Shallow and shelf subtidal sediments

Status: Stable with many concerns 

(Baxter et al, 2011)

Status of benthic habitats; Stable situation since 2012

(United Kingdom Marine Monitoring & Assessment Strategy, n.d)

Inshore subtidal sediments include shingle, gravel,
sand and mud extending to the depth at which there is no effect from waves, typically 50-70m. Shelf sediments extend to ~200m depth. Habitats also include biogenic habitats, for example seagrass beds, and biogenic reefs such as maerl, a red seaweed with a hard chalky skeleton that forms small twig-like nodules accumulating to form loosely interlocking beds creating the ideal habitat for a diverse community of organisms.

The largest component of the Solway seabed is sediment, and therefore the ‘shallow and shelf subtidal sediments’ are the predominant seafloor habitat in the Solway, with shallow sediments being the most common component of these two areas of sediment. Sediment size and texture (fine muds to coarse gravels) depends on the harshness of the tidal environment. The seabed off the coast of Cumbria is almost entirely sedimentary in nature, with a few areas of boulder scars. Deeper muddy sands are found to the south west of St Bees Head.

In the Solway shallow subtidal sediments are extensively sandy. Shallow and shelf subtidal sediments and habitats can be vulnerable to activities which agitate the seabed, such as dredging, bottom trawling, and construction.


Image; Blitterlees at low tide. © Solway Firth Partnership

Shallow and shelf subtidal sediments

Inner Solway

Associated infauna (animals living within the sediment) of sand sediments includes bivalve molluscs,
polychaetewormsbrittlestars and urchins, however the dynamic nature of sand in the inner Solway makes it a challenging environment in which to live. Living on the surface are brown shrimpstarfishspider, hermit crabs and flatfish.

Particularly rich examples of sediment communities are in Luce Bay. Shallow subtidal sediments of the inner Solway are important as nurseries for Irish Sea fisheries.

The main subtidal habitats comprise dynamic sandflats and sediment banks separated by the six main river channels, which are constantly changing their patterns of erosion and accretion. The channels have very little water during low tide, and in fast flood tides currents can reach up to 6 knots.

Benthic communities usually have few species because of these dynamics, mainly a few amphipods and polychaete worms. Species richness increases towards the outer estuary with less extreme environmental conditions, more varied sediment types and increased depth. Richness increases towards the Irish Sea, in silty areas between Castlehill Point and Wigtown Bay, in Allonby Bay on the Cumbrian coast, and in the area between Workington and Abbey Head. In these areas the bivalves: Tellina fabulaNucula sulcata and Abra alba reach maximum abundance. Cutts and Hemingway’s broad scale mapping in 1996 found fine and medium sands in the subtidal zone of the Solway ‘have low species diversity dominated by Nephtys cirrosa, Magelona mirabilis and Bathyporeia pelagica at abundances of approximately 20–25 individuals/0.1m2. The coarser sediment was found to have even lower abundance and species diversity. These sediments are dominated by Nephtys cirrosa with Gastrosaccus spinifer being present in low numbers.‘ (Axelsson et al, 2006)


Image; Common Whelk. © N. Coombey/ Solway Firth Partnership

Shallow and shelf subtidal sediments

Outer Solway

The majority of the outer Solway is shallow subtidal sandy sediments. The fine sands on the edge of channels are characterised by bivalves (Mactra corallina and Donax vittatus) whilst coarser sands contain Spisula solida. Areas of silt and mud are colonised by the polychaete worm, Nephtys cirrosa and the bivalves, Fabula tenuisAbra alba and Nucula sulcata. Also found in these muddier areas are the sea mouse (Aphrodite aculeata) and the starfish, Astropecten irregularis. Beds of eelgrass (Zostera marina) are present at a few locations in shallow subtidal areas on the north coast, usually extending onto the lower shore. Ocean quahog (Arctica islandica) is a species of edible clam which is known to occur in the Solway, favouring sandy or muddy seabeds in which they can bury themselves. Considering this habitat and the preference of depths between 10m and ~280m, it is unsurprising that it is known to occur in the Solway, where the habitat and depth are both favourable. Arctica islandica is also a OSPAR threatened and declining species.

