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Introduction
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Even species like these guillemots on St Kilda are not isolated from the impacts of man's activities |
William Beebe (1877-1962), a pioneer of underwater science, wrote "The moment one is submerged, the reality of the absolute apartness of this place is apparent. In this kingdom most of the plants are animals, the fish are friends, colours are unearthly in their shift and delicacy; here miracles become marvels, and marvels recurring wonders". These words about the oceans that William Beebe explored in the first half of the last century paint a picture that is a fitting description of the seas around Scotland. Descriptions of marine wildlife and the seabed were generally based on what could be brought to the surface in dredges, grabs and nets. The renowned naturalist Edward Forbes, who held the Chair of Natural History in Edinburgh in 1854, relied on these techniques in his explorations of the Irish Sea and coastal waters around Scotland. These led to the first dredging beyond the Scottish continental shelf, proving that life did exist at great depths in the oceans
Today, discovery and description of the marine environment are inevitably linked to questions about the impact of human activity; about how marine resources might be exploited sustainably; and about how to maintain the quality of the environment and the abundance of its species. More and more people are now discovering for themselves the wealth of marine life off Scotland's shores through the availability of scuba equipment and underwater videos. For the vast majority of people, however, the marine environment remains inaccessible and unknown. For too long it has been considered to be resilient to human impacts. The inclusion of marine wildlife in the UK Biodiversity Action Plan and in Local Biodiversity Action Plans is therefore essential, not only because of the major contribution of the seas to global biodiversity, but also because the plans provide a much needed focus for marine conservation action in Scotland. Many people in Scotland live near the coast and depend on the sea for their livelihood or recreation.
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The Seas: |
box 2.1 |
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Habitat Action Plans |
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Lophelia pertusa reefs |
Maerl beds |
Maritime cliff and slope* |
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Modiolus modiolus beds |
Mud habitats in deep water |
Sabellaria alveolata reefs |
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Sabellaria spinulosa reefs |
Serpulid reefs |
Sublittoral sands and gravels |
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Species Action Plans: Vertebrate Animals |
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Atlantic white-sided dolphin2 |
Lagenorhyncus acutus |
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Basking shark |
Cetorhinus maximus |
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Blue whale1 |
Balaenoptera musculus |
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Bottlenose dolphin2 |
Tursiops truncatus |
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Common dolphin2 |
Delphinus delphis |
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Common skate |
Raja batis |
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Cuvier's beaked whale3 |
Ziphius cavirostris |
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Fin whale1 |
Balaenoptera physalus |
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Green turtle4 |
Chelonia mydas |
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Harbour porpoise |
Phocoena phocoena |
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Humpback whale1 |
Megaptera novaeangliae |
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Kemp's ridley turtle4 |
Lepidochelys kempii |
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Killer whale3 |
Orcinus orca |
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Leatherback turtle4 |
Dermochelys coriacea |
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Loggerhead turtle4 |
Caretta caretta |
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Long-finned pilot whale3 |
Globicephala melas |
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Minke whale1 |
Balaenoptera acutorostrata |
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Northern bottlenose whale3 |
Hyperoodon ampullatus |
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Northern right whale1 |
Eubalaena glacialis |
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Risso's dolphin2 |
Grampus griseus |
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Sei whale1 |
Balaenoptera borealis |
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Sowerby's beaked whale3 |
Mesoplodun bidens |
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Sperm whale3 |
Physeter catodon (P. macrocephalus) |
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Striped dolphin2 |
Stenella coeruleoalba |
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True's beaked whale3 |
Mesoplodon mirus |
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White-beaked dolphin2 |
Lagenorhyncus albirostris |
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Commercial Marine Fish |
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Deep-water Fish |
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Species Action Plans: Invertebrate Animals |
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[Fan shell] |
Atrina fragilis |
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Native oyster |
Ostrea edulis |
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Northern hatchett shell |
Thyasira gouldi |
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Sea-fan anemone |
Amphianthus dohrnii |
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[Sea pen] |
Funiculina quadrangularis |
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[Sea squirt] |
Styela gelatinosa |
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1 Six species grouped together in the Baleen Whales Grouped Species Action Plan. |
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2 Six species grouped together in the Small Dolphins Grouped Species Action Plan. |
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3 Seven species grouped together in the Toothed Whales (other than Small Dolphins) Grouped Species Action Plan. |
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4 Four of the five species included in the Marine Turtles Grouped Species Action Plan. |
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* Implies that this species or habitat is also included in another chapter. |
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The seas are unique in being an open environment, where planktonic plants, eggs and larvae of many animals, as well as swimming adult animals, can be transported over large distances by tidal currents. Barriers to species' movements are few, but include poor water circulation and reduced salinity within some sea lochs. Sea bed type, whether hard rock or soft sediment, is the major determinant of the local species composition on the sea floor. The exact mix of species at any one site depends on many factors including past history, environmental conditions and biological interactions between different species as well as human influences such as oil pollution. Whereas on land the climax community at lower altitudes is normally forest, in the seas a much wider range of climax communities occurs, some dominated by plants, others by sessile animals. The huge range of niches available from the intertidal zone down to the greatest ocean depths is largely responsible for the large biodiversity of the seas around Scotland.
