Publication - Impact assessment

Planning Scotland's Seas: 2013 - Possible Nature Conservation Marine Protected Areas Consultation Overview - Strategic Environmental Assessment Report

Published: 19 Aug 2013
Part of:
Marine and fisheries

This report summarises the findings from a strategic environmental assessment (SEA) of the possible Marine Protected Areas (pMPAs).

110 page PDF

3.3 MB

110 page PDF

3.3 MB

Planning Scotland's Seas: 2013 - Possible Nature Conservation Marine Protected Areas Consultation Overview - Strategic Environmental Assessment Report
5.0 Environmental Baseline

110 page PDF

3.3 MB

5.0 Environmental Baseline

5.0.1 This section of the Environmental Report describes the character of the environment which may be affected by the possible MPAs. The focus of this baseline information is therefore on biodiversity, geodiversity, the ecological/environmental status of water bodies, and climatic factors.

5.0.2 Scotland's location at the edge of the continental shelf means that it is subject to both subpolar and subtropical influences. The North Atlantic current brings warm water from the Gulf of Mexico to the west coast of Scotland. These warm waters mix with cooler polar waters that are rich in nutrients.

5.0.3 Scotland's coastline is over 18,000 km long, and very varied in nature. There are over 900 islands, including the major archipelagos of Shetland, Orkney and the Outer Hebrides. [13]

5.1 Biodiversity, flora and fauna

5.1.1 Scotland's marine environment supports a diverse complex of different habitats, which in their turn support a wide range of marine plants and animals. This diversity owes much to the factors described in paragraphs 5.0.2 and 5.0.3. Current estimates suggest there are around 6,500 species of animals and plants (excluding microbial flora and seabirds) in Scotland's seas (Scotland's Marine Atlas, 2011).

Key Marine Habitats

5.1.2 The seabed is a critical component of marine ecosystems. Six broad habitat types occur in Scottish waters ( Figure 9): intertidal rock, intertidal sediment, subtidal rock, shallow subtidal sediments, shelf subtidal sediments and deep-sea habitats. Figure 10 illustrates the locations of these habitats relative to the shoreline. Overall, mud, sand and coarse sediment are found in the North Sea, to the west of the Hebrides and in the north of Scotland. The seabed in the far west and north of Scotland is characterised by mud and fine clay, with coarser sediments in shallower water and on banks and seamounts [14] . Details of these habitats are provided in the following paragraphs [15] .

5.1.3 Intertidal rock comprises approximately 48% of the Scottish coastline. Large stretches of the west coast and Northern Isles are predominantly rocky, as are the Solway Firth and the Firth of Forth, whereas on the east coast intertidal rock is much more patchy and interspersed by large stretches of sandy and muddy coastline. This habitat, which includes bedrock, boulders and cobbles, is affected by a number of physical factors ( e.g. wave exposure, salinity, temperature and tides).

5.1.4 The various animals and plants found on rocky shores are adapted to survive the stresses imposed by regular immersion and emersion in sea water and the associated fluctuations in temperature and salinity caused by exposure to the sun and rain at low tide. The upper regions of many rocky shores are relatively species-poor, particularly on exposed coasts, but areas nearer to the bottom of the shore can be very species-rich. Rocky shores are popular resting and foraging places for many animals ( e.g. harbour and grey seals, otter and various wading birds).

5.1.5 Intertidal sediments comprise around 50% of the Scottish coastline and include mobile shingle and gravel, sand and mud or combinations of these (including sandflats and mudflats), and saltmarsh in the upper shores. Intertidal sediments predominate on the west coast and in estuaries such as the Solway, Dornoch and Cromarty Firths and the Firths of Forth and Tay.

5.1.6 Intertidal habitats support communities that are tolerant of exposure to air and variable temperatures and salinities, particularly the mudflats and sandflats found in estuaries. The more mobile sediments, e.g. relatively coarse-grained sand, support fewer species of animals, whereas less mobile sediments (such as muddy sands) are more species-rich, supporting communities of amphipods, polychaetes and bivalve molluscs. Mudflats, which are found in the most sheltered areas, are finer (silt and clay) and have a high organic content. Intertidal sediments support such features as seagrass beds, blue mussel beds, and native oysters. Mudflats in particular provide habitat for many juvenile fish and for wintering waders and wildfowl.

