Blog by David Mason, National Trust Suffolk and Essex Coast Ranger for Northey Island
Much of the saltmarsh at Northey Island is in poor health, eroding due to climate change and rising sea levels. Improving the condition of the saltmarsh will help to limit the impacts of climate change and make space for nature to thrive.
Creating new saltmarsh
The South East Embankment is in poor condition, regularly being overtopped by high tides. In the coming years we plan to create new saltmarsh by removing sections of this embankment, as we did at the south of the island in 2019, in a process called managed realignment. In preparation for this, in 2022 we are excavating new creeks in the East Field. This will help create healthy saltmarsh when we breach the embankment in the next few years by bringing silt and seed into the former field and allowing it to deposit and build up along the banks.
On the face of it creating saltmarsh might appear simple. Remove the sea walls to let in the tide and allow the tide and natural processes to deposit silt and seeds to grow new habitat. This however is only the visible part of it. Species and habitat monitoring and satisfying the regulatory bodies; translocation of protected species and creation of compensatory habitat; gaining funding from internal and external national and international funding bodies and reporting to them; analysis of the expected natural processes, careful design of the new infrastructure and navigating the marine regulatory process; moving existing infrastructure; ongoing monitoring to measure the effects of the changes; managing contractors, staff and volunteers; and explaining it all to members of the public and colleagues: all these factors and more go into Saltmarsh protection and re-creation.
This video gives an overview of the site and project aims.
In February a surge tide came over the South East Embankment and flooded part of the island.
This demonstrates why we need to consider how we manage Northey Island in the face of sea level rise and climate change. The overtopping of the embankments is not uncommon, happening at least annually and the frequency will increase into the future.
The area of water gives a rough idea of where the tide will come to when the embankment is realigned. As sea levels rise further the new saltmarsh will progress even further onto the land. The water has now receded but is a reminder of why we continue to do our work at Northey Island.
Removing overhead powerlines.
Since the last blog there have been a few changes on site. Perhaps the biggest is the removal of the power lines that crossed the fields and the burying of new cables to the houses. Some of these power poles were in areas that will become saltmarsh. This has made a great difference to the landscape and will allow more safe access for birds flying into the fields, including the Brent Geese that come in during the winter to roost and feed. We have left some poles in place, cut down in height, and plan to install nesting boxes to the tops of the poles in the hope of enticing oystercatchers and other estuary birds to breed here.
As small cogs in that project machine at Northey Island, the volunteers and I have been supporting this work.
The Essex and Suffolk National Trust Volunteers helped to paint the new hide which looks out over this area. They also weeded and mulched new hedging, watered new plants around the pond in the dry weather in early spring and cleared up a large amount of litter from the foreshore, including the flotsam and jetsam brought onto the island by the surge tide. They have also helped to prepare the ground for a new footpath through the fields to the hide.
Marsh harriers are regularly seen over the saltmarsh and a variety of birds have been using the area around the new scrape near the hide including yellow wagtail, shelduck, snipe, little egret, curlew, lapwing, teal, mallard, and shoveler. Cuckoos and whitethroat can be heard through the summer and Brent geese roost on the grass fields during the winter. Hopefully there will be plenty to see, looking over the developing saltmarsh, when the hide is open to the public. The hedges and grassland are alive with butterflies and walking along the access road in June and July surrounded by clouds of Meadow Browns feeding on the privet is mesmerising.
A new freshwater pond has been created near the hide which will provide a more stable and favourable home for the water voles that currently reside in an unsustainable area. Once new pond side vegetation is fully established the plan is to translocate the voles to their new home. Diving beetles, water boatmen, pond skaters and dragonflies are already colonising these areas.
Improved resilience to change
Further locally dredged sediment has also been placed in the north-west of the island to raise up the saltmarsh. This will protect saltmarsh in this area, avoiding new channels being formed and reducing higher water flows over the saltmarsh which cause erosion and vegetation loss. This work has allowed further sediment to be deposited in the saltmarsh by the tides, building up the marsh and allowing saltmarsh plants to regenerate. This is improving diversity and creating rare upper saltmarsh where the marsh transitions into the terrestrial land.
A section of bank has been reinstated at the north of the Island which has a shallower profile that will be better able to cope with overtopping by high tides, allowing water to run off without damaging the bank. This will help to protect the north of the island as sea levels rise. Topsoil will be spread to allow it to revegetate quickly.