Description of Habitats in Scotland's Seas
The sea and seabed around the shores of Scotland support a tremendous variety and richness of wildlife. One reason is the geographic position of the country. The North Atlantic Drift (Gulf Stream) brings warm waters to the west coast of Scotland. Cold sub-Arctic waters reach down to the Northern Isles. The range of exposures to currents and wave action, and the varied geology, add further dimensions to the complexity of Scotland's marine environment. This is most obvious at the coast where dramatic differences occur within just a kilometre or two as one moves from sheltered sea lochs to exposed cliffs and beach. This variety also extends to the underwater scenery and to the plants and animals that are dependent upon it.
Underwater Cliff and Slopes
The rocks forming the land continue underwater. Cliffs on land become submarine walls, blocks eroded from the land become boulder fields, and gently sloping rocky shores become terraces and reefs. The rock surfaces are frequently colonised by kelp, brown seaweeds forming the underwater forests which fringe many parts of the Scottish coast. All manner of wildlife shelter and thrive there: firmly attached sea anemones, sponges and sea squirts, as well as more mobile species like brittlestars, sea urchins and fish. It is this variety, combined with clear water, which draws sport divers from all over the UK and from further afield, contributing significantly to Scotland's tourist income.
One of the criteria used to identify priority marine habitats is the presence of 'keystone species' which support a characteristic community of other species. Examples of keystone species forming habitats are kelp forests and horse mussel reefs. These host fish and other creatures that depend upon the keystone species for shelter and food.
Offshore and Inshore Sediments
Much of the seabed, both offshore and inshore, is composed of soft sediment, but it is not the featureless expanse that is sometimes imagined. Sand, shell material and mud may be worked into banks, waves and furrows, while smaller features are created by the associated wildlife. Burrows, mounds and tracks across the surface of the seabed give clues about what lives in and around the sediment. Although generally out of sight, a wealth of small life forms live in the sediment and their diversity provides a good indication of the health of the environment.
Sands and gravels are common in inshore areas. Many are important nursery grounds
and hence vital habitats for commercially important fish and shellfish. The
fan shell is a non-commercial species found in shallow waters in areas of muddy
sand or fine gravel. Although thought to be widespread, it is rarely encountered.
The Species Action Plan for the fan shell recognises the need to learn more
about its distribution and ecological requirements. Although this can be done
by research institutes and universities, there is also scope for others to get
involved. Proposed actions include encouraging fishermen and divers to participate
in a national reporting scheme and promoting a 'look but don't touch' code of
conduct for divers.
Oceanic Seas
The edge of the continental shelf is one of the most distinctive underwater features off the west and north west coasts of Scotland. Indeed, the majority of the UK controlled waters deeper than 200 m lies in Scottish waters. The shelf slope extends from the shelf-break, at around 200 m, to between 1,000 m and 2,000 m depth. The whole area has enhanced productivity with rich populations of plankton and is an important feeding ground for large shoals of fish, flocks of oceanic birds and cetaceans. Several commercially exploited fish including mackerel and blue ling spawn at the shelf-break, and whales travel along this feature during their seasonal migrations.
