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Introduction
Scotland's long, varied and dynamic coast is a landscape of outstanding beauty. It exhibits a magnificent diversity of features from sheltered sea lochs and exposed cliffs on the Atlantic west coast to the large, nutrient-rich estuaries flowing into the mud bottomed North Sea on the east. Earlier glacial activity has created this highly indented coastline, about 11,800 km in length, with some 800 islands mostly off the west and north coasts.
Coastal habitats are determined by geological structure, climatic conditions and prevailing local processes of tidal energy, erosion of the land and accretion of sands and gravels. The waters of the North Atlantic Drift, the Gulf Stream, keep the west coast climate warmer and wetter than that of the east coast. The Arctic waters from the north keep the Orkney and Shetland archipelagos, as well as part of the north east coast, cooler than much of the rest of Scotland. This physical diversity of Scotland's coast maintains a large species diversity, with many different and unusual communities of plants and animals.
A list of theHabitat and Species Action Plans that relate to Scotland's coastal environment is included in Box 3.1.
| Coasts and Firths: Species and Habitat Action Plans that relate to Scotland's coasts and firths |
box 3.1
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| Habitat Action Plans | ||
| Coastal saltmarsh Coastal sand dunes Coastal vegetated shingle Machair* Maritime cliff and slope* Mudflats Reedbeds* Saline lagoons Seagrass beds Sheltered muddy gravels Tidal rapids |
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| Species Action Plans: Vertebrate Animals | ||
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Allis shad |
Allis alosa |
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Corn bunting* |
Miliaria calandra |
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Corncrake* |
Crex crex |
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Natterjack toad |
Bufo calamita |
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Otter* |
Lutra lutra |
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Roseate tern |
Sterna dougallii |
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Reed bunting* |
Emberiza schoeniclus |
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Sand lizard |
Lacerta agilis |
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Twaite shad |
Allis fallax |
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Species Action Plans: Invertebrate Animals |
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Lagoon sea slug |
Tenellia adspersa |
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Mole cricket* |
Gryllotalpa gryllotalpa |
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Narrow-mouth whorl snail |
Vertigo angustior |
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New Forest burnet moth* |
Zygaena viciae |
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Species Action Plans: Vascular Plants |
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Dune gentian |
Gentianella uliginosa |
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[An endemic eyebright] |
Euphrasia campbelliae |
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[An endemic eyebright] |
Euphrasia heslop-harrisonii |
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[An endemic eyebright] |
Euphrasia rotundifolia |
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Rock sea lavender |
Only Limonium recurvum ssp. humile in Scotland |
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Scottish scurvy-grass |
Cochlearia scotica |
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Species Action Plans: Non-vascular Plants & Fungi |
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Baltic stonewort |
Chara baltica |
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Bearded stonewort |
Chara canascens |
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Bird's nest stonewort |
Tolypella nidifica |
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Brown alga |
Ascophyllum nodosum ecad mackaii |
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Foxtail stonewort |
Lamprothamnium papulosum |
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Lesser bearded stonewort |
Chara curta |
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[Lichen] |
Caloplaca aractina |
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Matted bryum |
Bryum calophyllum |
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Pear-fruited bryum |
Bryum turbinatum |
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Petalwort |
Petalophyllum ralfsii |
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Sea bryum |
Bryum warneum |
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* Habitat or species also included in another chapter |
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Description of Coastal Habitats and Species
Intertidal Habitats
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Scotland's mudflats support internationally important numbers of wintering wildfowl and waders |
In sheltered estuaries, where fresh water and salty water meet and water movement is slow, mudflats are formed by deposition of organic matter along with fine silt and clay particles. They generally occupy the low intertidal zone above tide or river swept, subtidal channels. Mudflats can be up to several kilometres wide as in the Montrose Basin and the Solway Firth.
