The Scanner pockmark complex in the south of the site is a large
seabed depression of approximately 320,000m2 containing
two deep areas reaching approximately 17m below the surrounding sea
floor. Carbonate blocks known as ‘submarine structures made by leaking gases’ – a
listed habitat under Annex I of the EC Habitats Directive – have
been recorded in the base of these pockmarks. Carbonate blocks form
when methane is released from the seabed and reacts with the
surrounding seawater. The pockmark sediment provides habitat for
the phosphorescent sea pen Pennatula phosphorea, slender
sea pen Virgularia mirabilis and tube anemone
Cerianthus lloydii and the carbonate structures in the
base of the pockmark support animals usually associated with rocky
reef, such as squat lobsters Munida sp., anemones and
fish. Chemosynthetic organisms are also present feeding off the
bubbling methane with the gutless nematode Astomonema
southwardorum, thought to occur only at the Scanner pockmark
The northern section of the site contains the Scotia pockmark
complex with two deep sections and active methane seeps. These
large pockmarks reach a depth of approximately 15m below the
surrounding sea floor.
Specific information on the conservation objectives relating to
this SAC is provided in the Conservation Advice
The diagram below is a summary of the key milestones involved in
the selection and designation of Scanner Pockmark SAC. More detail
can be found within the relevant documentation listed below.
The documents referred to below and any other
historical documents relating to Scanner Pockmark were produced
during the selection and designation process and therefore may be
out of date. This Site Information Centre is the most up to date
source of information for this MPA, and will reflect any additional
information gathered since these documents were produced.
The site contains 61 pockmarks of varying sizes. Four of these
are unusually large and occur in two pockmark complexes: Scanner
pockmark complex in the south of the site and the Scotia pockmark
complex in the north.
The Scanner pockmark complex comprises of two large pockmarks
with a combined area of approximately 320,000m2
and depths of up to 16.7m below the surrounding sea floor. These
pockmarks have a considerably greater volume than more typical
pockmarks in the vicinity of the site. The pockmarks were created
by the expulsion of shallow methane gas and have been maintained by
active gas seepage. At the base of the pockmarks, blocks of
‘methane derived authigenic carbonate’ (MDAC) have been recorded.
These carbonate rocks, formed by the precipitation of calcium
carbonate and cementation of the surrounding sediment, have been
identified as ‘submarine structures made by leaking gases’ - a
listed habitat under Annex I of the EC Habitats Directive. The
location and extent of carbonate blocks has not been precisely
mapped. However, the latest survey data from 2012 pointed to areas
of high acoustic reflectance within the pockmarks, suggesting the
presence of a hard substrate. These require further investigation
to examine whether they represent MDAC, shell hash or variations in
sediment particle size.
There is some evidence of chemosynthetic bacteria in the Scanner
pockmark which grow by oxidising sulphur and may support some of
the site’s other notable fauna. The most important species in the
pockmark from a conservation perspective is the gutless nematode
Astomonema southwardorum, which may derive some of its
nutrition from chemosynthetic bacteria. The Scanner pockmark is the
only known locality for this species found to date. Other important
species associated with the gas seepage in the pockmark are the
bivalves Thyasira sarsi and Lucinoma borealis.
The structures and pockmark depression attract fish species such as
Myxine glutinosa, four-bearded rockling Rhinonemus
Melanogrammus aeglefinus and Norway
redfish Sebastes viviparus on top of the carbonates
fish Anarhichas lupus in cavities underneath.
Conspicuous invertebrates at the site include Anthozoans such as
phosporescent sea pen Pennatula phosphorea,
sea pen Virgularia mirabilis and tube
anemone Cerianthus lloydii in pockmark sediment and
sea anemone Bolocera tuediae, Dahlia
anemone Urticina felina and plumose
anemone Metridium senile on the carbonate
The Scotia pockmark complex is composed of two deeper sections
with active methane seeps. The Northern Scotia pockmark is
approximately 76,000m2 in size with a depth of 12m below
the level of the surrounding seabed. The Southern Scotia pockmark
is at least 72,400m2 with a depth of 14.5m. Numerous
surveys since the 1990s have found evidence for the active seepage
of methane in this complex, but the presence of carbonate blocks
has not been confirmed. The latest survey data suggest that small
patches of harder substrate do occur within the Scotia pockmarks,
but whether these represent MDAC requires further confirmation.
Scanner Pockmark is one of three sites identified for protection
of Annex I Submarine structures made by leaking gases in the
UK. Braemar Pockmarks SAC also contains this
feature and is found 80km north-east of Scanner Pockmark. While
both sites are characterised by the presence of carbonate
structures, Scanner Pockmark has a slightly less diverse biological
community and less varied morphology. As there are few cases of
this Annex I habitat in the UK, both sites make important
contributions to the sufficiency of the UK MPA network for this
Further detail on the evidence for this SAC can be found on the
Site location: Coordinates for this
SAC can be found in the Natura 2000 Standard Data Form listed in
the Relevant Documentation.