Luce Bay has fine sand mixed with small amounts of mudshell gravel and empty shells and has a rich infauna. This includes the brittlestars, Ophiura ophiura and Amphiura brachiata, the burrowing heart urchin (Echinocardium cordatum) and the wormlike Labidoplax digitate. According to the DGLBAP during the day common cuttlefish (Sepia officinalis) lie buried in the sand. They emerge at night to search for prey, and spawn gregariously on shallow sandy bottoms (Dumfries and Galloway Biodiversity Partnership, 2009). There is a great deal of information on the species and sediments in the subtidal zone in Luce Bay, including benthic grabs samples to classify the sediment type, provided in the NatureScot survey of marine features within the Luce Bay and Sands Special Area of Conservation report (Allen et al, 2014).

Coarser sediments are characterised by species of tube-dwelling polychaete worms such as Pectinaria koreni and Lanice conchilegamasked crabs (Corystes cassivelaunus)brown shrimps (Crangon crangon), molluscs (Natica catena and Cyprina arctica) and the starfish, Astropecten irregularis. Large numbers of the starfish Asterias rubens can rapidly colonise beds of mussels, upon which it feeds.

Commercially exploited species include brown shrimp (Crangon crangon), queen scallop (Aequipecten opercualris) and king scallop (Pecten maximus). The brown shrimp Crangon vulgaris is of particular importance. For flat fish, such as plaice (Pleuronectes platessa) and flounder (Platichthys flesus) polychaete worms are a more important food. Native oysters (Ostrea edulis) are also commercially exploited in Loch Ryan, by the Loch Ryan Oyster Fishery Company, and is one of the UK’s largest native oyster beds (see Aquaculture).

All three species of seagrass, (Zostera spp.) are present in the Solway Firth, on the extreme lower shore and shallow subtidal areas. Beds can be found in several areas including: Loch RyanManxman’s Lake (Kirkcudbright), Auchencairn Bay, Fleet Bay, Baldoon Sands and the Nith Estuary. According to the DGLBAP the ‘nationally rare red seaweed Spyridia filamentosa that reaches its northern limit and is present in Loch Ryan. It is found throughout the loch, particularly in the southern basin. Another red seaweed Chondria dasyphylla, rare in Scotland, grows on gravel banks, pebbles and shells in Loch Ryan. The common red seaweed Rhodothamniella floridula binds coarse sand into sand banks’ (Dumfries and Galloway Biodiversity Partnership, 2009).

Of course, the marine species which thrive in the Solway’s shallow and shelf subtidal zone support the vast range of bird species which can be found in and around the Firth (see Birds for more information on Solway bird species).
Species which thrive in the areas above shallow and shelf subtidal sediments are important for the functioning of the ecosystem, with fish such as lesser sand eels (Ammodytes tobianus) providing food for birds and fish, as well as there being commercially valuable demersal and pelagic fish. As clearly illustrated by the Sea Fisheries section of the Productive chapter of the Solway Review, fisheries in the Solway rely on shellfish for the vast majority of landings on both sides of the Firth, however there is some landing value, particularly for plaice (Pleuronectes platessa) and demersal landings on the English side. The DGLBAP also suggests common sole (Solea solea), flounder (Pleuronectes flesus), and small numbers of haddock (Melanogrammus aeglefinus) can also be found on soft, muddy ground, surface mud or sandbanks, and coarser sand banks, respectively.

Elasmobranchs are also common on the shallow or shelf subtidal sediments of the Solway, with small spotted catsharks (Scyliorhinus caniculus) and tope (Galeorhinus galeus) favouring sandy/muddy sediments, and summertime sand/gravel bottoms respectively (see Sharks, Skates and Rays for more information on Solway elasmobranchs). A lesser known species known to also frequent the Solway in the late summer is the leatherback turtle (Dermochelys coriacea). There was a recent sighting of a leatherback turtle in the Solway, the video footage has been posted on Youtube and can be seen here.


Image; Scotland’s National Marine Plan Interactive, with layers (links will provide usage licence, data provider, etc); ‘Solway Region (mask)‘ © Crown Copyright, All rights reserved, and ‘Ocean quahog (Arctica islandica) (Priority Marine Feature) (SNH WMS)‘ © Crown Copyright, All rights reserved, ‘Native Oysters – Ostrea edulis beds on shallow sublittoral muddy mixed sediment (Priority Marine Feature) (SNH WMS)‘ © Crown Copyright, All rights reserved

Shallow and shelf subtidal sediments

Biogenic reefs

Biogenic reefs are also discussed in the Subtidal Rock, and Intertidal rock, sediments and biodiversity sections of the Solway Review. They are habitats which are formed from hard matter by a living organism, creating a new habitat in which other organisms, in addition to those which form the reef, can live. Seagrass is also a biogenic habitat (not a reef as seagrass does not create solid matter) as it creates a habitat.