Mudflats are characterised by a low diversity of species, It is not surprising, therefore, that there are no Biodiversity Action Plan priority species uniquely associated with this habitat. The habitat's importance is related to the role played by the remarkably great densities of worms, molluscs and crustaceans, all of which provide food for important populations of birds and fish. One of the most noticeable results of this high productivity is the internationally important concentrations of wintering wildfowl and waders, such as wigeon, teal, dunlin and knot. These birds are attracted to both the rich feeding grounds and the relatively sheltered conditions provided by Scotland's firths.
In some sheltered areas of estuaries, and particularly in sea lochs with a paucity of medium grained sand, the priority habitat 'sheltered muddy gravels' is found. In the Sound of Arisaig, where salinity is high and relatively constant, these muddy gravels support an important high diversity assemblage of burrowing animals, as well as other animals attached to pebbles, etc. The Habitat Action Plan for sheltered muddy gravels concentrates on this rarer form of the habitat and its associated species.
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Unattached Egg Wrack (a Brown Alga) Species Action Plan |
box 3.2 |
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The egg wrack, commonly known as 'Crofter's Wig', is a common brown seaweed which grows on sheltered rocky shores all around Britain. A distinctive form, which develops in response to environmental conditions, is unattached and free-living, and is named Ascophyllum nodosum ecad mackaii. This has a very limited distribution, with the main British and world populations confined to extremely sheltered shores in Scottish sea lochs. Threats to populations of the unattached form of egg wrack include road improvements and construction of new roads or causeways, forming small embankments which can isolate the seaweed beds from the sea. The beds are also particularly vulnerable to clean-up operations, or being smothered under rubbish dumped on the foreshore. The common attached form of egg wrack is collected on a small scale in western Scotland for the extraction of valuable chemicals. There is a need to raise awareness amongst collectors so that they know the importance of the distinctive and rare unattached mackaii form. Local authorities also need to be aware of the sites where it occurs because planning decisions can affect conditions suitable for its growth and survival. Construction schemes, such as bridges and causeways, need careful planning to avoid harming beds of 'Crofter's Wig' or maerl beds. Early consideration in the planning stage can often enable a simple engineering solution to preserve the habitat. Where construction has been approved, as in the case of the Skye bridge, careful monitoring is required to establish the effectiveness of mitigation measures. |
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Coastal saltmarsh, or merse as it is known in Scotland, forms the upper vegetated parts of intertidal mudflats in the zone between mean high water of neap tides and the high water of spring tides. Saltmarsh is built up by a community of sea-water tolerant (halophytic) plant species such as glasswort, sea meadow grass, mud rush and narrow club-rush. Even within the narrow sea level band where it is found, saltmarsh exhibits clear zonation according to the frequency of inundation by seawater. At the lowest level, the pioneer glasswort can withstand up to 600 tides per year, while transitional species of the upper marsh can only withstand occasional immersion.
Saltmarsh dominates the Solway coastline. A number of important saltmarsh plants such as rock sea lavender and common cordgrass reach the northern limit of their distributional range in the Solway, making the Solway marshes of particular significance. The saltmarsh vegetation provides food for important populations of wintering geese, particularly the barnacle and dark-bellied brent geese, and breeding areas for wading birds such as redshank.
