Seagrass is a wonderfully understated plant; not at all showy to look at perhaps, but remarkable in so many more important ways.  

Seagrasses are not seaweeds, despite initial appearances - they are one of few groups of flowering plants that live wholly in the sea. Seagrass typically grows in the intertidal or subtidal zones as thick meadows. The shelter these provide is an important habitat for a wide range of vertebrates and invertebrates, including flatfish, seahorses, gastropods and crabs. They are an important food source too, for example for wintering wildfowl such as wigeon and brent geese. 

The binding action of their root-like rhizome system stabilises the sediments they grow in, thus resisting coastal erosion and sediment dispersal.  They can also act to remove excess nutrients and other pollutants from the water column.

If there is one property of seagrasses that is currently attracting most attention, it is their potential for the long-term storage of carbon - “blue carbon”, as it is called. Seagrasses, like mangrove and saltmarsh, store carbon as they die and accumulate in layers of sediments that form on the seabed. Their relatively rapid life cycle means that they store carbon at some 35 times the rate that tropical rainforests do.  As carbon is stored as sediment rather than as biomass, it can be stored for millennia rather than for decades, provided it is left undisturbed. 

Such is their impact on their environment that they can be described both as “ecosystem engineers” and a “keystone species” for the coastal environments where they live.
 

There is just one problem with seagrass. There simply isn’t enough of it.  Estimates suggest that seagrass habitats are being lost globally at a rate of around 7% per year. Unfortunately, their preferred habitats are under extreme pressure owing to a number of human factors including marine pollution, coastal development, dredging and bottom trawling.  An influential 2021 study showed that in the UK, over 90% of our historical seagrass habitat has been lost or has become very fragmented, with half of this loss having happened since the 1980’s.

Stemming this loss, and restoring coastal habitats to something resembling their former glory is an important tool in our attempts to mitigate anthropogenic climate change and to restore the health of our coastal ecosystems. 

It was with this in mind that the Yorkshire Wildlife Trust, Lincolnshire Wildlife Trust and green energy provider Ørsted launched the five-year Wilder Humber programme in April 2023. 

Part of this programme involves the restoration of 30 hectares of seagrass on the landward side of the Spurn Peninsula. This is what took me to Spurn Nature Reserve on a beautiful bright day at the end of August. I joined AJ and Georgia from YWT’s Seagrass Project Team, along with Jasmine and Sian from Lincolnshire Wildlife Trust and we headed down to the project site which is within view of Spurn lighthouse.
 

The Seagrass Restoration Project has a definite yearly routine. At this time of year, the team focuses on collecting seeds from the existing seagrass meadows, so this was our task for the day. The seagrass plants - specifically dwarf eelgrass, Zostera noltii, set seed in July and August.  These develop in seed pods that are up to about 1 cm long. Mature pods contain as many as five tiny (millimetre-scale) seeds and, as AJ showed me, are a distinctive pale green colour. 

After a safety briefing we donned waterproof trousers, and grabbed a polystyrene bodyboard each. We then sploshed a short distance across the mudflats to where the eelgrass is growing in and around shallow intertidal distributary channels and pools. You have to be careful where you walk, to avoid trampling the seagrass. The body boards gave us a degree of comfort and, more importantly, by spreading our weight they protected the mudflat and the seagrass as we worked.  This involved lying or kneeling on the boards that we had placed on the edge of the seagrass growth then pinching off the seed pods from the growing tips of the plants. 
 

The seed pods went into plastic containers that are then emptied into a large barrel for return to the project workroom for sorting and collecting. Once this is done, the seed pods are left to rot, with the seeds falling to the bottom of the barrels they are held in. These are then collected and stored for planting in the winter and spring.

The team face some logistical challenges, which I learned about as we worked and talked. Regulations issued by Natural England mean that they are only allowed on site to collect seeds for 12 days per year. This is standard for SSSI’s (Sites of Special Scientific Interest) like Spurn and is to minimise bird disturbance. Moreover, it is only possible to collect for a period of about two hours either side of low tide. Because of this we really had to make our time count - I noticed that whenever I had a bit of a break to take photographs or do a bit of wader watching, the team were all still hard at work. Another challenge for the team is that seed development is hard to predict. Fortunately on the day I visited there seemed be an abundance of mature seed pods, and our little collecting pots soon filled up.

Although there is a set pattern to their working year, the team are still developing and refining their protocols for planting, monitoring and seed collection. This has been helped by exchanges with other seagrass restoration teams around the country.  The Spurn team all expressed the wish to be able to do more to share their experience and to visit other locations to get hands-on experience of what some of these teams are doing. A number of other Wildlife Trusts, including Hampshire and Isle of Wight, and North Wales have their own seagrass restoration projects too. Looking further afield, seagrass has huge potential for carbon storage - estimates suggest that they store 10% of all oceanic carbon globally, despite covering just less than 0.1% of the sea floor!

Our time was soon up as we could see the tide moving in on us with gathering pace, so we collected all the gear together and headed back to the Spurn Field Station where the team has its base. 

There can be few altogether more harmonious ways of combatting climate change and increasing biodiversity than helping nature help itself. Such is the way with the Wilder Humber Project, so it was really good to the witness seagrass team in action.  Great too to see and hear about the cooperation between all three stakeholders in the project - Yorkshire Wildlife Trust, Lincolnshire Wildlife Trust and Ørsted…and who knows, the seagrass growing from those seeds we collected might be one day contribute to our battle with climate change… 

If you have been interested in Simon’s story, you can find more stories from the “Telling our Story” team here.  You can read more about the Wilder Humber Project and Yorkshire Wildlife Trust's partnership with the Lincolnshire Wildlife trust and Ørsted here