Deep-water muddy sediments occupy the seabed below 200 m. These support a very high diversity of small burrowing animals. Many of these remain to be adequately described by taxonomists and hence contribute to the uncertainty about the number of invertebrate animals stated in Box 1.1.
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Deep-water fish Species Action Plan |
box 2.2 |
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The deep sea, below 1,000 m, supports a great diversity of life in the water column as well as near, on and in the seabed. Some deep-water fish species are commercially fished and this can be in depths of as little as 400 m. The Atlantic deep-water bottom trawl fishery started in the late 1960s when Eastern Bloc countries began to exploit roundnose grenadier in international waters west of Rockall and on the Hatton Bank. The range and scale of the fishery has increased substantially since then and has moved closer to the shelf edge in waters within coastal state jurisdiction. The upper slope fisheries (c 400-800 m) are dominated by France and the UK and target blue ling and monkfish. Mid-slope fisheries (c 800-1,200 m) are mainly French vessels seeking blue ling and roundnose grenadier. France also dominates the deep slope fishery (1,200-1,700 m) where orange roughy is the target. Long line fisheries are also operated in this range of depths, mainly by Spanish and UK registered boats landing their catches in Spain and Norway. Hake is the main species for the Spanish market and blue ling, ling and tusk are favoured by Norway. There is, however, a lack of information on the biology of these and other deep-water fishes and no catch quotas are currently in force. Because of this, the Species Action Plan for deep-water fish calls for research into likely sustainable catch levels as a matter of urgency, as well as for investigations into the importance of deep-water fish in the food chains of other marine organisms. Technical measures to minimise damage to non-target and juvenile deep-water fish are also urgently needed. Achieving this requires action to be taken at the international level through bodies such as the International Council for the Exploration of the Sea (ICES) and the EU, as well as by individual fishermen. |
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Trends of Change and Threats
The bounty of the sea was the basis for the thriving fisheries in earlier centuries. Today the economic importance of the seas continues, not only for fishing but also for other interests such as oil and mineral extraction, shipping, tourism and recreation. The sea's plants and animals are also a promising source of new drugs and pharmaceuticals. Conservation of marine biodiversity therefore requires the concerted and combined action of many people.
The sea has been described as the last great wilderness but it too has been affected by human activity. Close to shore, declining water quality due to pollutants, land claim, dredging, and fisheries are some of the pressures on marine habitats and wildlife. The widespread effects on the shellfish industry of Paralytic Shellfish Poisoning, caused by natural toxins from microscopic algae but almost certainly exacerbated by pollution of various sorts, show just how devastating such impacts can be both on biodiversity and the economy. Further offshore there are threats from fishing, shipping and the oil and gas industries. In some cases activities also have wider implications. For example, some types of fishing not only deplete the target species but are capable of removing a source of food for other wildlife and can damage non-target species, the so-called 'by-catch'.
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Marine turtles Species Action Plan |
box 2.3 |
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Seven species of marine turtle have been recorded in UK waters and although most of these are believed to arrive accidentally, sightings of the leatherback turtle are almost certainly the result of a deliberate migratory movement. No species of turtle nests in the UK but many of the UK Overseas Territories have important nesting populations. Threats to these species include harvesting of eggs and adults for meat, damage to nesting sites, and incidental capture and drowning in fishing gear. Various initiatives are underway to contribute to international measures for the conservation of these animals. They include an Information and Advisory Note (see 'Further Reading', chapter 10) prepared by Scottish Natural Heritage on dealing with live, stranded or entangled marine turtles, and actions directed at improving water quality, especially to reduce marine debris which can be ingested by turtles. All water users can play a part but there will also be a need for greater control of land-based pollution which gets carried out to sea. |
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Summary of Main Objectives and Proposed Actions
For marine habitats, most of the objectives are concerned with maintaining their extent and quality. There is also much to learn, so both research and raising awareness through education programmes are other essential components of these plans.
Many of the plans include measures directed at fishing activity and in the long term will benefit fisheries as well as the conservation of marine biodiversity. No-take zones are being used increasingly in other parts of the world to enhance fisheries by the 'spill over' effect into adjacent areas; limits on areas open to mobile gear which damage the habitat and species can improve conditions for creel fishermen; and maintenance of high water quality standards in sheltered inlets and bays will benefit shellfish cultivation. 'Several Orders' and 'Regulatory Orders', used for the management of shellfish fisheries, can give local control and responsibility for management of stocks to those directly involved in the fishery; zoning schemes can be used to control and direct activities.
