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Words & Pictures - Mark Deane

The line where land meets sea and skirts Wales' 1,000 miles of coast is the inter-tidal zone. This is the part of the shore which lies between the high and low tides, from the lichens at the top of the shore, through to the kelps at the bottom.

It is home to many varieties of seaweeds, starfish, shellfish, crabs, sponges, sea slugs and anemones. Each plant and creature lives in its specific habitat on the shore, whether a rock pool rich in seaweeds, boulders with assorted crabs, sponges and sea squirts or mud and sand flats with myriads of worms and shells or open rocky coasts with barnacles and mussels.


Each community is different, revealing subtle variations in the environmental conditions which give rise to it.

The UK Government is required by the European Union Habitats Directive to undertake measures for safeguarding biodiversity, including the management of marine Special Areas of Conservation (SACs).

The phase 1 inter-tidal survey conducted by the Countryside Council for Wales (CCW), aims to map biology and the associated rock or sediment, based on distinct marine inter-tidal communities of animals and plants found around the coast of Wales.

This is the first time such an extensive project has been set up to survey the whole of the coastline of Wales and illustrate it through detailed maps and site reports.

The surveys are undertaken between April and October and can be carried out two hours either side of low water on a spring tide.


Features of the shore are drawn or traced using aerial photographs. A team of marine biologists then works along the shore to identify the habitats and marine inter-tidal communities and add the detail to a sketch map. 

Target notes are written where habitats or communities cover too small an area to map, or to describe rare and scarce species, non-native species, nationally important habitats (biotopes), specialised habitats and artificial substrata. 

Further information which is collected includes shore type, tidal currents, and exposure to waves, human uses and impacts.

The coastline of Wales is widely varied and can be difficult to access. It ranges from large muddy areas, such as the Severn Estuary, to slippery cobbled shores affected by strong tidal currents, like the Menai Strait, or such rugged off-shore islands as Skomer and Ramsey in Pembrokeshire. 


Effective and consistent survey of the shores of Wales has required a team of marine biologists who are practical and able to cross rough terrain and access difficult landscape by boat.

Surveyors have be sensitive to other issues such as breeding seal and seabird populations, along with the ability to get up in the small hours to catch the early tides !

Wales is fortunate in having some of the least polluted estuaries and coastal waters in the UK.  In addition this varied coast provides habitats for a broad range of marine wildlife communities. 

There are many species of plants and animals that have their limits of distribution in Wales and can be used as good indicators of climatic change. 

Also occurring are nationally rare and scarce species, which are important nationally for their nature conservation value.

The inter-tidal survey undertakes assessments to consider the quality of the community in terms of species richness, size, presence or rare or scarce species and rare or scarce communities.


Consultations during casework and other developments in the inter-tidal survey can help to develop best practice and avoid damaging fragile communities.

The survey has also created a baseline for monitoring and the development of management strategies. It has been used to develop a sensitivity index to oil contamination and therefore can be used for oil spill contingency planning.

The maps produced help local authorities, national park wardens, nature reserve managers, coastal planners and others to be more aware about the seashore for which they have responsibility.

After 3 years the physical survey has been completed and the CCW is analysing the data with a view to producing a detailed report and recommendations.