In the Solway there are several species which form biogenic reefs, such as blue mussels (Mytilus edulis) and native oysters (Ostrea edulis) which are known to grow in the subtidal areas of the Solway. Subtidal biogenic reefs in the Solway tend to be predominantly blue mussels with native oysters in Loch Ryan. Maerl beds also occur in Luce Bay but are significantly more common further north on the west coast of Scotland, and are more common in Scotland than England.

The edible blue mussel (Mytilus edulis) beds are common along the Scottish and English Solway coasts, predominantly in the intertidal zone (see Intertidal rock, sediments and biodiversity). Dubmill North bed is below mean low water springs on the English side of the Firth as are many beds on the Scottish side. The inner Solway also has blue mussel beds according to both NatureScot, and EMODnet Seabed Habitats data (displayed in The Marine Life Information Network website). The Silloth channel is known to have very high densities of blue mussels, with Axelsson et al (2006) recording 10,500 individuals per 0.1 m². According to a 1997 report from Scottish Natural Heritage (now NatureScot), the Solway was the location in Scotland most reported to feature ‘transient populations’ of mussels. Due to the mobile nature of sediments in the Solway there is the potential for blue mussel beds to establish in an area and then be displaced. Elsewhere beds tend to become established with location remaining consistent over long periods (McKay & Fowler, 1997). The North Western Inshore Fisheries and Conservation Authority (NWIFCA) currently has a mussel bed open, with restrictions, in the Solway Firth (see NWIFCA open mussel beds and restrictions here).

Forming at depths between 5-70m, small horse mussel beds (Modiolous modiolus) are found along the Wigtownshire coast, as well as in Loch Ryan and Burrow Head (Dumfries and Galloway Biodiversity Partnership, 2009). Depending on factors such as depth and water movement, in areas where dense horse mussel beds occur it is likely there are hundreds of species, including sponges, soft corals, anemones, hydroids, tubeworms, brittlestars, urchins, starfish, barnacles, and crabs (Dumfries and Galloway Biodiversity Partnership, 2009). Allen et al (2014) found significant numbers of dead horse mussel shells in Luce Bay, however clarified that these are ‘unlikely to be found at the source of the original mussel beds, and their observed positions are more likely due to current / tide or anthropogenic effects.’ Presence of horse mussel beds in the Solway is discussed in the Subtidal rock section of the Solway Review.

The Ross/reef worm (Sabellaria spinulosa) also form biogenic reefs in the subtidal zone of the Solway, and honeycomb worm (Sabellaria alveolata) reef is relatively common in the intertidal zone of the Solway (see Intertidal rock, sediments and biodiversity) but can also occur in the subtidal zone. In 2006, however, it was reported that a high abundance of Sabellaria alveolata (and blue mussels as discussed above) was discovered in the Silloth Channel (Axelsson et al, 2006), a subtidal area beyond Beckfoot flats into the Solway.

Finally, maerl beds, formed of calcareous red algae, are found in Luce Bay. Mearl bed habitat is also an OSPAR threatened and declining habitat (as are native oyster beds, Modilous modiolus and Sabellaria spinulosa reefs), and are an important blue carbon store. However, they are potentially under threat of damage from climate change and suffer from slow growth, meaning if maerl beds are damaged, for example by activities such as dredging, regrowth would be a slow process. Luce Bay and Sands Special Area of Conservation (SAC) includes ‘reefs’ as a qualifying interest for designation. A 2014 survey carried out in Luce Bay to explore the features in the site provided clear evidence of extensive maerl beds in the site; “A large maerl bed composed of Phymatolithon calcareum was found in the middle of the mouth of the bay. Live maerl cover ranged from 5 –  30%, and coverage with dead maerl fragments reached up to 90 –  95%. This represents the first confirmed record of a maerl bed within Luce Bay, and was the only Priority Marine Feature observed during the survey.’ (Allen et al, 2014)

There may even be spatial competition in the Solway between different types of biogenic reefs. According to Axelsson et al (2006); ‘subtidal blue mussel beds on sediment are believed to compete for space with reefs of the honeycomb worm Sabellaria alveolata in the outer part of the Solway Firth’.


Image; Honeycomb worm reef © G. Reid/ Solway Firth Partnership

Shallow and shelf subtidal sediments

Burrowed Mud

This is soft muddy habitat which is home to, and burrowed by, species including the commercially important Norway lobster (Nephrops norvegicus).