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Saltmarsh (merse), made up of specialised salt-tolerant plants, supports wintering wildfowl, breeding waders and many species of insects |
Beds of seagrass, such as eel grass, provide important nursery grounds for flat fish in summer, and food for ducks and geese in winter |
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Seagrass beds Habitat Action Plan |
box 3.3 |
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Eel grasses are unusual flowering plants with adaptations to saline habitats. Three species are found in Scotland on shallow sand or muddy sand substrates. The intertidal narrow-leaved eel grass and dwarf eel grass are mostly found in the east coast firths: the Cromarty Firth hosts the largest known stand of dwarf eel grass in the UK. The sublittoral eel grass beds predominantly occur on the west coast. All beds of eel grass are important ecologically for the physical and chemical effects they have on their habitat. The plants and their root systems aid deposition of organic detrital material from the sea water and provide shelter for other fauna and flora, thereby enhancing species diversity. Wintering geese use the beds as an important food source. They are also an important nursery ground for fish. Rarer species often associated with seagrass include two pipefish species (Syngnathus typhie and Entelurus aequoraeus) and a red alga (Polisiphonia harveyi). Eel grasses are at risk from pollution, mobile fishing gear and development. Eel grass is susceptible to a wasting disease which has reduced its densities since the 1930s. The principal objective identified in the Habitat Action Plan for eel grass beds is to assess the extent and quality of the habitat around the UK coast. |
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Only relatively narrow areas of saltmarsh are found in east coast estuaries although the reed beds of the Tay Estuary are the largest continuous stand of this habitat in the UK. These are managed for their economic use, for thatch, in a way which maintains their wildlife value. In Scotland, saltmarsh has special conservation significance wherever there is a complete transition in zonation from the saltmarsh to terrestrial habitats, such as woodland, grassland or dune. Complete ecological transitions are rare in other parts of the UK due to land use for development and agriculture and hence these transitions in Scotland are ecologically very important.
Mudflats and saltmarshes, like other sedimentary intertidal habitats such as soft cliffs and sandy beaches, dissipate wave energy from the sea and thereby reduce the impact of coastal storms on the land. Thus they have a crucial role to play in coastal defence. A mud surface can also be important in absorbing polluting chemicals. In some industrialised estuaries, such as the Firth of Forth, there may be high concentrations of toxic metals, such as copper and lead, locked away in the sediment as a result of many decades of pollution. It is important that great care is taken to avoid releasing these pollutants by disturbing such sediments.
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Saline Lagoons Habitat Action Plan |
box 3.4 |
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Saline lagoons are natural or artificial water bodies partially separated from the sea. Scotland has a large number of these habitats with 139 lagoon sites, including 21 Sites of Special Scientific Interest and two National Nature Reserves. Most are in the Outer Hebrides (59 per cent) and Orkney and Shetland (33 per cent), with the largest lagoons being Loch Bee in South Uist (850 ha) and the Loch of Stenness in Orkney (860 ha). There is a characteristic lagoonal community, including priority species which all have their own Species Action Plans or Statements, such as five species of stonewort and the lagoon sea slug. Substantial progress has been made with implementation of the Saline Lagoons Habitat Action Plan. The Saline Lagoon Working Group (SLWG) is co-ordinating action towards the saline lagoon habitat and associated species action plan objectives. The SLWG proposes to prepare a guide to best practice in the restoration and management of these habitats. The most important proposed future actions and research relate to increasing the profile of saline lagoon issues in all shoreline management planning, maintaining the natural fluctuations in water movements into and out of lagoons, and studying the ecological requirements of lagoonal species. The SLWG will explore opportunities which may arise from managed retreat from coastal erosion to test methods of creation of new saline lagoons. A research project to investigate factors affecting the condition of a site is proposed for the Loch of Stenness, Orkney, which is a candidate Special Area of Conservation (SAC). |
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Sand Dunes and Machair
Towards the mouth of an estuary and on an open coast, the proportion of sand in the sediment increases because the higher wave energy washes away the fine grain particles of mud, which are subsequently deposited in more sheltered areas. On the open coast, mudflats and saltmarshes give way to sandy beaches and sand dune systems.
An essential feature of sand dunes is their dynamic nature. Trends of erosion and of dune building can change within short stretches of coastline and the key conservation action is to allow natural processes, which create, maintain and change dune systems, to function without artificial constraints. In many developed coastal areas, natural systems have already been changed or interrupted due to stabilization by sea defences, recreational use and agricultural land use.
