Location and physical characteristics
Figure 1: Fladen and Moray Firth Offshore, Offshore Marine Region. The thicker white line delineates the extent of the Fladen and Moray Frith Offshore OMR. For a map of all SMRs and OMRs, see Figure 5 here
| Sea area (km2) | 40,261 |
| Deepest point (m) | 248 |
| Shallowest point (m) | 35 |
| Average depth (m) | 111 |
| Tides (m) | 0.8 – 3.2 |
| Salinity | 34.46 – 35.44 |
| Sea surface temperature (°C) | 7.15 – 14.38 |
The Fladen and Moray Firth Offshore OMR is situated to the North-east of Scotland. Due to the characteristics of the tide in the North Sea, the spring tidal range, the difference between mean high and low water at spring tide, decreases with increasing distance offshore from the North-east coast from more than 3 m to approx. 1 m (see Figure 1, Sea level and tides Assessment). Tidal currents are mainly in a north-south direction (see Circulation Assessment)
The circulation forms an extension of the currents that transport coastal and Atlantic water into the North Sea between Orkney and Shetland and to the east of Shetland. Towards the southern boundary of the Fladen and Moray Firth Offshore OMR, the non-tidal circulation is directed eastward into the North Sea, as the Dooley Current. The circulation pattern shows seasonal variation in both strength and positioning, due to changing wind patterns and water column stratification. In summer, frontal jets occur along the density fronts separating regions of the shelf that remain mixed and those that stratify due to seasonal heat input.
The seabed is predominantly composed of sand and mud habitats with some patches of coarse and mixed sediments. It includes an unusual geological tunnel valley known as the Fladen Deeps, which was likely created by erosion of meltwater under an ice sheet in former ice ages. In places, the tunnel-valley can stretch for 40 km and be up to 4 km wide. There is also a series of crater-like depressions on the sea floor, some containing the Annex I habitat Submarine structures made by leaking gases. Large blocks, pavements slabs and smaller fragments of methane-derived authigenic carbonate (MDAC) have been deposited through the process of precipitation during the anaerobic oxidation of methane (AOM) by a specialised community of microbial organisms. The AOM activity at the sulphate-methane interface beneath the seabed results in the presence of poisonous hydrogen sulphide in the sediments.
Productive
The Fladen and Moray Offshore OMR, as with other OMRs, does not have the activities associated with an SMR such as water abstraction, salmon and seatrout fishing and aquaculture. However, the Scottish Governments Sectoral Marine Plan for offshore wind energy draft plan options (2020) show areas for development within this OMR. To this extent, there is a similarity between this OMR and the Long Forties OMR, situated to the south. There are further similarities between these two OMRs with respect to their historical contribution to the Scottish marine economy. Both have been significant contributors to the offshore oil and gas industry for many years.
Figure 2: Changes that have taken place in the Fladen and Moray Firth Offshore OMR by Sector. Although the period 2014 – 2018 inclusive has been used where possible, there are some entries when a slightly different time period has been used.
In 2018, 25.8 million tonnes of oil, natural gas liquids and gas were produced from the Fladen and Moray Firth Offshore OMR, the highest value of any OMR. Over the years, significant infrastructure associated with the oil and gas industry has developed in the Fladen and Moray Firth OMR including a hydrocarbon pipeline to Orkney. Several other key pipelines pass through this OMR on their way to landfall on the North-East of Scotland (see Oil and Gas Assessment].
Historically, there has been a significant demersal fishery in this OMR, which continues today with current landings from some of the International Council for the Exploration of the Sea (ICES) rectangles within this OMR exceeding 2,000 tonnes in 2018.
The Productive Assessment was undertaken on a sectoral basis, with a focus on 2014 - 2018. For many sectors, there were changes over the period 2014 – 2018 (Figure 2).