5.1.7 Subtidal rock is extensive on the west coast and around Shetland, but is only present in isolated pockets on the east coast. Subtidal rock habitats consist of bedrock, boulders and cobbles occurring below low water mark and the communities found in these areas are affected by the availability of light. Shallow areas are typically dominated by seaweeds; communities in deeper areas comprise exclusively marine animals. Subtidal rock supports such features as Northern sea fan and sponge communities; white cluster anemone; pink sea fingers; European spiny lobster; tide-swept algal communities; and biogenic reefs.

5.1.8 Inshore subtidal and shelf sediments cover an extensive area of the seabed, all around the Scottish coast. Inshore subtidal sediments include shingle, gravel, sand and mud extending to the depth at which there is no effect from waves, typically around 50-70m. The shelf sediments extend to around 200m depth.

5.1.9 Inshore subtidal and shelf sediments support such features as burrowing sea anemone; northern feather star; fan mussel; heart cockle; ocean qhahog; burrowed mud; maerl beds; maerl or coarse shell gravel with burrowing sea cucumbers; inshore deep mud with burrowing heart urchins; shallow tide-swept coarse sands with burrowing bivalves; seagrass beds; and low or variable salinity habitats.

5.1.10 Deep sea habitats are those occurring beyond the continental shelf break at depths typically greater than around 200m. Knowledge of these habitats is limited but is increasing. They are found almost entirely to the north and west of Scotland, and comprise cold water coral reefs, coral carbonate mounds, submarine canyons, sea mounts and deep sea sediments. [16] They support such features as seamount communities; carbonate mound communities; coral gardens; deep sea sponge aggregations; offshore deep sea muds; and cold-water coral reefs.

Mobile Species

5.1.11 Scotland's marine environment also supports a wide range of mobile species. These include:

  • seals (grey and common or harbour)
  • cetaceans. Twenty-three species have been recorded in Scottish waters over the last 25 years. Of these, 11 are regularly sighted.
  • birds, both breeding seabirds and overwintering waterbirds
  • marine turtles
  • sharks and rays, including basking shark and common skate
  • commercial fish and shellfish

Protected Habitats and Species

5.1.12 The importance of Scotland's marine ecosystems is reflected in the range of designations which protect them at the international, UK and Scottish levels. The range of habitats protected includes estuaries; lagoons; large shallow inlets and bays, mudflats and sandflats; reefs; sandbanks; submarine structures; and sea caves. A wide range of species is protected, including breeding seabirds, overwintering waterbirds, fish and seals, amongst others.

5.1.13 In 2013, there were:

  • 85 Special Protection Areas ( SPAs) with marine associations, affording protection to bird species dependent on the marine environment. Thirty-one of the existing seabird breeding colony SPAs have been extended into the marine environment to include the adjacent waters.
  • 40 marine Special Areas of Conservation ( SAC), and seven candidate SACs.
  • 188 Sites of Special Scientific Interest ( SSSI) with marine associations / components, of which 61 overlap with the intertidal environment. The remainder have been designated for bird interests associated with the marine environment. An example of the habitats and species protected at the national level (through SSSI designation) is provided in Table 6.

Figure 9. Modelled distribution of broad habitats in Scotland's marine environment [17]

Figure 9 Modelled distribution of broad habitats in Scotland's marine environment

Figure 10. A generic cross-section of the seabed from the coast to deep waters offshore [18]

Figure 10 A generic cross-section of the seabed from the coast to deep waters offshore

5.1.14 The evolving MPA network in Scotland's seas builds on the existing network of protected areas ( Figure 11), which includes Special Areas of Conservation ( SACs); Special Protection Areas ( SPAs); Sites of Special Scientific Interest ( SSSIs), and fisheries management areas. More information on these other designations and sites is provided in Marine Scotland's report to the Scottish Parliament [7] .