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Types of sand dune found in Scotland |
box 3.5 |
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Sand dunes form where there is a supply of medium grained sand in the intertidal zone and prevailing onshore winds. The critical factor is a sufficiently large area of beach where the surface dries between tides, allowing the sand to be blown inland. The forces of wind, wave and tide can form dunes in many different ways. There are bay dunes between headlands, spit dunes at the mouth of estuaries, such as that of the River Tay, and hindshore dunes where sand is blown inland. Torrs Warren on the Solway Coast is one the largest hindshore dune systems in the UK. There are also climbing dunes where sand is blown onto higher ground and tombolos where a neck of sand is deposited out to an island, for example St. Ninian's Tombolo in Shetland. Dune vegetation is dependent on both the stability of the sand and the time period since deposition. Embryonic or mobile dunes lack vegetation cover altogether, while semi-fixed dunes, as their name implies, are partially stabilized by grass, principally marram grass and more locally lyme grass. Fixed dune grassland generally occurs where there are low dunes or flat sandy terrain, and the vegetation is usually comprised of fescue grasses, eyebrights, lady's bedstraw, and a variety of other species. If this grassland is not maintained by grazing of stock or rabbits, an ecological succession takes place to rough grass, then to dune scrub and finally to afforested dunes. Barry Buddon is a key site for coastal geomorphology, in particular the parabolic dune system which provides a rich and varied habitat for the numerous species of flora and fauna that it sustains. Although part of an MoD Training Area it is effectively managed by MoD for biodiversity. |
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Scotland has a great variety of dunes of all types. Of these, 26 per cent are in the Western Isles and include the best examples of the machair habitat. Culbin Sands on the Moray Firth is the largest afforested dune system in the UK. Juniper forms dune scrub on three sites in Scotland: Morrich More in the Moray Firth, Coul Links, just north of Dornoch, and Invernaver on the north coast. The natterjack toad, which has suffered a substantial decline in numbers and range during the 20th century due to habitat loss, lives in the sand dune habitat on the Solway Coast.
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Natterjack toad numbers and range declined substantially during the 20th century because of loss of suitable dune systems. Happily, they still survive in some areas in south Scotland |
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Machair Habitat Action Plan |
box 3.6 |
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Machair is a specialised agricultural habitat on the sand dunes of the Inner and Outer Hebrides. Machair is more than just a habitat of birds, plants and sandy soil. It is a blend of low-lying coastline, shell sand, the effects of strong wind, the right amount of rain, and, most crucially, the involvement of people with their grazing animals and low input crop rotations. Machair is a delicately balanced ecosystem which is as much dependent on the socio-cultural links with the people who live and croft there as with the physical and biological conditions which support it. The largest machairs occur in Harris, Lewis and the Uists. Machair develops on the landward side of sand dunes; it is a wind built sand surface with lime rich soil (pH>7), stabilised by a high diversity sward of short grasses and herbs such as yarrow, lady's bedstraw and ribwort plantain. The densities of breeding wading birds - mainly redshank, dunlin, ringed plover and oystercatcher - on the machairs of the Uists and Tiree are unsurpassed in Europe. The breeding wildfowl of the machair lochs includes large numbers of native greylag geese. Two of the most important machair birds, the corncrake and the corn bunting, both with Species Action Plans, are more often heard than seen. Traditional farming practices add to the important contribution which machair makes to the landscape of the Western Isles. The Machair Habitat Action Plan is largely directed at encouraging the adoption and uptake of farming support mechanisms, e.g. agri-environment schemes, to enable good management and preferably enhancement. Better understanding of the appropriate grazing management is required as well as demonstrations of good practice. The threat of coastal erosion needs to be evaluated. The important role of farmers and crofters is recognised in actions which seek to understand the socio-economic aspects of machair and hence to enable better support for those who live and work on the habitat. |
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The unique sandy plain of the machair in the Inner and Outer Hebrides supports a wide range of flowers and large numbers of breeding birds |
The orchid, Dactylorhiza majalis scotica, is found only on the machair of North Uist |
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Corncrake Species Action Plan |
box 3.7 |
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The associated Corncrake Species Action Plan seeks to address the loss of tall vegetation throughout the breeding season and advocates changes in grass management and cutting. The actions promote the uptake of 'corncrake friendly' mowing schemes to reduce damage to adults and young. Research on the impact of mowing and predation is highlighted along with proper monitoring of the effectiveness of management schemes, especially that incorporating the agri-environment measures. The promotion of 'green tourism' based on corncrakes is also put forward as a consideration. |
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Coastal vegetated shingle structures are found on high energy coasts in the form of shingle spits, shingle bars, beaches and barrier islands. Like sand dunes they are naturally dynamic and require a constant supply of sediment for their maintenance. Narrow strips of vegetated shingle support strandline communities. Many of these shingle structures are patchy and very small in area; it is, therefore, difficult to estimate their overall extent and distribution. However, it is possible that about half of the vegetated shingle in Scotland is found in Argyll and in Spey Bay on the south side of the Moray Firth.