Pressures from human activities
As part of SMA 2020, an assessment of the main pressures from human activities in each of the Scottish Marine Regions and Offshore Marine Regions was undertaken through a MASTS-led workshop. The process and outcomes are presented in detail in the Pressure from Activities section. Five main pressures identified for the Fladen and Moray Firth OMR ordered as per the MASTS-led Pressure Assessment Workshop were:
| Priority [1] | Pressure (FeAST classification) [2] | Main healthy and biologically diverse components affected [3] | Main contributing FeAST activity /activities to pressure [4] | Associated productive assessments [5] |
|---|---|---|---|---|
| 1 | Surface abrasion |
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| 2 | Sub-surface abrasion/penetration |
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| 3 | Removal of target species (including lethal) |
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| 4 | Removal of non-target species (including lethal) |
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| 5 | Litter |
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Clean and safe
The assessments cover hazardous substances and marine litter which have the potential to impact on habitats and species as well as being a consequence of human activity. Although sources of litter or contaminants may be local, there are cases when the source is some distance from the impacted area. The main findings for the Fladen and Moray Firth Offshore OMR are:
Hazardous substances:
Hazardous substances (polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and heavy metals (Hg, Cd and Pb)) assessments in sediment and biota (fish and shellfish) were undertaken at the scale of the five Scottish biogeographic regions: Atlantic North-West Approaches, Irish Sea (Clyde and Solway), Minches and Western Scotland, Scottish Continental Shelf and Northern North Sea. Fladen and Moray Firth Offshore OMR is in the Northern North Sea biogeographic region. Contaminant concentrations in the Northern North Sea biogeographic region were generally above background but below concentrations where adverse effects could occur. In addition, concentrations in sediment and biota were stable or declining for all hazardous substances measured. Two sediment and two fish sites are in Fladen and Moray Firth Offshore OMR, these sites were typical of the Northern North Sea, with no major concerns.
A number of biological effects were also measured and assessments undertaken at the scale of the five Scottish biogeographic regions. The contaminant specific biological effects (PAH bile metabolites and 7- ethoxyresorufin O-deethylase (EROD) activity) in the Northern North Sea were consistent with the hazardous substances and showed a limited exposure to contaminants. The Northern North Sea showed an increase in fish disease in some years but this could not be linked to exposure to contaminants. Two fish sites in the Fladen and Moray Firth Offshore OMR were assessed for biological effects, EROD activity was consistent with the Northern North Sea regional assessment. The fish disease index was acceptable at these sites.
Marine litter:
Due to the lack of assessment criteria for marine litter and microplastic, status assessments were not possible. However, litter and microplastics are present in all sampled OMRs, including Fladen and Moray Firth Offshore OMR. Fladen and Moray Firth Offshore OMR has a relatively low concentration of microplastics in its surface water (< 5,000 microplastics per km2 of sea surface).
Seafloor litter was assessed at the scale of the biogeographic regions; Fladen and Moray Firth Offshore OMR is included in the Northern North Sea biogeographic region. The evidence indicates that there is no consistent trend in seafloor litter density between 2012 to 2018 inclusive for the Northern North Sea.
Healthy and biologically diverse
This section summarises the information from the Marine Protected Areas (MPAs) and intertidal and continental shelf habitats assessments from SMA2020. It also provides information from the relevant case studies relating to Priority Marine Features (PMFs), with a focus on habitats. Further work is required to enable assessment at a regional scale for most species; this will be included in Scotland’s next marine assessment.
At a regional scale for MPAs the focus is on the number of new MPAs, MPAs with new spatial management measures, and MPAs in which spatial management measures are in discussion, as well as recognising monitoring that has been undertaken between 2012-2018. For the marine habitats, the focus is on interpreting the relevant intertidal and continental shelf habitat assessments – biogenic habitats, predicted extent of physical disturbance to the seafloor (BH3) and intertidal seagrass beds. For PMFs, a summary is provided of the changes in our understanding of the habitats of most relevance to the Fladen and Moray Firth Offshore OMR, including changes in distribution and extent.
Marine Protected Areas
Progress in developing the Scottish MPA network
There are 3 MPAs in the Fladen and Moray Firth Offshore OMR that contribute to the Scottish MPA network (see Table 1). Some of these MPAs overlap completely or partially in terms of their spatial coverage and/or the features (habitats, species, etc.) they were set up to help conserve. They are counted as separate MPAs because they have been established under different legislation which influences the way in which they are managed. Also note that there are MPAs that straddle the boundaries between different OMRs or in some cases overlap each other. Where this is the case, these MPAs have been counted as contributing to the MPA network in all of the SMRs / OMRs in which they are present. This means that the total number of MPAs in Scotland cannot be calculated through combining the SMR / OMR totals. Please see the Marine Protected Area assessment which contains statistics for the Scottish MPA network as a whole.
Table 1. Numbers of types of MPAs in the Fladen and Moray Firth Offshore OMR that contribute to the Scottish MPA network, including the number of new MPAs introduced since 2012.
|
Type of MPA |
Abbr. |
Total no. of MPAs |
No. of new MPAs 2012-2018 |
|
Special Area of Conservation |
SAC |
1 |
0 |
|
Nature Conservation MPA |
MPA |
2 |
2 |
Progress in Managing MPAs
The progress in implementing management measures for MPAs is summarised in Table 2. This includes information on where spatial management measures are in place and where they are under discussion. It also includes information on the number of MPAs that have been monitored by statutory bodies.