Table 6. Marine notified habitats and species features of SSSIs

Habitats Species
Eel grass bed Brackish water cockle ( Cerastoderma lamarki)
Mudflats Egg wrack ( Ascophyllum nodosum ecad mackaii)
Rocky shore Common seal ( Phoca vitulina)
Saline lagoon Grey seal ( Halichoerus grypus)
Sandflats Stonewort ( Lamprothamnium papulosum)
Sea caves Vascular plant assemblage [covers eel grass communities in some sites]
Tidal rapids

Priority Marine Features

5.1.15 SNH and JNCC have developed a list of Priority Marine Features ( PMFs), to provide a new focus for marine conservation activities across the three pillar approach set out in the Marine Nature Conservation Strategy. Some of these PMFs are UK Biodiversity Action Plan species and habitats. UK BAP priority species are those that are identified as being threatened and requiring conservation. There are 74 UK BAP priority marine species listed as priorities in Scotland. These include sea-fan anemone, fan mussel, native oyster and fireworks anemone. These species can be vulnerable to fishing activities. For example, the fireworks anemone is highly sensitive to mechanical damage from mobile fishing gear, particularly trawling for Nephrops and, to a lesser degree, damage from creels.

5.1.16 SNH and JNCC have made recommendations to Scottish Ministers on PMFs, which comprises a list of PMFs for inshore and offshore waters [19] . This includes such marine species as cod, herring, mackerel and ling. The Marine Atlas identifies key PMFs and the pressures affecting them [20] .

Trends and Pressures

5.1.17 The Marine Atlas reviewed the condition of the five major habitat types described in paragraphs 5.1.2-10. There were few or no concerns about subtidal rock. Intertidal rock and sediments show evidence of deterioration, with one concern being the introduction of such non-native invasive species as wire weed. The most significant level of concern was regarding the condition of shallow and shelf subtidal sediments, mainly as a result of fishing practices such as demersal fishing (trawling) and scallop dredging. There were also some concerns about the effects of trawling on deep sea habitat.

Figure 11. Marine SPAs, SACs and possible MPAs within Scottish Waters

Figure 11. Marine SPAs, SACs and possible MPAs within Scottish Waters

5.1.18 An assessment of the condition of the following species was also made: plankton, cetaceans, grey seals, harbour seals, seabirds, demersal fish, sharks/rays and water birds. Of these, the most concern was expressed about sharks/rays and harbour seals. Populations of sharks/rays are declining and, as these animals are slow growing, late to reach maturity, and typically have low fecundity, populations take some time to recover from such pressures as overfishing. Harbour seal numbers have declined (by over 50%) since 2001 in Shetland, Orkney and the east coast of Scotland, although numbers have remained relatively stable on the west coast and the Inner Hebrides.

5.1.19 Seabird populations are increasing in some areas (Solway Firth and the Clyde, for example) and decreasing in others. In East and West Shetland and along the North Scotland coast, this decrease is most probably related to a shortage of prey species resulting from changes in oceanographic conditions. Like seabirds, waterbirds (wildfowl and waders) are also both increasing and decreasing, depending on the species. The reasons for declines remain to be fully explained but may be due to redistribution of wintering birds across north-west Europe due to climate change effects.

5.1.20 Entanglement of baleen whales in static fishing gear has been observed in Scottish waters, for example, minke whales entangled in creel lines and other ropes. At the time of reporting (2010), such incidents were not considered to be a conservation threat in Scotland [21] .

5.1.21 The Marine Atlas also noted that populations of many commercial fish species are declining, and that this is of particular concern in the Solway Firth, North Channel, Clyde, Minches and Malin Sea, North Scotland coast and West Shetland. Several commercial fish stocks were being fished above the levels consistent with achieving maximum sustainable yield in 2011, including northeast Atlantic mackerel, herring (west of Scotland), cod (North Sea and west of Scotland stocks), blue whiting, saithe and monkfish. Other stocks are fished at sustainable levels, including herring (North Sea), haddock (North Sea, west of Scotland, and Rockall) and Nephrops.

5.1.22 Table 7 sets out the pressures on Priority Marine Features associated with commercial fishing activities. Box 1 sets out current and future pressures on marine biodiversity, flora and fauna.