Scotland is where the vast majority of UK records for both inshore and deep burrowed mud are located. Around 95% of these records are from the northern North Sea, sea lochs of western Scotland and the Hebrides.

There are a number of important burrowed mud communities and species as listed in Baxter et al (2011); sea pens and burrowing megafauna in circalittoral fine mud, burrowing megafauna and Maxmuelleria lankesteri in circalittoral mud, tall sea pen (Funiculina quadrangularis), fireworks anemone (Pachycerianthus multiplicatus) and the mud-burrowing amphipod (Maera loveni), other burrowed mud habitats. From the data for these six burrowed mud features in the National Marine Plan Interactive (NMPI), only one (seapens and burrowing megafauna in circalittoral fine mud) is found in the Solway, off the coast of the Rhins north-west of North Cairn, on the boundary between the Solway and Clyde marine regions. According to the Scottish Government’s 2019 regional locational guidance for offshore wind energy; ‘There are a number of records of benthic PMFs throughout the South West region, including kelp and seaweed species, fan mussel (Atrina fragilis), maerl (Phymatolithon calcareum), seagrass species, burrowed mud, tall sea pens (Funiculina quadrangularis), native oyster (Ostrea edulis) and blue mussel (Mytilus edulis).’ Despite the seemingly positive confirmation of other burrowed mud habitats in the Solway, the South West region for offshore energy includes a large portion of the Clyde Marine Region, where both fan mussels and tall sea pens have been recorded, and can be seen in the NMPI data layers (see data layers for fan mussels and tall sea pens). Furthermore, on exploring data within the National Biodiversity Network (NBN) Atlas, mud dwelling species listed above (Maxmuelleria lankesteri, Funiculina quadrangularis, Pachycerianthus multiplicatus, Maera loveni) have not been recorded in the Solway. Note, the NBN Atlas has no records of the fan mussel in the Solway.

Species living on the surface of these sediments include the brown shrimp (Crangon vulgaris) and the flounder (Platichthys flesus)In the summer when salinity increases, less tolerant species such as the hermit crab (Pagurus bernhardus) and the cuttlefish (Heterosepiola atlantica) travel up the estuary. Fish feed over the intertidal flats at high tide. Fishing occurs in the channels when the tide is out. Diversity increases moving seawards with more species appearing such as spider crabs (Macropodia rostrata and Hyas araneus), swimming crabs (Portunus depurator and Portunus holsatus), starfish (Solaster papposus) and brittlestars (Ophiura texturata). Mobile epifauna form the main food source for fish species and the brown shrimp is of particular importance. Polychaete worms are important food for flatfish such as plaice (Pleuronectes platessa) and flounder (Platichthys flesus).


Shallow and shelf subtidal sediments


The shallow subtidal sediments of the inner Solway are some of the best estuarine examples of muddy sandbanks affected by reduced salinity (see Protected areas). They are important for fisheries in the Solway and as nursery areas for the Irish Sea as a whole. The north coast seagrass (Zostera spp.) are of particular nature conservation importance. Rich examples of sediment communities have been recorded at Luce Bay. The estuaries support high population of overwintering birds, particularly, the red-throated diver (Gavia stellate), great crested grebe (Podiceps cristatus), Slavonian grebe (Podiceps auratus), cormorant (Phalacrocorax carbo), eider (Somateria mollisima), common scoter (Melanitta nigra), scaup (Aythya marila) and the red-breasted merganser (Mergus serrator). The extensive examples of rocky scars on the Cumbria coast support marine communities of nature conservation and commercial fisheries interest. Subtidal; biogenic reefs, mixed sediments, sand, and coarse sediments are all included in the designated features of the Allonby Bay Marine Conservation Zone

Shallow and shelf subtidal sediments are considered subtidal habitats, and therefore are an indicator of assessing the health of ‘benthic habitats’ for the purpose of measuring descriptors 1 (Biological Diversity) and 6 (Seafloor Integrity) for progress towards Good Environmental Status (GEnvS). For the purposes of assessing GEnvS for benthic habitats, indicators cover ‘rock and biogenic habitats, predominant sediment habitats, and intertidal habitats against targets’ (Department for Environment, Food, and Rural Affairs, 2019). Achieving GEnvS in the marine environment is required as per the Marine Strategy Framework Directive to provide more effective marine environment protection and sustainable use. For biogenic habitats in the Celtic Seas, GEnvS has not yet been achieved with the extent of physical loss for these habitats being inconsistent with GEnvS. Additionally, the achievement of GEnvS for predominant sediment habitats is ‘uncertain’.

