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Coastal Habitats - Creation    Threats    Conservation   

Coastal areas are used for many functions, and these often conflict with one another.  Think about the Northumberland coastline, we have farms, industry (such as the Alcan Plant), tourism (e.g. Seahouses), residential areas (Blyth) and Conservation areas (Seaton Sluice sand dunes and the Farne Islands).  Not all of these land uses fit with one another or are compatible with one another.  However, coasts provide valuable habitats for lots of species and despite all of the land uses there is a recognised need to protect and conserve our vulnerable and precious coastal habitat.
Aerial view of Keyhaven Salt Marsh Think about it

Find out how Hampshire council manages
Keyhaven Nature Reserve

Take a
picture tour of Keyhaven

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A case study of a coastal habitat  - Hurst Castle and Keyhaven salt marshes

How Keyhaven salt marshes have been created; 

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  1. Keyhaven marshes are located on the south coast of England, in the western Solent in Southern Hampshire. They have formed behind Hurst Castle Spit, which has formed because of longshore drift from the West.
  2. This spit provided a sheltered place for sediment accumulation and for eel grass to accumulate away from the impact of strong winds and coastal erosion.
  3. The pioneer colonising plant, eel grass, helps to stabilise the area further by trapping more sediment.
  4. Gradually, halophytes (salt tolerant plants) such as glass wort and sea blite colonise the accumulating mudflats.
  5. These plants trap more sediment and contribute organic matter when they die.  These processes help the salty marsh to grow.
  6. Eventually the salt marsh will grow further and an even more complex set of plants will colonise the area, until the climax community of alder and ash trees is reached, with a fully developed creek system. This is known as vegetation SUCCESSION.

Eeel grass Eel Grass

 Glasswort Glass Wort



Keyhaven salt marshes are under threat from the construction of groynes down current (to the West), which were designed to trap sediment for some of the South coast beaches.  The effect of this has been to starve the spit behind which the salt marsh ecosystem has formed and relies upon for shelter.  This human modification of the coastline had major ramifications for this ecosystem.  This has weakened the spit and at times it has been eroded and breached by erosion. This has led to the die back of Spartina Anglica and threatens the overall health of the salt marsh.

The marsh is retreating by up to 6m a year, and is threatened by sea level rise and storms.  In 1989  a storm in December pushed part of the shingle onto the top of the salt marsh, exposing up to 80m of salt marsh to the sea.  Over the next 3 months lots of erosion of this section of marsh took place.

Animals also graze on the marsh damaging the marsh, and tourism is becoming increasingly important.

View Keyhaven in a larger map 

Conservation and management;

A shoreline management plan was put in place in 1996 which added 300,000 cubic metres of shingle to the spit, and added 550m of rock armour at the western end of the spit.  It is hoped that this will stabilise the salt marsh.

The marsh is also a SSSI (Site of Special Scientific Interest) and part of a National Nature Reserve. This is to protect the biodiversity and plants of the area and so the area is carefully monitored and managed to help maintain this biodiversity.



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