Successful start to vital saltmarsh restoration trial at River Hamble nature reserve by Solent Seascape Project

A critical coastal habitat, saltmarsh provides many crucial benefits to the Solent area, including flood defence, increased wildlife, fish nurseries, improved water quality and carbon capture. 

It is in decline both nationally and locally, facing pressure from coastal development, sediment loss and rising sea levels. This is leading to a decrease in size, from which it is struggling to recover naturally. Its continued loss means urgent action is needed to reverse the rate and scale of decline. 

The team, which included staff from Blue Marine Foundation, the University of Portsmouth, RSPB and Coastal Partners, along with help from Hampshire County Council’s rangers, spent a week in August creating 12 creek barriers, with the aim of restoring the diminishing, but important habitat.

To achieve this, they hauled 107 three-metre-long coir rolls into place, knocked in over 330 chestnut stakes, and lashed it all together with over 400m of manila rope, creating over 107m of biodegradable barrier. 

The work follows comparison of historic records dating back to 1870, which showed the creeks within the wildlife-rich marsh to be widening, decreasing the area of saltmarsh. The barriers are designed to trap sediment, stopping it from further washing away and allowing creeks within the marsh to return to the same level as the surrounding saltmarsh. This should eventually restore the threatened habitat, which is an important feeding area for waders and one of only two sites in Hampshire where unimproved pasture transitions to saltmarsh naturally, without seawalls or invasion by common reed.

Using knowledge gained from Essex Wildlife Trust’s saltmarsh work, Dr Luke Helmer, Restoration Science Manager at Blue Marine, and Professor Joanne Preston from the University of Portsmouth, designed a system that is completely biodegradable and allows restoration to be potentially ‘fast-tracked’ in areas where large machinery and other methods can’t be used.

Professor Joanne Preston from the University’s Institute of Marine Sciences, explained: “Systems such as this one can be installed with relative ease and limited specialist equipment. It has the potential to provide a method that can be used by citizen scientists, communities and other voluntary or conservation groups across the UK and beyond.  Our scientific monitoring of the marsh will measure the changes in biodiversity and carbon stored as a result of this exciting restoration method.”

“No restoration work happens quickly, particularly saltmarsh, so I’m intrigued to see if we can accelerate this. I am optimistic that we will see some positive results over the next few years that might enable others to follow suit,” added Dr Helmer.

The second stage will test a novel approach. Following the discovery in Essex that saltmarsh plants establish extremely quickly on the coir barriers, coir matting will be placed over the sediment build-up within the creeks to help saltmarsh plants, such as glasswort, sea purslane, thrift and sea lavender, to establish more rapidly here as well. Some of these creeks will then be planted with ‘plugs’ of appropriate saltmarsh species. It is hoped that the root systems of the plants that establish will stabilise the sediment and a healthy marsh will once again inhabit the creeks.  

The work to tackle the loss of this habitat across the Solent follows another innovative trial last year to restore saltmarsh within Chichester Harbour led by the Solent Seascape Project in partnership with Chichester Harbour Conservancy. Within six months, the first shoots of glasswort had started to recolonise the previously degraded area. 

With the project’s aim to restore 8 hectares within five years, further saltmarsh restoration work is also planned at Langstone Village within Chichester Harbour, and at three sites across the Isle of Wight: Werrar marsh within the Medina estuary, at Thorness Bay and within the Western Yar. 

East Head Impact and the Endangered Landscapes & Seascapes Programme (ELSP), managed by the Cambridge Conservation Initiative and funded by Arcadia, support the Solent Seascape Project.

Earlier this year, the project was endorsed by the United Nations (UN). You can find out more about the Solent Seascape Project, follow their work and sign up for their newsletter here: www.solentseascape.com. 

Photo credit: Luke Helmer