The value of shallow and shelf subtidal habitats is reflected in the lists of national importance which they appear on, such as Scottish Biodiversity List, Habitats of Principal Importance, UK Biodiversity Action Plan priority habitats, and many more. Scroll down to ‘Pressures on Features’ to see a list of habitats and national lists in which they feature. Certain habitats are also of international importance appearing on, for example, OSPAR’s list of threatened and/or declining species & habitats list.


Image; Cormorants. © N. Coombey/ Solway Firth Partnership

Shallow and shelf subtidal sediments


Status: Stable with some concerns 

(Baxter et al, 2011)

Status of pelagic habitats; Stable situation since 2012

Status of food webs: Improving since 2012

(United Kingdom Marine Monitoring & Assessment Strategy, n.d)

The word plankton is taken from Greek, meaning to wander. It is used to refer to the marine plants and animals which are carried about by the movements of the water rather than by
their own ability to swim. Phytoplankton are microscopic plants whereas Zooplankton are small animals and juvenile stages of larger animals. Although the majority of the plankton are small, mainly microscopic, some plankton can be large such as the lion’s man jellyfish, (Cyanea capillata) which can reach 2.5m in diameter with even longer tentacles. The phytoplankton are an important part of the food chain, converting the sun’s energy into food for herbivorous zooplankton to ‘graze’ on and in turn to be fed upon by carnivorous zooplankton, fish and other marine organisms. Many species of subtidal and intertidal communities, including commercially important fish and shellfish, have planktonic stages in their life cycles.

In the eastern Irish Sea, diatoms, dinoflagellates and
zooplankton dominate phytoplankton. According to the International Council for the Exploration of the Sea; ‘Though there were no significant trends in phytoplankton abundance in the Irish Sea between 1996 and 2010, longer-term trends indicate a decline in both diatom and dinoflagellate abundance (International Council for the Exploration of the Sea, 2019). Crustaceans called copepods dominate zooplankton.
Depthtidal mixing and temperature
stratification strongly influence plankton abundance in coastal waters. Availability of food and nutrientslarval survival, fish recruitment and timing of egg production is closely linked to the dynamics of the plankton populations. Environmental perturbations which affect plankton may affect other organisms higher in the food chain e.g. fishbirdsmarine mammals.

The plankton component is a vital part of the marine food chain and is closely interlinked with seabed and water column ecosystems. Phytoplankton blooms are a normal feature in the seasonal development of plankton. However, some blooms may reach exceptional proportions (with more than one million organisms per litre), or contain species (principally dinoflagellates) capable of causing noxious effects. Such blooms may have an important economic impact on mariculturefisheries and tourism, as well as being toxic to humans.

The colonial dinoflagellate, Phaeocystis pouchetii forms spring blooms in Liverpool Bay and further north along the coast of Lancashire and Cumbria potentially as far up the Cumbrian coast as St Bees Head. Phaeocystis pouchetii has been previously noted in 1898 as common around the Faroes and west of Scotland (Gowan et al, 2009 noting Cleve, 1900). It is not clear whether the species occurs with any significance in the Solway Firth. On dying the species can cover intertidal sediments with a mucilaginous blanket and can kill benthic animals. According to the original Solway Review and Vincent et al (2004), the dinoflagellate, Gyrodinium aureolum produces ‘red tides’ and occurs in the Solway Firth. A red tide forms when the dinoflagellate is present in such large numbers that the water becomes discoloured. The red tides have been associated with fish and invertebrate mortalities (Helm et al. 1974 referenced in the original Solway Review). The other major bloom-forming species is the luminescent dinoflagellate, Noctiluca scintillans.

Plankton within the Solway Firth play a vital role in the functioning of marine and estuarine ecosystems. Many species of nature conservation or commercial interest spend part of their life cycles as planktonic stages. Many others depend directly or indirectly upon the plankton for food including birdsseals and humans.

Assessment of pelagic habitats contributes towards achieving ‘Good Environmental Status’ (GEnvS) in the UK’s seas for descriptors 1 (biological diversity) and 4 (food webs). Changes in plankton communities and changes in plankton biomass are indicators used to assess ‘pelagic habitats’. 