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Corncrakes have declined throughout western Europe with the loss of traditional hayfields. Tall vegetation in early summer and late cutting of hay are key to their survival |
Scotland's cliffs provide nest sites for internationally significant numbers of seabirds |
Rocky Coast Habitats
High cliffs are mostly restricted to the north and west of Scotland, particularly in the Outer Hebrides (20 per cent by length) and Northern Isles (23 per cent). The vertical or steeply sloping angles of cliffs support only a few vascular plants. Scots lovage and thrift can survive on ledges or crevices where a break in slope allows some soil to accumulate. Here also are the breeding sites for thousands of seabirds including gulls, terns, fulmars and guillemots. Soft cliffs of shale, or unconsolidated boulder clay, slope at much shallower angles, as on the coasts of Fife and Skye. They are subject to erosion and land slip; vegetation may be limited to pioneer communities on freshly exposed faces, whereas grassland, scrub or woodland can develop on more stable slopes. Wet flush vegetation is common where groundwater seeps from the cliff face.
A specialised maritime grassland plant community forms on cliff top land exposed to sea spray. It is characterised by short turf species such as sea plantain, carnation grass, vernal squill, and red fescue. In Scotland, this habitat is also almost entirely found in the Northern (79 per cent) and Western Isles (14 per cent).
Tidal Rapids
Tidal rapids are high energy environments often resulting from a constriction in the coastline. They characteristically occur at the entrance to sea lochs where the tidal flow is funnelled through a narrow or shallow channel. Strong tidal streams give rise to characteristic marine communities, nourished by a constantly renewed food source brought in on each tidal cycle. Scotland's fjordic sea lochs, such as Loch Alsh and Kyle Rhea, have some of the strongest tidal streams in the UK. In the shallower, fjordic sea lochs characteristic of the Western Isles, such as Loch Maddy in North Uist, with systems of islands linked by shallow basins, tidal rapids between the basins may extend into the intertidal zone, allowing rare opportunities for easy access to complex and diverse sea bed communities.
The marine life associated with tidal rapids must be strongly attached to the sea bed to withstand the forces of the constantly sweeping tidal currents. It typically includes a colourful mix of soft corals, sea firs (hydroids), sea mats (bryozoans), large sponges, anemones, mussels and, where the current slackens, dense beds of brittlestars.
Trends of Change and Threats to Coastal Habitats
The tendency for human populations to locate themselves on the coast and to develop it, coupled with the powerful consequences of natural coastal processes, makes the conservation of coastal habitats a complex process. Sea level rise as a result of global warming is predicted to be of the order of 15-30 cm by 2050, varying geographically. Climate change is also likely to increase both storm intensity and storm frequency, which might increase rates of coastal erosion in Scotland. These are scenarios of change, meaning that the future for Scotland's coasts is, to some extent, uncertain.
The gradual lifting of the land in Scotland due to ice unloading is being overtaken by acceleration of sea level rise. As a result, cases of coastal erosion damage and demand for improved coastal defences are increasing. However, if the response to rising sea level is merely directed at improvements in coastal defences, there will undoubtedly be a major loss of valuable intertidal habitat. The intertidal zone will become progressively narrower, eroded by rising sea level and ever larger coastal defences - a phenomenon known as 'coastal squeeze'. Managed re-alignment is a technique for dealing with sea level rise. It involves not only moving and remodelling actively maintained sea defences, but also establishing intertidal habitats that reduce the power of waves between the open sea and the new defences. In this way, both effective flood defence and benefits to coastal biodiversity are maximised.
