Cuckmere Haven, the day after Storm Eunice, and the importance of Saltmarshes. 19.02.22
Updated: Feb 24, 2022
It was very windy today at Cuckmere Haven. I had planned to go to Pagham Harbour but the train track to Chichester was blocked all morning because of fallen trees as a result of Storm Eunice.
I took the 12X bus to Exceat (South Downs National Park, Seven Sisters Country Park Visitors' Centre from Brighton. It was a fairly short visit (11.00-14.00) as it started to rain heavily. I walked up and down the east side of the valley. The photographs are in chronological order.
Birds seen: Oystercatchers, Redshanks, Skylarks, Rock Pipits, Little Egrets, Teal, Shelducks, Herring Gulls, Great Black-Backed Gulls, Cormorants
Saltmarshes are important areas for small creatures such as worms, shrimps and shellfish, fish, wading birds and wildfowl. They provide nursery areas for fish, food for waders and wildfowl and nesting sites for waders and seabirds. Many of the plants growing on saltmarsh are not found anywhere else. Farm animals may graze on the upper parts of the saltmarsh. Saltmarshes may help with defence against the sea as they can reduce the force of the waves hitting sea walls.
Saltmarsh is found at only a few places in Sussex: mainly at the harbours of Rye, Chichester and Pagham and along the tidal reaches of the Rivers Rother, Cuckmere and Adur. The total amount of saltmarsh recorded in the region during the 1998 national survey was 816 ha. This is 4% of the resource on the North Sea Coast and 2% of that in Britain. More recently the BRANCH Project calculated the Sussex extent of saltmarsh as 405 hectares. This implies that we have approximately half of the saltmarsh resource previously audited. The saltmarsh at Cuckmere Haven represents a tenth of the total saltmarsh in Sussex. It is typical of the saltmarsh found along the south coast. It has formed on deposits of clay and silt eroded from the sedimentary rock of the Seven Sisters.
Threats to salt marsh
Sea level rise Sea level is rising due to climate change and also because the land along the south east of England is tilting towards the sea.
Sea defences Defences to protect the land from the rising sea may be built on saltmarsh or they may change the movement of the sediment necessary to maintain saltmarshes and mudflats.
Dredging Dredging to maintain the channels may also affect the movement of sediment and hence the state of the saltmarsh
Coastal squeeze Ideally saltmarsh need to be able to ‘move’ in response to changing conditions. Many saltmarshes are being 'squeezed' between the rising sea and fixed flood defence walls
Erosion Wave action (including wash from boats) can damage and erode the marsh Disturbance by people Recreational use, for example by trampling and creating informal footpaths, can damage saltmarsh.
Land claim for farming or building Since medieval times, saltmarshes have been enclosed for agricultural use or destroyed to make way for building ports, harbours and other infrastructure. Nowadays this happens only in special cases.
Pollution from land or sea; oil, sewage, fertilizers, run off from old waste tipping. Oil pollution can damage saltmarsh vegetation and whilst it usually recovers, sediment may be lost during the period of die-back. Water pollution from sewage and fertilizers can lead to eutrophication. This is the excessive growth of green algae, which may cause local problems
Cormorants and Shelducks at the top of the Oxbow Lake
This Oystercatcher and Carrion Crow look like they are having a barney; but actually what happened was: they were foraging close to each other, ignoring each other; then the Oystercatcher flew into the air and a very strong gust of wind blew it into the Crow.
Skylark in songflight
Skylarks are red UK conservation status. Their population decline is enormous, almost entirely because of agri-business wanting to increase crop yields (and thus profit) from more intensive farming. RSPB: "In the UK, the population halved during the 1990s, and is still declining. In the preferred habitat of farmland, skylarks declined by 75% between 1972 and 1996.
The main cause of this decline is considered to be the widespread switch from spring to autumn-sown cereals, which has resulted in a dramatic reduction in the number of chicks raised each year.
Autumn-sown cereals are taller and denser throughout the season. Fewer birds nest there, and those that do are unable to raise as many broods as birds in spring-sown crops. Many nesting attempts are on or close to tramlines (tractor tracks that are used to apply the many sprays to the crop), which makes the nests vulnerable to ground predators."
Redshank, in one of the lower scrapes. Redshanks are plentiful at Cuckmere Haven
Oystercatchers and Herring Gulls sheltering in one of the scrapes behind the shingle beach, sheltering from the strong winds
Little Grebe with fish in one of the pools
In winter, UK resident Rock Pipits are joined by many overwintering Rock Pipits from Norway. At Cuckmere Haven I always see them around the granite “rock armour” which was put along the sides of the river by the Environment Agency (managed by DEFRA). Most of the Rock Pipits I see in Sussex (along the undercliff, at Seaford, up the Cuckmere and Ouse estuaries) are at locations where rock armour is used for coastal “defences” or enforcing riverbanks. Much of the rock for the rock armour comes from … Norway!
However, reinforcing riverbanks and coastal defences reduces the extent of saltmarsh in the UK. The UK is enormously important for Arctic and northern European waders (godwits, oystercatchers, redshanks, dunlin, sanderlings, turnstones etc.), ducks (wigeon, teal, shovelers, pintails etc.), and geese (Brent and Pink-Footed etc); and they often overwinter on or near saltmarshes.
The reduction of saltmarshes, mostly through draining them, to build on them or turn them into arable land, is a major threat to some birds. But awareness is growing: RSPB Medmerry is a saltmarsh created by DEFRA and the RSPB working together, as salt marshes are good for birds and good at absorbing high tides so prevent flooding.
"Managed retreat" was planned for Cuckmere Haven; discontinuing the maintenance of the seawall and allowing the sea to encroach, producing more saltmarsh. But this has proved hugely controversial because it would probably see the end of the coastguard cottages, which are a big tourist attraction due to their use in various films.
The amount of saltmarsh that has disappeared over many year in the UK is huge; "declining by around 100 hectares each year" "Globally, it’s estimated we’ve lost about 50% of our saltmarsh, and in the UK it’s declining by around 100 hectares each year,” said lead author and SWEEP Impact Fellow, Dr Katrina Davis.
“These patches of coastline are squeezed by rising sea levels on one side, and repurposed into farm or development land on the other. Land used for farming or development has the perception of being ‘higher value’, but by looking at the whole picture – the knock-on effects to fish stocks, the cost of man-made flood defences, the benefits to health and wellbeing - you are able to appreciate the full value of saltmarsh.” https://www.exeter.ac.uk/.../rese.../title_701113_en.html...
The misuse of land in the UK (over-development and agri-business) has, to date, caused many local extinctions, and reductions in abundance, of native and migratory birds, and insects, though loss of breeding and foraging habitat.
A Mute Swan near the top of the Oxbow lake, buffeted by the wind
A Canada Goose in the river (very high tide)
Another Skylark, just descended from a song flight
Another Redshank at the top of the Oxbow lake.