This three-stage process, with an updated Part 1 of the Marine Strategy was published in 2019. As progress towards GEnvS is monitored and assessed by experts and scientists, the failure to achieve or achieving of GEnvS provides a UK-wide indication for the assessed aspects of the UK’s seas. In terms of ‘pelagic habitats’ the 2019 assessment considered the status of achieving GEnvS to be ‘uncertain’. This is because; ‘Plankton communities in the Greater North Sea and Celtic Seas are experiencing changes in biomass, abundance, and community structure of plankton that may have consequences on the functioning, dynamics and structure of the whole marine ecosystem. Prevailing oceanographic and climatic conditions are likely to be driving these changes, but the extent of pressure from direct human activities is unclear’ (Department for Environment, Food, and Rural Affairs, 2019).

The status of food webs is made using the results of assessing pelagic habitats, in addition to other assessments on fish, birds, seals, and cetaceans. Similarly, for food webs GEnvS achievement is ’uncertain’, and in terms of plankton specifically ‘plankton communities are changing…It is known that components of the marine food web are changing, but it is not clear how they are affecting each other’ (Department for Environment, Food, and Rural Affairs, 2019).


Image; Lady Bay. © N. Coombey/ Solway Firth Partnership

Shallow and shelf subtidal sediments

Recent Trends

Shallow subtidal sediments are relatively degraded. However, seagrass beds appear to have continued to expand since the 1990’s.

Subtidal and shelf habitats and the species that live within them are particularly vulnerable to damage from dredging and bottom trawling.

Oil and gas exploration, drilling pipelines, and other activities which make contact with the seabed can result in localised temporary or permanent loss or damage to subtidal communities. Although activities related to oil and gas are of little threat to the Solway at present, potentially damaging activities would include disturbance from seabed development (including offshore renewable energy), anchoring and pollution.

Extraction of marine aggregates can result in loss or damage to subtidal habitats and affect sediment transport processes.

Discharge of sewage and industrial pollutants can also alter the composition of subtidal communities, although generally the quality of these discharges is being improved. The firing of >6000 depleted uranium projectiles into the Solway by the Ministry of Defence may have had some impact (not proven). Radioactive discharges from Sellafield are another concern (see Hazardous substances).


Image; Wood on the Solway shore. © Solway Firth Partnership. Photographer; Keith Kirk

Shallow and shelf subtidal sediments

Priority habitats and pressures

Priority marine habitats found on/in shallow and shelf subtidal sediments;

Scottish Priority Marine Features (PMF) List available here. NatureScot published Descriptions of Scottish PMFs in 2016, available here.
UK Biodiversity Action Plan (UK BAP)* Habitat descriptions available here. Habitat descriptions for each specific priority habitat are available here. UK Biodiversity Action Plan Priority Marine Species are available here.
Species and Habitats of Principal importance (SPI) England. List available here.
Features of Conservation Interest (FOCI) (Marine Conservation Zone Features) England. List available here.
Scottish Biodiversity List (SBL) Scotland. List available here.


*Note; The UK Biodiversity Action Plan has been succeeded by the UK-Post 2010 Biodiversity Framework and is the document for the joint UK-wide work towards achieving the EU Biodiversity strategy and Aichi Targets. Governments of the UK also each have their own biodiversity strategies focussed on more specific country level biodiversity. UK BAP priority species and habitats are those which are considered to be most in need of conservation and the most threatened on a UK-wide level. The lists are used to help each UK jurisdiction draw up their own specific list.

Category Broad Feature Category (see each list to explore
specific component
biotopes, subcategories
specific to shallow and shelf subtidal habitats only some of which occur in the Solway)
Type Pressures/ Sensitivities Presence
Shellfish Ocean quahog (Artica islandica) PMF/ FOCI Trawling, dredging, climate change, physical changes, abrasion, disturbance Scotland, England
Biogenic reefs Reef/ Ross worm reefs

(Sabellaria spinulosa)

SPI/ FOCI/ UK BAP Dredging, trawling and fishing, pollution, disturbance Scotland, England
Honeycomb worm reefs

(Sabellaria alveolata)