Biodiversity conservation can also be part of good management practice, as in the operation of commercial fisheries. If the aim is to have viable, stable and sustainable commercial fisheries, the actions being advocated for a number of the priority species and habitats, as well as those which are specific to commercial fisheries, will be of benefit.
For the inshore sediments, the required conservation actions include research into the effects of fishing gear and aquaculture on the habitats and associated species in order to avoid or reduce damage. Protected areas, with different management zones, such as undisturbed areas or 'no-take zones', can also help to achieve this. There are currently very few examples of the latter, but they may exist in inaccessible areas or sites under the control of the Ministry of Defence (MoD), for example. Other actions include determining the extent of unmodified examples of these habitats and ensuring that the best examples are protected from the adverse effects of activities that disturb the seabed, such as dredging for navigational purposes, trawling and aggregate extraction. Key players include planners, port and harbour authorities and the Crown Estate Commission.
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A marine worm: Serpulid Reefs Habitat Action Plan |
box 2.4 |
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Serpula vermicularis is a marine worm which secretes a hard limy tube around itself. Exceptionally, it aggregates into reefs covering areas up to 1 m across. The reef form appears to be very rare and, in the UK, has only been reported from two Argyll sea lochs. Those previously reported from Loch Sween are no longer thought to exist; the extent of reefs in Loch Creran has declined over the last 100 years. Despite this, the Loch Creran populations are thought to form the best reefs of this type in the world and the three dimensional structure of the reef provides crevices in which a host of other animals can live. It is not known why serpulid reefs form at so few sites; the factors which might cause loss or decline are unclear. The action plan therefore advocates research into factors affecting the settlement, growth, maintenance and ecology of the reefs and associated species. This will involve academic institutes but other parties also need to take action. There is a very significant role for local authorities and for those undertaking development schemes on the shores of Loch Creran because construction schemes may obstruct or alter the water flow to the serpulid reefs. Being alert to the implications and, if necessary, altering schemes to avoid impacts, will be an important action that could be taken. |
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Reefs of the cold water coral Lophelia pertusa can be as rich in biodiversity terms as some tropical coral reefs |
Research is vital to determine the status and conditions needed for survival of the species in question; monitoring is necessary to give early warning of problems (as for example the Species Action Plan for the northern hatchet shell). Although perhaps seen as the remit of academic institutions, others such as those with an enforcement or management role could also take part in such work.
Actions need to be taken by a considerable range of people and organisations for the successful conservation of marine biodiversity. These actions include day-to-day tasks together with more wide-ranging or occasional opportunities to influence matters at a political level. What is also clear is that taking such actions can bring benefits beyond those for wildlife. Marine wildlife tourism, an activity which can thrive in areas that support wildlife, is one example. In 1996, the total revenues generated by this activity in the Highlands and Islands alone was estimated to be in the order of £57 million. Socio-economic benefits include bringing economic activity and additional revenue to the more fragile, peripheral economies.
