The largest coastal re-alignment in Europe - occurred in Essex
Great Britain resulting in the tilting of the landmass to the south-east.
Above the saltmarshes and often behind sea walls there used to be extensive areas of grazing marshes.
Traditionally these saltmarshes have been grazed by sheep all year round, or with cattle in the
summer months. In 1946 the War Commission changed 90% of grazing marsh into agricultural land.
Essex has an extensive area of arable land - a proportion of which falls within the coastal zone.
Furthermore, sea level rise is particularly relevant to Essex where the coast is predominately low
lying that puts it at greater risk from flooding. The 1953 floods illustrate this when a tidal surge in
the north sea caused 1,200 breaches in the sea defences of East Anglia, pushing sea water up to 3 km
inland and resulting in 307 deaths (Clover 2003). As a result many Essex sea walls were reinforced
and raised. The saltmarshbecomes pinned between the erosion of the sea and afixed line of defence
that is known as coastal squeeze. It is estimated that the landward movement of low-water mark over
the next 20 years may be 10 metres.
Saltmarshes are areas of high primary productivity, similar to tropical rain forest (Long & Mason
1983). The inter-tidal mud flats of the Essex estuaries are nursery areas for sole, plaice and skate as
well as being commercially important for cockles and oysters. Together with the salt-marshes they
form exceedingly important feeding and roosting grounds for a very large number of birds (Hughes
2002). One of the major effects of saltmarshes in estuaries is the creation of organic matter that fuels
detritus-based food webs in the marsh and adjacent habitats which directly or indirectly, sustains the
invertebrates of the mudflats and deeper waters, and then birds and fish.
Coastal re-alignment is increasingly being viewed as a potentially useful technique in tenns of habitat
creation and coastal defence. The hard sea defences along much of the south-east England are both
protected by and contributing to the demise of the saltmarshes and mudflats of the inter-tidal zone.
Coastal re-aligmnent also offer the opportunity to reduce symptoms of coastal squeeze and a long-
term sustainable approach to flood defence in areas of rising sea levels. The rationale is based on a
combination of flood defence requirements and habitat creation to replace lost inter-tidal habitats.
The primary consideration in selecting an area suitable for managed retreat is therefore the impact
that the retreat will have on the estuary process.
Ironically the saltmarshes arc also important in reducing the impact of the sea on coastal defences
because they reduce wave action. Coastal squeeze not only results in the loss of Saltmarsh, therefore,
but also the increased vulnerability of the sea walls which require progressively more expense and
more hard engineering to maintain.
Colchester Borough Council awarded planning permission to Essex Wildlife Trust on 13th June
2002 to undertake 5 breaches in the sea wall at Abbotts Hall Farm, Great Wigborough. These breaches
were made in October 2002 allowed over 200 acres of low lying land behind 3.5km sea wall to be
flooded forming a more sustainable coastline. This scheme undertaken by Essex Wildlife Trust,
supported by Environmental Agency, World Wide Fund for Nature. English Nature and the Heritage
Lottery Fund created the largest coastal re-aligmnent in Europe last year.
Since the coastal re-alignment in October 2002 Saltmarsh plants have colonised the inter-tidal habitat.
Plants relatively tolerant of the conditions associated with immersion by seawater first colonise bare
sediment. The substrate of a new marsh can affect the degree of success with which new plants
colonise the site, particularly if accretion rales are low in the early stages. The plant species Abbotts
Hall are dominated by Glassworts Salicornia spp., Grass-leaved Orache Atriplex litoralis, Sea-
spurrey Spergularia spp. and Annual Sea-blite Suaeda maritima. The vegetation communities were
Essex Naturalist (New Series) 20 (2003)
109