Table 2. Summary of progress in managing Marine Protected Areas in the Fladen and Moray Firth Offshore OMR .
|
Type of MPA |
No. of MPAs with spatial measures in place pre-2012 |
No. of MPAs with new spatial measures in place 2012-2018 |
No. of MPAs with spatial measures under discussion 2012-2018 |
No. of MPAs monitored by statutory bodies 2012-2018 |
No. of MPAs monitored by citizen scientists 2012-2018 |
|
Special Area of Conservation |
0 |
0 |
1 |
0 |
0 |
|
Nature Conservation MPA |
0 |
0 |
2 |
2 |
0 |
Progress is ongoing with fisheries management options being developed in the three MPAs, Central Fladen MPA, the Norwegian Boundary Sediment Plain MPA and the Scanner Pockmark SAC.
Progress in Monitoring MPAs
Information on the evidence base used to characterise the offshore MPAs in the Fladen and Moray Firth Offshore OMR and any subsequent monitoring is given in the Site Information Centre web page ( https://jncc.gov.uk/our-work/offshore-mpas/ ) for the following MPAs:
- Central Fladen MPA,
- Scanner Pockmark SAC,
- Norwegian Boundary Sediment Plain MPA.
Priority Marine Features
The assessments focus on individual/ grouped habitats and species with a number of case studies reflecting more detailed research and monitoring as outlined in ‘What is assessed’. A key component of an OMR is the number and type of Priority Marine Features (PMFs) present in the OMR and the associated protected areas. In addition, there is concern about invasive non-native species and the impact that they are having. With respect to these three aspects, the principal findings of SMA 2020 that are most relevant to the Fladen and Moray Firth Offshore OMR are summarised below.
Number of Priority Marine Features and birds (non-PMF) recorded
The Fladen and Moray Frith Offshore OMR is the location for a range of PMFs in Table 3.
Table 3. Summary of Priority Marine Features in the Fladen and Moray Firth OMR .
|
PMFs – grouped habitats and species |
No. of species/habitats recorded |
|
Intertidal and continental shelf habitats |
5 |
|
Fish |
24 |
|
Mammals (regularly occurring) |
10 |
|
Shellfish & other invertebrates |
2 |
|
Seabirds (non-PMF) - breeding |
0 |
|
Seaducks, grebes & divers (non-PMF) – non-breeding |
0 |
- There are 41 PMFs recorded in this region, including a range of fish, marine mammals and sedimentary habitats.
- Burrowed mud is an important marine habitat supporting a rich community of mainly burrowing species. The constant churning of the sediment through bioturbation provides the sediment with oxygen through the inflowing seawater, improves the breakdown of organic matter and releases nutrients back into the water. Longer-lasting burrows also provide shelter to other marine life from the starfish and sea urchins that patrol the muddy surface looking for food. Burrowed mud is considered by OSPAR to be a Threatened and/or Declining habitat across the North-east Atlantic.
- The burrowed mud provides habitat to the nationally scarce tall sea pen Funiculina quadrangularis, which can grow up to 2 m in height. Brittlestars such as the nationally rare Asteronyx loveni that appears to be an obligate commensal of the tall seapen, use it as an elevated perch from which to filter food from passing currents.
- Both the phosphorescent sea pen (Pennatula phosphorea) and the slender sea pen (Virgularia mirabilis) also occur in this habitat.
- Ocean quahog (Arctica islandica) is a bivalve species considered by the OSPAR Commission to be Threatened and/or Declining in the Northeast Atlantic. This thick-shelled clam can live for more than 400 years, making it one of the longest-living creatures on Earth. Like tree rings, the age of ocean quahog can be determined by counting the shell layers that form each year.
- This region contains Submarine structures made by leaking gases which consist of depressions in the seafloor called pockmarks which have been created by the expulsion of gases. Some of these pockmarks contain blocks of ‘methane-derived authigenic carbonate (MDAC), i.e. carbonate pillars and slabs made by anaerobic oxidation of methane (AOM) by a specialised community of microbial organisms. Other pockmarks have active methane seeps but no MDACs.
- The communities associated with the carbonate slabs and blocks are similar to reef and hard-substrate communities. Where soft sediment prevails, the communities appear to be more similar to wider soft sediment ecosystems. The nematode species Astomonema southwardarum, known to host endosymbiotic, chemoautotrophic bacteria within their body cavity was first described from the Scanner Pockmarks and occurs here with high abundance.
