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#30 - Turning the tide on seagrass loss

#30 - Turning the tide on seagrass loss

πŸ’‘ One idea: Turning the tide on seagrass loss

πŸ“ˆ One data figure: 3,000 tonnes of CO2 per hectare

✨ One success: Ulysses, a robot to plant seagrass at scale


πŸ’‘ Turning the tide on seagrass loss

As REDD+ projects and large afforestation programmes are momentarily getting out of fashion following recent scandals, blue carbon is the new trend in the nature-based solutions arena. Though arguably less Instagrammable than mangrove ecosystems, seagrass meadows are unfairly overlooked. Let me do them justice in this edition.

Seagrass are marine flowering plants found on the coasts of all continents. Unlike seaweeds that are algae, seagrass have roots and are anchored in the sand directly on the seafloor. Any Botanics nerd here certainly already knows that seagrasses are aquatic angiosperms. Because they require light to photosynthesise, they need clean and clear water. We usually find them in shallow intertidal water with a maximum depth of 10m.

On top of being a significant carbon sink (see below), seagrass meadows provide an incredible range of invaluable ecosystem services, as detailed in the excellent UN report Out of the Blue: The Value of Seagrasses to the Environment and to People, such as:

  • Wildlife habitat (fish and invertebrates)
  • Sediment stabilisation and coastline protection, by attenuating wave and tidal current forces
  • Water quality improvement
  • Green tourism and halieutic resources

Unfortunately, an estimated 7% of seagrass habitat is being lost worldwide every year. In about 100 years, 30% of seagrass areas across the globe have disappeared. This figure is much higher in developed countries. For example, in the UK, 90% of seagrass meadows have been destroyed by human activities such as dredging and pollution.

Protection and restoration initiatives are popping up everywhere but available solutions are often ineffective and expensive in practice. Upscaling seagrass restoration to functionally relevant scales still faces major hurdles:

  • Protecting ecosystems is needed but natural recovery is estimated to take up to 100 years. It is 10 times faster with human intervention.
  • Planting seedlings leads to tangible results but has to be done manually and takes so much time that it will never work at scale.
  • Sowing seeds is the more efficient way to go, but seeds can be washed away and predators such as shore crabs and urchins love them. Consequently, seeds are often put in small biodegradable hessian bags weighted with sand and laid on the seabed.

Seagrass meadow restoration still goes through trial and error, and remains costly and cumbersome, relying on the goodwill of a bunch of volunteers. Here is a very cool video about a restoration initiative in Wales. These projects are often part of scientific research programmes backed by charities rather than scalable commercial projects.

πŸ“ˆ Up to 3,000 tonnes of CO2 per hectare

Even though they cover only 0.1% of the ocean floor, seagrass meadows are highly efficient carbon sinks, storing up to 18% of the world’s oceanic carbon. Seagrass sequester CO2 in their leaves and roots, but it is primarily their efficient sediment accumulation capacity that enables them to bury organic carbon for the long term. Up to 3,000 tonnes of CO2 per hectare are captured deep in the seabed, which is 30 times higher than by forests!

A well-functioning seagrass ecosystem sequesters 1 to 2 tonnes per hectare per year. Because they are widely distributed across the globe, they could play a significant role in the fight against global warming.

Global distribution of seagrass (source)

Carbon project developers are certainly interested and a Verra certification methodology is already available (VM0033), but very few projects have taken shape. In Virginia (US), the Nature Conservancy intends to sequester 1,350 tonnes of CO2 per year with a seagrass restoration project, a good start but not yet a game changer. In the UK, stakeholders are pushing for the development of a dedicated Seagrass Carbon Code to facilitate investments in such initiatives. Stay tuned!

✨ Ulysses, a robot to plant seagrass at scale

You savvy readers may think that there is a huge opportunity to save the planet and sell a lot of carbon credits at the same time! If only it was possible to scale restoration activities... Well, this is exactly what Ulysses is doing.

This Irish start-up is developing a scalable and robust subsea robotic system for offshore seagrass planting. If successful, their robot will be able to do everything:

  • Collect seeds from existing seagrass meadows.
  • Inject seagrass seeds in the sand, with a unique planting method that increases germination success and meadow density by a factor of 50, and at a pace enabling the coverage of large areas at a fraction of the cost of traditional manual methods.
  • Monitor the development of planted meadows using advanced computer vision-based MRV systems to precisely track ecosystem coverage and carbon sequestration performance in real-time.

Fully automating seagrass planting would revolutionise ecological restoration efforts. Ulysses CEO, Akhil Voorakkara, is now out raising a pre-seed round led by a Tier 1 climate tech VC. I almost made an angel investment in it but the round was largely oversubscribed and I got kicked out last minute, too bad! Reply to this email if you want to know how I got introduced to this deal.


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β€” Colin Rebel
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