While patrolling the site and talking to visitors, answering email enquiries, and even commissioning the signs from the printer, explaining the aims and progress of the project to visitors and the local community is an important part of my role. The project featured in the National Trust member’s magazine reaching more than 5 million members. The Northey Island website has also been updated with project developments. https://www.nationaltrust.org.uk/northey-island
Blog by David Mason, National Trust Ranger - Suffolk and Essex Coast
‘Increasing the extent and health of the saltmarsh area improves biodiversity and provides a range of other ‘ecosystem services’ (things that saltmarsh delivers for society) such as natural flood allevation, reductions in wave energy, spawning and nurseries for fish, providing food and shelter for birds, and locking up carbon dioxide to reduce the effects of climate change.’
I write this, the first Ranger’s blog from the Northey LOTE project, after visiting Northey Island on the Blackwater Estuary on the Essex coast. It was a bright November afternoon on a falling tide and as I approached the tidal causeway that links it to the mainland the last Lapwing and Dunlin were leaving the causeway to feed on the newly exposed mud. In the distance a flock of Golden Plover were glowing in the sunlight, reflected in the glistening mudflats. This is a spectacular place to see coastal birds when large flocks of waders and wildfowl gather on the estuary to feed and roost.
Several years ago, I saw c.5000 Brent Geese land on a site on the Suffolk coast during an October storm as they came in to land for shelter, skein after skein, on their migration South. They left the next morning when the weather cleared and I wondered if I had dreamed it!
I had heard that the Blackwater Estuary was a hotspot for them and have been delighted since starting work on the Essex coast last November to see where they were heading: Northey is a refuge for them in the winter where they roost and graze on the grass fields and on the saltmarsh as the tide comes up. In February I spent a happy morning clearing a footpath for the new circular visitor route we put in place this year, working with hand tools to minimise disturbance, while the geese chattered quietly in the field nearby.
I first visited the site in 2019 as the work to realign the South Embankment was being undertaken. This work was finally completed this year after delay in 2020. The mud from the embankment was placed in the ditch behind it (from where it had originally been dug in the mid-1800’s) to reform the natural landscape; the realigned area has now been naturally colonised by a wide range of saltmarsh species such as sea purslane, samphire, sea aster and sea beet as the tide has flooded the area, bringing in seed from the surrounding area. This area grades into a rising grassland bank which as sea levels rise will become new saltmarsh but now provides a rare transitional area between the saltmarsh and terrestrial grassland.
Now the pressure of coastal squeeze has been reduced, it is also notable that the saltmarsh in front of where the embankment was (which was heavily eroded) is also showing some signs of recovery with sediment depositing and new saltmarsh vegetation growing. I am impressed at how quickly this has established from bare mud. Allowing the coastal processes to function naturally without the constraints of man-made structures seems to be key. There is an increasing urgency to carry out more of this work for nature conservation as existing saltmarsh is rapidly eroding due to sea level rise and coastal squeeze on saltmarsh between the tide and coastal defences.
The island has been busy with contractors this year and new habitat and visitor facilities have been created and installed in preparation for future realignment of other embankments. Volunteers from the Essex and Suffolk National Trust group helped in maintaining the visitor route and picked up eight bags of litter from the foreshore.
There are a small number of water voles that live a marginal existence on Northey Island. The water voles’ homes and their numbers here have recently suffered from flooding from the sea (such as in 2013 and 2017/18) and hot dry summers. Part of our work in adapting to climate change and sea level rise is to create a new watery habitat for them. A new pond and ditch system has been created on higher ground which will provide a safer, more sustainable future home for Water Vole.
Coir rolls with pond plants embedded have been placed which it is hoped will provide food and shelter for the voles and other wildlife when they become established. This is overlooked by a new hide where visitors will be able to look over the pond, a new scrape and establishing saltmarsh.
A new scrape created this summer has filled with water and is already attracting Lapwing, Teal and Curlew amongst others.
In some areas dredged sediment from elsewhere in the estuary is being used to increase the resilience of the marsh. The adaptation of the coastal processes this achieves will prevent further erosion of saltmarsh in these areas. Eroded creeks that were bare mud a few years ago are already building up with natural silt deposited by the tide and recolonising with saltmarsh plants. The estuary side of the bank in this area includes some areas of shingle which provide another niche habitat and attracted 49 Ringed Plover in August, as noted on the regular bird (WeBS) count.
All in all it has been a fascinating year seeing the work progress and habitats develop and sharing it with visitors and volunteers and now you.
Photo credits: Oystercatcher by Katie Nethercoat (rspb-images.com)