In many estuaries, mudflats have been greatly reduced in extent by centuries of landclaim for agriculture and other development. In recent years the main developmental growth sectors affecting coasts have been the North Sea oil and gas service industry on the east coast and fish farming on the west coast. Increasing leisure and transport have provided more access and have led to more coastal recreation. This increased use has brought greater pressures on coastal habitats from landclaim for development, disturbance of wildlife, and both diffuse and point-source pollution. Although damage increases slowly, cumulative impacts can lead to significant losses of natural habitat over decades. All habitat types, with the exception of cliffs, have declined in the recent past, but sand dunes, saltmarshes and intertidal mudflats have been most affected.
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Natural and anthropogenic factors affecting coastal habitats |
box 3.8 |
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Summary of Chief Objectives and Proposed Actions for Coastal Habitats
Action plans recognise that a great deal of coastal habitat has been lost in recent decades and that the current pressures, both natural and anthropogenic, are difficult to reduce. All primary objectives are focused on maintaining the extent, quality and distribution of the habitats. In general, targets for habitat creation or restoration are relatively modest, but there is a strong emphasis on maintaining or restoring the natural functioning of coastal habitats and allowing natural coastal processes to occur unhindered wherever possible. This approach includes keeping sand dunes in a dynamic condition as well as using natural habitats to provide the normal means of coastal defence against erosion and changing sea level.
Integrated Coastal Zone Management (ICZM) is an increasingly used approach to the issue of managing the wide variety of often conflicting interests and land uses which are found along coastlines. It is based on the development of a management strategy which takes account of all the interests by forming a voluntary partnership in which all stakeholders are represented. It is dependent on the commitment of all sectors to work together to compile data, to agree issues and to resolve problems of conflict. It is likely that the final management strategy from this process will include a range of actions for all members of a partnership as well as a system of zoning the coastal area for different activities. In Scotland, the Focus on Firths projects have initiated ICZM programmes for six large firths: Clyde, Cromarty, Forth, Moray, Solway and Tay. All these firths support priority species and habitats and ICZM aims to assist in meeting the objectives for conserving and enhancing their biodiversity, despite the intense development and multi-user pressures on the sites. The Focus on Firths projects have shown that there is widespread cross-sectoral recognition of the need to protect coastal wildlife. Management strategies are seeking to put in place a sustainable approach to the use of firths which will take account of the need to conserve and enhance coastal habitats and the species which live in them.
The ICZM approach is being adopted for the management of Scottish SACs, which are among the most important coastal sites in Europe. The aim is to ensure that the habitats and their typical species are managed in a way which ensures their maintenance in perpetuity.
Natural coastal habitats provide the most effective protection for the land from the forces of erosion created by the sea. The cost of improved coastal defences to mitigate the impact of sea level rise would be prohibitive if current predictions are correct. Shoreline Management Plans (SMPs) are increasingly used strategically to plan for rising sea level. Using coastal process data, SMPs identify sections of the coast which are most at risk, and the most appropriate coastal defence techniques for each area. Where possible the use of 'hard engineering' (built) sea defences is avoided and natural processes (soft engineering) are allowed to continue. The landward progression of natural coastal habitats would be encouraged so as to protect developments further inland.
Recognition of the value of natural coastal dynamics, and the role of mudflat, saltmarsh and sand dune in coastal protection, will help to ensure that SMPs incorporate the principles of biodiversity conservation. In some cases the breaching of existing sea defences may be allowed so as to facilitate the creation of new coastal habitats. This technique, known as 'managed retreat', is likely to be the most cost-effective solution to rising sea level for many coastlines and could reverse the trend of intertidal habitat loss. The ICZM approach ensures that all interest groups are able to take part in the decision-making process, and that a broad consensus emerges for the management of Scotland's coastline, its habitats and the species that live there.
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