Table 7. Key Priority Marine Features and Pressures (source: Marine Atlas)

PMF Pressure
Seagrass Suction dredging and bait digging
Blue mussel beds Demersal fishing and bait digging
Native Oyster Over fishing
Northern sea fan and sponge communities Bottom fishing gear
European spiny lobster Vulnerable to overfishing
Horse mussel beds Damage from mobile fishing gear
Flame shell beds Sensitive to damage from mobile fishing gear/dredging.
Serpulid aggregations Vulnerable to demersal fishing
Burrowing sea anemone Main pressures are from dredging and demersal fishing
Northern Feather Star Main pressures are from dredging and demersal fishing
Fan mussel Particularly sensitive to damage from scallop dredging and other fishing gear.
Heart cockle Threatened by dredging and demersal fishing activities
Ocean quahog Risk from mechanical damage particularly caused by bottom fishing gear.
Burrowed mud Vulnerable to trawling for nephrops, bottom trawling and creeling.
Maerl beds Extremely sensitive to physical disturbance/ smothering as a result of scallop dredging and bottom trawling.
Maerl of coarse shell gravel with borrowing sea cucumbers Especially sensitive to physical disturbance from scallop dredging.
Inshore deep mud with burrowing heart urchins Particularly vulnerable to damage from benthic trawling for nephrops.
Shallow tide-swept coarse sands with burrowing bivalves Likely to be targeted for scallop dredging and surf clam fisheries. Sensitive to over fishing and physical disturbance.

Box 1. Pressures on marine biodiversity, fauna and flora

Commercial fishing:
  • removal of target fish species may affect the sustainability of fish stocks, particularly where catches are above the level consistent with achieving maximum sustainable yield
  • discards of fish are a waste of the resource, and also encourage scavenger species
  • bycatch inadvertently catches both non-target fish and other species, generally leading to the death of individuals and subsequent decline in populations
  • the seabed and its benthic habitat may be damaged by mobile fishing gear, with the consequent loss of marine plants and animals
  • removal of target species may also decrease the availability of prey species, leading to declines in populations e.g. of birds
Non-native invasive species may outcompete native species, thereby displacing them from the marine environment. Marine litter can result in the injury and/or death of marine animals, through entanglement, ingestion of litter (including plastic microparticles in particular) or both Dredging:
  • can result in loss of and/or damage to the seabed and the habitats that it supports
  • may give rise to suspended sediments, resulting in decreased water quality and/or smothering of the seabed if these sediments settle out in a different area
  • may disturb marine animals, including through increased noise levels
Marine transport:
  • risks collision of vessels with marine animals, resulting in their injury and/or death, with subsequent population declines
  • may result in increased coastal erosion, through the action of vessel wakes
  • may give rise to elevated nutrient levels in and on the seabed, from fish faeces and excess animal feed, which can result in changes to community composition and/or smothering of the seabed
  • can damage the seabed and its habitat, through anchoring of infrastructure
  • may affect wild salmon, through transmission of sea lice
Marine wildlife watching may result in increased disturbance to populations of marine animals such as whales and dolphins. Recreation:
  • may result in loss of and/or damage to the seabed and its habitat, through anchoring
  • may give rise to increased levels of marine litter
  • may disturb marine animals, through human and/or vessel presence
Offshore renewables, in future:
  • may result in loss of and/or damage to the seabed and its habitat, through anchoring of infrastructure
  • give rise to collision risk, e.g. with birds, mammals, etc
  • result in changes to sediment transport, through changes in energy levels in the water
Climate change, through increasing sea temperatures, acidification, changes to rainfall patterns, etc:
  • may result in populations of marine animals and plants moving further north
  • may give rise to population decline
  • may result in new competitors arriving in Scottish waters, including non-native invasive species

5.2 Ecological/Environmental Status of Water Bodies

5.2.1 Scottish waters are quite different between the east and west coasts. The east coast presents mostly uniform depths and shallow inclines interspersed with localised trenches, while the seabed off Scotland's west coast shelves steeply away from the coast, and deep waters occur relatively close to the land.