SBL/ SPI/ FOCI/ UK BAP Climate change, prolonged burial, change in sediment dynamics, development, competition for space with common mussels, variable recruitment, natural mobility, exploitation, development, water abstraction, disturbance Scotland, England
Blue mussel beds (Mytilus edulis) PMF/ SBL/ SPI/ FOCI/ UK BAP Commercial fisheries, water quality, coastal developments, anchoring Scotland, England
Horse mussel beds (Modilous modiolus) PMF/ SBL/ SPI/ FOCI/ UK BAP Physical damage to the seabed from mobile fishing gear which may severely damage or even destroy beds, activities which physically interact with the seafloor (such as drilling, development, aggregates), contamination (bioaccumulation) Scotland, England
Native Oyster/ beds (Ostrea edulis) PMF/ SBL/ SPI/ FOCI/ UK BAP Overfishing, pollution, disease, INNS, habitat loss, predators Scotland
Maerl beds PMF/ SBL/ SPI/ FOCI/ UK BAP Commercial extraction, scallop dredging, heavy anchors and mooring chains, finfish farms, eutrophication, obstruction to water flow Scotland, England
Habitats Burrowed mud PMF Fish farms, smothering, nutrient enrichment, chemical pollution, trawling Scotland, England
Kelp beds (Laminaria Hyperborea) PMF Obstruction, pollution, fishing Scotland, England
Kelp and seaweed communities on sublittoral sediment PMF Anchoring, nutrient enrichment, disease, natural cycles, physical disturbance, INNS, marine pollution and increased turbidity Scotland, England
Mud habitats in deep water SBL/ SPI/ FOCI/ UK BAP Demersal fishing, marine fish farms, pollution, development, anchoring, offshore oil rigs and other oil installations Scotland, England
Seagrass beds PMF/ SBL/ SPI/ FOCI/ UK BAP Anchoring, nutrient enrichment, disease, natural cycles, physical disturbance, INNS, marine pollution and increased turbidity Scotland, England
Tide-swept coarse sands with burrowing bivalves PMF Scallop dredging, physical disturbance Scotland, England
Tide-swept algal communities PMF Harvesting (may have effects on habitat structure and species diversity), development, activities which reduce water flow.  

Scotland, England


Tide-swept Channels SBL/ SPI/ FOCI/ UK BAP Obstruction, pollution, fishing Scotland, England
Subtidal sands and gravels SBL/ SPI/ FOCI/ UK BAP Pollutants in riverine discharge, trawling and aggregate dredging activities, aggregate extraction in licensed areas, other physical disturbances, organic pollution from sewage discharge, oil exploration Scotland, England

Several of the Scottish PMF’s include the same component biotopes as other priority lists under different names. For example one of the Solway component biotope of ‘Tide-swept algal communities’ is ‘Laminaria hyperborea on tide-swept infralittoral mixed substrata’. This also an indicative biotope of ‘Tide-swept Channels’ for FOCI, SPI, and UK BAP lists.

Shallow and shelf subtidal sediments


Cumbria Biodiversity Data Centre (n.d.). Available here. (Accessed: 10.03.18)

Cumbria Biodiversity Partnership (2001). The Cumbria Biodiversity Action Plan. Available here. (Accessed: 01.04.21)

Cutts, N. & Hemmingway, K. (1996). The Solway Firth: broad scale habitat mapping. Scottish Natural Heritage (now NatureScot) Research, Survey and Monitoring Report No. 46. Available here. (Accessed: 22.07.20)

Joint Nature Conservation Committee (2012). UK Biodiversity Action Plan (2015). Available here. (Accessed: 07.0.18)

Joint Nature Conservation Committee (2011). UK Biodiversity Action Plan Priority Habitat Descriptions. Available here. (Accessed: 07.03.21)

Joint Nature Conservation Committee (2007). UK Biodiversity Action Plan Priority Marine Species. Available here. (Accessed: 07.03.18)

Marine Life Information Network (n.d.). Habitats listed as Features of Conservation Interest (FOCI). Available here. (Accessed: 14.05.20)

Marine Life Information Network (n.d.). Habitats listed as ‘habitats of principal importance’. Available here. (Accessed: 14.05.20)

Marine Management Organisation. (n.d.). Marine Planning Evidence Base. Available here. (Accessed: 14.05.18)

Marine Scotland (n.d.). Scotland’s National Marine Plan Interactive. Available here. (Accessed: 06.08.19)

Mills, F., Sheridan, S. and Brown S., (2017). Clyde Marine Region Assessment. Clyde Marine Planning Partnership. pp 231, Available here. (Accessed: 14.05.18)

NatureScot (2020). Priority Marine Features in Scotland’s Seas. Available here. (Accessed: 01.04.21)

NatureScot (2020). Scottish Biodiversity List. Available here. (Accessed: 04.05.21)