Climate change
There is good evidence that climate change is driving changes in the physical, chemical and biological conditions of the marine environment but the current evidence base limits the ability to draw conclusions at the scale of the individual marine regions, including Fladen and Moray Firth Offshore OMR. This is a combination of the lack of comprehensive spatial coverage of key monitoring programmes, the relatively short time series, and the complex linkages of climate change impacts in the marine environment.
Increasing concentrations of atmospheric greenhouse gases have caused more energy to be trapped within the Earth’s atmosphere, land and ocean. Approximately 90% of this excess energy has been absorbed by the ocean, resulting in warming ocean temperatures (see Temperature assessment and Climate change Sea temperature assessment).
The increasing concentration of carbon dioxide, one of these greenhouse gases, has the additional consequence of driving a reduction in the pH of the ocean, a process known as ocean acidification (see Ocean acidification assessment and Climate change Ocean acidification assessment).
Mean sea level is rising due to increased contributions of freshwater from melting of land-based ice (glaciers and the polar ice sheets) and due to thermal expansion of water (see Sea level and tides assessment and Climate change Sea level assessment).
The warming temperatures also result in lower oxygen concentrations due to the fact that warm water holds less oxygen and changes in stratification further influence oxygen concentrations (see Dissolved oxygen assessment and Climate change Dissolved oxygen assessment). Together with increased metabolic rates in organisms resulting in increased respiration, oxygen depletion has a severe impact on marine organisms due to the impact on metabolic processes.
These changes in the physical environment are also having an impact on marine life, such as changes to their metabolism, changes in seasonality and the timing of events in natural cycles, and changes in their distribution. These changes have consequences for the growth, survival and abundance of species, including those of commercial importance or critical to conservation objectives.
At present, most of these impacts are assessed at scales greater than SMR / OMRs. The Community Temperature Index combines species temperature affinity and their abundances. This index has the potential to inform how communities change due to climate change. An example of changes in the Community Temperature Index from bottom-living fishes can be found in the Fish section within Biological Impacts of Climate Change, where more information on other impacts in marine food webs can be found (such as seabirds and marine mammals) on large regional scales in Scottish waters.
Sea surface temperature in the Fladen and Moray Firth Offshore OMR has increased since 1870 by 0.06 °C per decade on average. The rate of increase has not been constant, and in the last 30 years (1988-2017), the rate of change in temperature was +0.16 °C per decade.
Detecting and understanding long-term change in biological time series is complex and resolving that which is due to climate change remains a challenge. Data from the Continuous Plankton Recorder (1980-2017; see Plankton Assessment) show significant increasing trends in the abundance of diatoms (and specifically pelagic diatoms) and meroplankton (those species who spend part of their life cycle in the plankton community). These data also show a decreasing trend in the abundance of large copepods. The increases in diatom and meroplankton lifeform abundance were correlated significantly to sea surface temperature, used as a proxy for climate change.
Summary
The Fladen and Moray Firth Offshore OMR has seen a 40% and 13% increase in the value of the fisheries catch in the Fladen Scottish Sea Area and in Moray Firth respectively over the five years from 2014-2018. Combined hydrocarbons production increased by 4% (i.e. 1 million tonnes oil equivalent) over the five years 2014-2018. Subsea active power cables length increased by 64km over the five years 2015-2019. There is currently 850MW offshore wind capacity awaiting construction and 1,116MW under construction.
The five main pressures affecting the OMR are Surface abrasion, Sub-surface abrasion/penetration, Removal of target species, Removal of non-target species, Litter. Other pressures identified are Hydrocarbon and PAH contamination, Introduction or spread of non-indigenous species, Physical change, Physical removal, Reduction in availability or quality of prey, Siltation rate changes, Synthetic compound contamination, Transition elements & organo-metal contamination and Underwater noise.
Contaminant (i.e. PAHs, PCBs, PBDEs and heavy metals) concentrations were generally above background but below concentrations where adverse effects could occur. Concentrations in sediment and biota were stable or declining for all measured substances. There is a relatively low concentration of microplastics in surface water and no consistent trend in seafloor litter density between 2012-2018.
Two new MPAs were designated between 2012-2018, and no new spatial management measures were put in place. Spatial fisheries management measures are under discussion for three MPAs. Two MPAs were monitored by statutory bodies during the period 2012-2018.
In the last 30 years sea temperature has risen by 0.16 °C per decade.