5.2.2 There are various mechanisms in place for monitoring and managing the quality of Scottish waters. Each takes a different focus and approach:

  • The Water Framework Directive establishes a framework for the protection of inland surface waters (rivers and lakes), transitional waters (estuaries), coastal waters and groundwater, with the aim of ensuring that all aquatic ecosystems meet 'good status' by 2015. ,[22, 23]
  • River Basin Management Plans [24] have been prepared for the Scotland and Solway-Tweed River Basin Districts to address the requirements of the Water Framework Directive in relation to the management of Scotland's river systems. Both plans also provide an overview of the state of the water environment for their districts.
  • Scotland's coastal waters are monitored by SEPA to measure performance and compliance with targets for coastal water quality status under the Water Framework Directive.

5.2.3 Scotland's seas are mostly classed as being of good or better ecological status under the Water Framework Directive (out to 3 nautical miles). There are some poorer quality waters in certain areas, such as the Firth of Forth and the Firth of Clyde. The key risks to the quality of the water environment are from contamination as a result of marine activities, such as the use of anti-fouling paint, pollution from oil and/or chemical spills, and pollution of coastal waters from activities on land, in particular from agricultural activities.

5.2.4 In 2011, the ecological status [25] of 61% of Scotland's surface water bodies was good or better ( Figure 12) [26] . The following were in good or better condition:

  • 96% of coastal waters;
  • 86% of estuaries;
  • 54% of rivers; and
  • 63% of lochs.

Figure 12. Coastal and Transitional Waters Classification 2011 (Source: Scotland's Environment website) [27]

Coastal and Transitional Waters Classification 2011

5.3 Climatic Factors

5.3.1 In the marine context, climate change has been predicted to lead to an increase in water temperatures, rise in sea levels, changes in wave heights and changes to coastlines. Since 1961, average temperatures in all parts of Scotland have risen for every season [28] and over the last three decades, sea-surface temperatures around the UK coast have also risen by approximately 0.7ºC. [29] At the same time, the seas are becoming more acidic, particularly those to the north and west of Scotland, as increasing amounts of atmospheric carbon dioxide are absorbed at the sea surface. This change in acidity is already causing concern for marine ecosystems. [30]

5.3.2 Sea levels around the UK rose by about 1 mm/yr in the 20th century (corrected for land movement), although it is estimated that recent increases have been higher than this. [31] Under projections from the UKCIP09 model [32] , further rises of between 12 and 76 cm are projected by 2095 [33] , with the added potential for further adverse impacts on coastal areas and transitional waters. It should be noted that lower probability scenarios suggest this rise could be even greater.

5.3.3 Changes to sea levels, increased wave height and storm surges could have serious repercussions for the marine and coastal environments, and the many industries operating in them. As noted previously, climate change is already affecting the marine environment, and increasing the vulnerability of some habitats and species to future pressures.

5.3.4. For example, changes in the climate could result in a shift in distribution and changes in the abundance of fisheries through a loss of certain habitats and species, changes in species, changes in species migration and impact on breeding cycles and food supplies. Climate change may also favour some species leading to, for example, increased diversity of seabed marine life due to the warming of the air and seawater temperatures. [34] Risks from pests, diseases and invasive species may increase. There may also be a decline in ocean primary production and effects on increased ocean acidity. [35]

Vessel emissions

5.3.5 Carbon dioxide ( CO 2) is the primary greenhouse gas emitted through human activities. The main human activity that emits CO 2 is the combustion of fossil fuels (coal, natural gas and oil). Marine diesel (also known as gas oil or red diesel) is used by the majority of fishing vessels and is also the main fuel used by ferries.

5.3.6 In 2011, greenhouse gas [36] emissions from transport in Scotland amounted to 13 MtCO2e, approximately one-quarter of total Scottish emissions. The majority (9.3 MtCO 2e) were from road transport. [37] Emissions from Scottish ferries have been estimated as between 0.22 [38] -0.23 [39] Mt CO 2e.

5.3.7 Overall, transport emissions (including international aviation and shipping) have increased 0.1% since 1990. In 2011, emissions from domestic transport were 0.2% lower than 1990, at 10.47 MtCO 2e, while emissions from international aviation and shipping in 2011 were 2.49 MtCO 2e, up slightly from 2.45 MtCO 2e in 1990 (aviation emissions rose significantly while shipping emissions fell).

