faster than tropical rainforests.

These marine plants also provide many other benefits. They can help reduce coastal erosion and maintain ecological connectivity with adjacent ecosystems such as mangroves or coral reefs. They contribute to food security by providing habitat for juvenile fish, improve coastal water quality by filtering pollutants, and protect shorelines against extreme weather events.   

© Ben Jones

Threatened Habitats

Unfortunately, these vital marine ecosystems are in danger. A combination of natural and human-induced threats such as destructive fishing practices, coastal development, nutrient run-off, pollution, invasive species, and climate change have led to a 29% loss in global seagrass meadows over the last century. But since 1990 the loss rate has become so important that the equivalent of two football fields of seagrass is vanishing every hour, making it among the most rapidly declining ecosystems on Earth.

CMS Efforts on Seagrass Conservation

Protecting migratory species and their habitats is the primary goal of the Convention on the Conservation of Migratory Species of Wild Animals (CMS), an environmental treaty of the United Nations that brings countries and experts together to work on conservation solutions and addressing threats.

Ecological Connectivity between marine habitats

Along with its partners, the CMS Secretariat and its coordinating unit for the CMS Memorandum of Understanding for the Conservation and Management of Dugongs and their Habitats (CMS Dugong MoU) have been leading several projects dedicated to seagrasses.

The Dugong & Seagrass Hub has established a community portal for practitioners, researchers, and coastal communities. The online platform, launched in 2021, shares tools, experiences, and lessons-learned while working to conserve seagrass ecosystems in dugong range states.

The Seagrass Ecosystem Service Project is another important initiative focusing on seagrass ecosystems and the biodiversity they support across the Indian and Pacific Ocean basins. The project is grounded in a) innovative models of conservation that sustain seagrass health while reducing the vulnerability of coastal communities, b) assessment of seagrass ecosystem services to build arguments and engagement strategies that resonate with policy- and decision-makers, and c) acknowledging the central role that local communities must have in seagrass conservation and monitoring, as they are unique beneficiaries of these ecosystems and are disproportionately reliant on these habitats and ecosystem services for their well-being, livelihoods, and food security (commercial and subsistence fishing).

The Dugong and Seagrass Conservation Project (2015-2018) developed by the CMS Secretariat was unique in being the first coordinated approach to enhance the effectiveness of conservation of Dugongs and their seagrass ecosystems through community-based stewardship, incentive-based conservation, removal of knowledge barriers, and national and regional mainstreaming activities.

International Recognition

The contributions of seagrasses to sustainable development and climate change mitigation have recently received further international attention. The UN General Assembly adopted Resolution A/76/L.56, which initiated the observance of the 1st of March each year as the UN World Seagrass Day. The establishment of the UN day is set to spur educational and awareness-raising activities on the critical importance of this habitat for marine wildlife and human well-being.

A recent report, Out of the Blue: The Value of Seagrasses to the Environment and to People, released by the United Nations Environment Programme (UNEP), provides a comprehensive synthesis of the current knowledge of seagrass ecosystems and recommends a set of 13 actions for the halt and reversal of the global seagrass loss trend. The report also suggests that by protecting and restoring these marine habitats worldwide, countries may achieve several Sustainable Development Goals, as well as pledges made for the current United Nations Decade of Ocean Science for Sustainable Development and the UN Decade on Ecosystem Restoration (2021-2030).