Are the world’s seagrass meadows healthy enough to combat climate change?

Carbon sequestration superstar

Effective protection and management of the world’s seagrass meadows could play a vital role in mitigating climate change. How? By sequestering carbon dioxide dissolved in the ocean resulting from our emissions.

Seagrass, a deciduous marine plant that excels at photosynthesis, exhibits astonishing carbon sequestration efficiency. According to the WWF, seagrass:

• Captures carbon up to 35 times faster than tropical rainforests;

• Covers 0.2 % of the seafloor; and

• Accounts for more than 10 % of the total ocean carbon storage.

Seagrasses have the potential to make a significant and measurable contribution to the carbon emission reduction goals of countries worldwide.

The Intergovernmental Panel on Climate Change (IPCC) recognises seagrasses as one of the most effective natural solutions to combat climate change due to their carbon sequestration capabilities. In fact, the IPCC named seagrass as one of the world’s three ‘blue carbon’ ecosystems (along with mangroves and salt marshes).

Highly productive ecosystem

Seagrass meadows are also vital from a biodiversity standpoint, supporting a wide range of creatures, including multiple species of fish, crustaceans, and molluscs. The protection and food they provide make seagrasses the ideal nursery for young marine organisms and the perfect habitat as they mature.

Seagrasses perform many important additional functions, including:

• Dampening the force of waves, thereby mitigating wave damage.

• Providing effective protection against coastal erosion.

• Recycling nutrients.

• Facilitating the thriving of other ecosystems, such as mangroves and coral reefs.

• Filtering seawater, improving its quality by removing bacterial pathogens. It’s estimated that this service reduces the annual incidence of cholera by around 600,000 cases a year.

As outlined above, seagrass meadows work wonders for our planet, playing a key role in biodiversity, coastal protection, filtration, nutrient recycling, and the global fight against climate change. It’s vital to preserve and restore them.

Where are the world’s seagrasses?

It’s often assumed that this flowering marine plant is found only in shallow, sheltered coastal waters. However, most of the world’s seagrass meadows can be found in far deeper water, growing on the seabed up to 50 metres below the surface. Despite their vital importance in regulating the planet’s health, only around 20% of the world’s seagrass meadows have been reported on so far, with very low coverage in many areas, such as the Indian Ocean. Moreover, the reporting to date merely indicates whether seagrasses are present in a location or not. Given the Earth’s climate emergency, there is an urgent need to map, monitor and manage seagrass worldwide. Importantly, it’s not just the location and size of the seagrass meadows that need to be monitored – assessing their health is even more important.

What’s affecting seagrass health?

It’s estimated that the world has been losing around 110 km² of its seagrass meadows annually since 1980, with indications that the loss rate is accelerating. Numerous factors contribute to this decline, including destructive bottom trawling, pollution, sedimentation, nutrient enrichment, and climate change. Understanding the reasons behind the deterioration of these critical ecosystems and their health is essential to realistically hope for their restoration and thriving preservation.

Why is seagrass health important?

Healthy seagrass meadows efficiently sequester carbon from seawater, partially storing it in the sediment (though not all is retained – some is released and remineralised). As seagrasses grow, their storage capacity increases. Over time, accumulated organic matter forms an interwoven mat of vegetation, holding the seagrasses in place while securely locking away carbon. However, when seagrass health declines, carbon sequestration becomes less efficient. Persistent issues lead to the destabilisation of the decaying mat, releasing captured carbon back into the system. This deterioration also releases other climate gases, posing significant concern from a climate-change perspective.

Mapping and monitoring urgently needed

Despite their exceptional carbon sequestration abilities, seagrasses are often overlooked due to a lack of data about their distribution and health. This resulting lack of recognition and protection could explain why seagrass meadows often don’t feature in policy-making and decisions about how best to tackle climate change.

The UN’s 17 Sustainable Development Goals (SDGs) include Goal 14 (Life below water), highlighting the importance of conserving and sustainably using the oceans, seas, and marine resources. However, in 2022, the UN stated that Goal 14 had received the lowest amount of public funding among all the SDGs. Urgent efforts are needed to map seagrass meadows worldwide, monitor their health regularly, and identify the causes of any changes occurring. Armed with this knowledge, governments can take action to protect and nurture these critical ecosystems. To maximise the ocean’s enormous carbon sequestration potential, seafloor restoration and preservation projects need to start immediately – and financial considerations must not impede progress.

Fugro and PlanBlue partnership

Fugro and PlanBlue have forged a collaboration to advance habitat mapping technology, using diverse cutting-edge methodologies. Conventional ground-truthing techniques for large-scale mapping are laborious and time intensive. To address this challenge, PlanBlue has developed a sensor payload and streamlined process optimised and accelerated through artificial intelligence (AI).

As the global Geo-data expert, Fugro specialises in comprehensive multi-scale hydrographic solutions. Its expertise encompasses a wide array of technology, including remote and autonomous underwater vehicles equipped with advanced sensors. In parallel, PlanBlue brings proficiency in advanced (hyperspectral) imaging and AI-driven data processing to the partnership, ensuring a well-rounded collaboration.

The combined strengths of Fugro and PlanBlue promise to revolutionise habitat mapping, offering innovative solutions for environmental conservation and management. Through hyperspectral imaging, PlanBlue's technology enables the partnership to detect, for example, chlorophyll levels in seagrasses, facilitating rapid, accurate, and scalable assessments of plant health and the identification of areas requiring restoration.

In this way, both Fugro and PlanBlue play pivotal roles in the collaboration, contributing their expertise equally for mutual benefit. The partnership aims to systematically study and document critical marine ecosystems, including seagrasses and corals, to enhance underwater mapping and modelling, thereby informing better decisions for ocean conservation and use.

Waking up to the importance of seagrass

Seagrass comes in various types, with some species maturing faster than others. However, as a general rule, they take between one and five years to reach maturity., Therefore, the quickest way to bolster seagrass population is by nurturing existing ones.

The partnership between Fugro and PlanBlue signifies a dedication to driving positive change through technological innovation. It stands as one of many significant strides taken to maximise the global carbon sequestration potential of seagrass.

For example, Italy’s government initiative, the Marine Ecosystem Restoration (MER) project, embedded within its National Recovery and Resilience Plan, aims to restore the nation’s marine habitats, and enhance the monitoring of marine and coastal ecosystems.

In this endeavour, the collaborations between Fugro and PlanBlue will play a pivotal role. Our efforts will encompass comprehensive mapping of coastal habitats across the entire Italian coast, with specific focus on seagrass meadows. The world is starting to recognise the importance of its seagrass habitats.

Food for thought

Seagrasses play a crucial role in maintaining our planet’s equilibrium by sequestering carbon and securely locking it away in the seafloor. To thrive, seagrasses require undisturbed growth within a healthy ocean – clear blue water at the optimal temperature, free of pollution, and eutrophication.

Encompassing around two-thirds of the Earth’s surface, the ocean is often described as the cradle of life, playing an immense role in supporting our planet’s health.

Without urgent and sustained action to conserve, protect, and restore the ocean and its seagrasses, we all may face dire consequences.