5.3.8 Greenhouse gas emissions from vessel engines show a correlation with vessel speed. Greenhouse gas emissions from the fishing fleet, for example, are influenced by a number of factors including the abundance of fish (stocks), the steaming distance to fishing grounds and the technology used, including vessel and engine size, gear type etc. [40] For example, recent figures show that Nephrops trawlers of an average length of 15m and under 250 kW (engine size) operating in the west of Scotland consumed, on average, 390 litres of fuel per day at sea. [41] In contrast, vessels under 10m consumed 134 litres per day at sea. [42]

5.4 Geodiversity

5.4.1 In the coastal zone, the coastline varies between deep and narrow sheltered sea lochs on the west coast, shallow bays and estuaries, and long stretches of exposed coastline. Major Scottish estuaries are the Solway Firth, the Clyde Sea, the Moray Firth, the Firth of Tay and the Firth of Forth. The North Sea coastline is predominantly rocky, with intertidal sediments in the bays and inlets and some extensive stretches of sandy beach. The west coast of Scotland is also typically rocky, with many bays, channels and sea lochs. The coastline of the Western Isles, the north of Scotland and the Northern Isles is also rocky. Along these stretches of coast there are areas characterised by quick transition between rocky shore, sand, gravel and silt. The machair landscapes and coastlines of the western Hebrides, which are created from ancient shell sand deposits, are an ecotype that is largely unique to Scotland.

5.4.2 The offshore environment in Scottish waters ranges from shelf sea areas to deep ocean regions with depths greater than 2,000 m. The continental shelf includes the Malin and Hebrides Shelf Seas, Orkney and Shetland Shelf Seas, and the North Sea. The shelf seas are marked by notable features such as banks ( e.g. Stanton Banks, Viking Bank) and deep channels ( Figure 13).

5.4.3 The western margin of the continental shelf is marked by a sharp change in depth of seabed at about 200 m. The continental slope is a transition area between two systems- the deeper oceanic waters and the shelf sea waters. The deep oceans have a complex bathymetry that is broken up by steep ridges ( e.g. Wyville Thomson Ridge), seamounts ( e.g. Anton Dohrn) and banks ( e.g. Rockall Bank).

5.4.4 Details of the geological nature of the seabed, and the habitats this provides, are set out in paragraphs 5.1.2-10 and Figure 9.

5.4.5 Brooks et al (2012) describe marine geodiversity interests [43] in Scottish waters as being representative of the geological processes that have influenced the evolution and present day morphology of the Scottish seabed. Some of these have been formed by processes unique to the marine environment. Brooks et al (2012) identify the following categories of geodiversity interests:

  • Quaternary of Scotland;
  • Submarine Mass Movement;
  • Marine Geomorphology of the Scottish Deep Ocean Seabed;
  • Seabed Fluid and Gas Seep;
  • Cenozoic Structures of the Atlantic Margin;
  • Marine Geomorphology of the Scottish Shelf Seabed;
  • Coastal Geomorphology of Scotland; and
  • Biogenic Structures of the Scottish Seabed

5.4.6 Protection of Scotland's geodiversity interests, in the main, is currently focused on terrestrial geodiversity. Current protection comprises [44] :

  • Geoparks, a UNESCO designation. There are currently two UNESCO Geoparks in Scotland: North West Highlands Geopark, and Shetland Geopark.
  • National Parks. Geodiversity is one of the special qualities of Scotland's National Parks, and both National Parks contain internationally important geodiversity.
  • National Nature Reserves. Many contain significant geological and geomorphological interest.
  • Sites of Special Scientific Interest. These are the primary statutory mechanism for geodiversity protection in Scotland.
  • Local Nature Conservation Sites. These include Local Geodiversity Sites, sometimes also called Regionally Important Geological and Geomorphological Sites.

5.4.7 SNH/ JNCC have identified geodiversity features for inclusion in the possible nature conservation Marine Protected Areas ( Table 2). These are the pMPAs which have been published for public consultation.

Figure 13. Coastal and offshore waters and features

Figure 13 Coastal and offshore waters and features