Solway Firth Partnership (1996). The Solway Firth Review, Solway Firth Partnership, Dumfries. Available here. (Accessed 23.07.19)

Tyler-Walters, H. & Sabatini, M. (2017). Arctica islandica, Icelandic cyprine. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, Plymouth: Marine Biological Association of the United Kingdom. Available here. (Accessed: 28.05.18)

Tyler-Walters, H., James, B., Carruthers, M. (eds.), Wilding, C., Durkin, O., Lacey, C., Philpott, E., Adams, L., Chaniotis, P.D., Wilkes, P.T.V., Seeley, R., Neilly, M., Dargie, J. & Crawford-Avis, O.T. (2016). Descriptions of Scottish Priority Marine Features (PMFs). Scottish Natural Heritage (now NatureScot) Commissioned Report No. 406. Available here. (Accessed: 28.04.21)

UK National Ecosystem Assessment (2011). The UK National Ecosystem Assessment Technical Report. UNEP-WCMC, Cambridge. Available here.  (Accessed: 28.05.18)


In-Text References;

Allen, C., Axelsson, M., Doran, J., & Dewey, S. (2014). Survey of marine features within the Luce Bay and Sands Special Area of Conservation (SAC). Scottish Natural Heritage (now NatureScot) Commissioned Report No. 738. Available here. (Accessed: 22.03.21)

Axelsson, M. , Dewey, S. , Tourell, A. and Karpouzli, E. (2006). Site condition monitoring – the sublittoral sandbanks of the Solway Firth. Scottish Natural Heritage (now NatureScot) Commissioned Report No. 155 (ROAME No. F02AA409). Available here. (Accessed: 21.03.21)

Baxter, J.M., Boyd, I.L., Cox, M., Donald, A.E., Malcolm, S.J., Miles, H., Miller, B., Moffat, C.F., (Editors), (2011). Scotland’s Marine Atlas: Information for the national marine plan. Marine Scotland, Edinburgh. pp 191. Available here. (Accessed: 22.07.19)

Department for Environment, Food, and Rural Affairs (2019). Marine strategy part one: UK updated assessment and Good Environmental Status. Available here. (Accessed: 22. 01.21)

Dumfries and Galloway Biodiversity Partnership (2009). Dumfries and Galloway Local Biodiversity Action Plan. Available here. (Accessed: 01.04.21)

Gowen, R. J., Tett, P., Bresnan, E., Davidson, K., Gordon, A., McKinney, A., Milligan, S., Mills, D., Silke, J. & Crooks, AM. (2009). Anthropogenic nutrient enrichment and blooms of harmful micro-algae. Report prepared for the Department for Environment, Food and Rural Affairs Available here (direct download link). (Accessed: 01.04.21) Noting; Cleve, P. (1900). The Seasonal Distribution of Atlantic Plankton Organisms. D.F. Bonniers (Göteborg), pp368

Helm, M.M., Hepper, B.T., Spencer, B.E. & Walne, P.R. (1974). Lugworm mortalities and a bloom of Gyrodinium aureolum in the eastern Irish Sea, autumn 1971. Journal of the Marine Biological Association of the United Kingdom, 54: 857-869. (Referenced directly in the original Solway Review, unable to find a freely accessible copy of the paper online)

International Council for the Exploration of the Sea (2019). Celtic Seas Ecoregion – Ecosystem overview. In Report of the ICES Advisory Committee, 2019. ICES Advice 2019, Section 7.1. Available here. (Accessed: 12.06.21)

McKay, D.W. and Fowler, S.L. (1997). Review of the Exploitation of the Mussel, Mytilus edulis, in Scotland. Scottish Natural Heritage (now NatureScot) Review. No 68. Available here. (Accessed: 28.07.20)

Scottish Government (2019) Offshore wind energy – draft sectoral marine plan: regional locational guidance. Available here. (Accessed: 28.05.21)

United Kingdom Marine Monitoring & Assessment Strategy (n.d). Eutrophication. Available here. (Accessed: 15.12.20).

Vincent, M.A., Atkins, S.M., Lumb, C.M., Golding, N., Lieberknecht, L.M. and Webster, M. (2004). Marine nature conservation and sustainable development – the Irish Sea Pilot. Report to Defra by the Joint Nature Conservation Committee, Peterborough. Available here (direct download link). (Accessed: 21.05.21)


Image; Limpet. © N. Coombey/ Solway Firth Partnership