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Cold Water Coral: Lophelia pertusa Reefs Habitat Action Plan |
box 2.5 |
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In temperate waters hard corals are usually solitary but the cold water coral, Lophelia pertusa, is an exception. Small patches of Lophelia have been reported from waters to the west and north-west of Scotland and, although typically found in water depths between 200 m and 400 m, it may grow as deep as 3,000 m. Colonies of Lophelia can form substantial reefs growing several metres clear of the seabed. In a recent survey of existing literature, more than 800 different species of plants and animals have been recorded living amongst live and dead coral. This makes these cold water reefs as rich in biodiversity terms as some tropical coral reefs. Deep-sea bottom trawling can break coral colonies. The Habitat Action Plan calls for provision of information and advice to fisheries organisations, fishermen and fisheries policy makers so as to improve the monitoring of fishing activity. The plan also advises that key sites should be protected; this includes the designation of protected areas for Lophelia. Although geographically remote, human activity is having an impact on these coral reefs. The offshore oil and gas industries pose a threat to the reefs both from pollution and from sedimentation of drilling muds, although ironically deepwater oil rigs may also prove to be a valuable habitat for colonising groups of this cold water coral. Both industries have an important role in securing the conservation of these remarkably species-rich reefs. The action plan calls for a review of the procedures for block licensing for oil exploration to take account of the conservation requirements of this species, and for a policy which avoids siting oil drilling operations where the coral is known to occur. |
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Bottlenose dolphin Species Action Plan |
box 2.6 |
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An example of the potential economic benefits from nature conservation can be seen in the Moray Firth. The area has become well known for its resident population of bottlenose dolphin. Boat tours are the focus of a tourism activity which is developing in the area because of the dolphins. More than 30,000 people participated in these trips in 1996 and a survey revealed that of the tourist respondents, 28 per cent said the dolphins had been the sole or principal reason for visiting the area. An accreditation scheme - The Dolphin Space Programme - has been introduced to prevent harassment and disturbance of the dolphins so as to help to protect the long term viability of the Moray Firth population while allowing people to enjoy watching the dolphins. |
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Careful provision of tourist opportunities for watching the bottlenose dolphins in the inner Moray Firth generated revenues estimated at £57 million in 1996 |
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Maerl Beds Habitat Action Plan |
box 2.7 |
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Maerl is a collective term for several species of red seaweed which form hard 'calcified' outer casings and grow as nodules on the sea bed. Over long periods the dead skeletons can accumulate into deep deposits covered by a pink layer of living maerl. These maerl beds are an important habitat for a wide variety of marine plants and animals which live amongst the branches or burrow into the coarse gravel of dead maerl. Over 1,700 animal species and 300 seaweed species have been recorded from European Maerl beds. Maerl beds are particularly well developed around the Scottish islands and in the narrow mouths of sea lochs around Orkney. In many areas they have declined substantially, probably due to a combination of physical damage to the delicate skeletons and from pollution. Maerl is of commercial value as a soil conditioner on acidic ground, as an animal food additive, for the filtration of acid drinking water, and in pharmaceutical and cosmetic products. The Habitat Action Plan encourages those operating and controlling the commercial extraction of maerl to ensure that it is done in a way which maintains the living maerl and the associated species. Maerl's slow growth rate is likely to compromise its ability to recover from disturbances of various kinds. Potential damage from mobile fishing equipment and operations such as scallop dredging can be addressed through increased awareness amongst fishing organisations and better policies to protect vulnerable sites. The building of barrages, causeways, bridges and energy schemes are potential blockages to water flow, threatening maerl beds, particularly in sea lochs and between islands. Careful planning is essential to avoid this. Pollution from eutrophication, which causes smothering of the maerl from excess growth of other seaweeds, requires action from the Scottish Environment Protection Agency (SEPA), which controls and manages discharges of sewage and other fertilisers. The use of chemicals in some fish farms needs careful control to avoid the risk of these spreading into sensitive areas in the marine environment, including maerl beds. Research is required to understand the biology of maerl better, including the species that depend on it, and the ability of the habitat to recover from disturbance. Information is required to ensure better understanding of the importance and vulnerability of maerl by those who use our coasts or control coastal activities. |
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Seaweed can be damaged by inappropriate harvesting and by pollution from sewage and fertilisers. Kelp, as shown here, provides an important habitat for marine biodiversity |
The involvement of local communities in conserving marine biodiversity should be encouraged and can make a real difference. In Fair Isle, for example, the residents are developing a zoning scheme to manage the waters around the island. This will not only ensure that they can continue to earn a living from the sea but it will also secure a future for the marine wildlife which thrives in these waters.
The European Union's Habitats Directive requires the designation of important marine sites as Special Areas of Conservation (SACs); similarly the EU's Birds Directive requires the designation of the most important marine areas for birds as Special Protection Areas (SPAs). This action will bring a focus for activity in these areas and enable local communities to understand the conservation objectives. The SACs will also enable the different economic interests to be managed in a way that supports the diversity of wildlife that occurs within these marine areas.
It is important to be clear that it is not only those who live near or work in the marine environment who need to help with the conservation of marine biodiversity. Decisions and actions affecting land areas can ultimately impact our coastal waters and beyond, as can matters decided by international bodies. The action plans provide guidance on how all these groups can make a difference.
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