Site area: 3.35 km2
Site depth range: Depth at the site
ranges from 150m below sea level down to 165m below sea level at
the base of the pockmark.
Charting Progress 2 Biogeographic Region:
Northern North Sea
Site boundary description
The boundary for
Scanner Pockmark is a simple polygon enclosing the minimum area
necessary to ensure protection of the Annex I habitat. Coordinate
points have been positioned as close to the edge of the interest
feature as possible. As bottom trawling is a significant threat to
the interest feature, the proposed boundary includes a margin to
ensure its protection.
Information for this site summary was adapted from the SAC
Selection Assessment Document and incorporates any further
information gathered since this document was produced. Please refer
to this document in the relevant documentation
section for further details and information sources.
Site specific data
There is a range of
data that underpin this SAC. The full overview of the data used to
support site identification along with information on confidence in
feature presence and extent is available in the Scanner Pockmark
All data that can be made publicly available are displayed on
the JNCC Interactive MPA Map.
Some of the data for this SAC has been collected through JNCC
funded or collaborative surveys and some through other means. These
data provide direct evidence confirming the presence of the
protected features within the site.
Survey and data
Data analysis reports
Analyses of data gathered as part of the surveys listed above,
as well as other relevant data analysis products, are available via
the following reports. Note the citations given are fully
referenced in the ‘additional relevant literature’ section
- Offshore seabed survey of Braemar Pockmarks and Scanner
Combined analysis of acoustic data and
video, still image, biological and sediment data for
ground-truthing is underway for the 2012 survey mentioned above and
reporting will be made available in due course.
Map displaying the MPA and
relevant underpinning data
- Geological investigation of pockmarks in the Scanner
Pockmark SCI area - 2015
JNCC commissioned the
British Geological Survey to compare 2012 survey data and earlier
geological data to assess changes in pockmark morphology and
condition. The study confirmed the presence of 61 pockmarks within
the site, four of which measured over 72,000 m2 with a
depth of greater than 12 metres compared to the surrounding seabed.
Comparison of acoustic data between 2001 and 2012 surveys revealed
that some pockmarks are becoming filled in with sediment,
believed to be the result of collapsing pockmark sidewalls. Strong
acoustic reflections shown in multibeam backscatter data suggest
that the muddy sea floor is punctuated with patches of harder
substrate in nearly half of the pockmarks. These require further
investigation (such as through visual observation or seabed
sampling) to determine whether they are examples of carbonate
blocks, shell fragments or a change in sediment particle size.
- Seabed fluid flow: the impact on geology, biology and
the marine environment - 2007
A review of survey data and associated studies by Judd and Hovland
(2007) indicates that the volume of the Scanner and Scotia
pockmarks is approximately 1 million m3 and they are
deep enough to cut through surrounding sediments, revealing stiffer
clay beneath. These pockmarks are larger and deeper than those
found nearby. The largest carbonate block observed in Scanner
pockmark measured 2 x 1 metre and was 20-50 centimetres thick.
- A review of pockmarks in the UK part of the North
Sea - 2001
Dando (2001) reviewed data from a 1989 survey in which grab samples
were taken to characterise the sediment, including chemical and gas
composition, and 1990 and 1991 surveys in which a manned
submersible was deployed to study infauna, taking 18 box-core
sediment samples. These surveys found that the macro-infauna of
Scanner pockmark was similar to that of the surrounding area, with
the exception of the bivalve Thyasira sarsi which was
confined to sulphur-rich sediments. The micro-infauna was dominated
by the gutless nematode while anthozoans were the most conspicuous
epifauna, found at higher densities in the pockmark than in
- Pockmarks in the UK Sector of the North Sea -
Preliminary analysis by Judd (2001) of acoustic records including
sidescan, backscatter and bathymetry taken during a 2001 survey of
petroleum block 15/25. Gas seeps and carbonate blocks were
identified in this area of the North Sea.
- Pockmark formation and activity in UK block 15/25,
North Sea - 1994
Seismic data from surveys in 1983, 1989, 1990 and 1991 found
evidence of gas plumes on the seabed and gas accumulations at
shallow depths beneath the seabed. The study by Judd et
al. (1994) estimates that the Scanner pockmark was formed
13,000 years ago.
- Ecology of a North Sea pockmark with an active methane
seep - 1991
Analysis of grab samples collected on two 1989 surveys by Dando
et al. (1991) found that the pockmark fauna was
characterised by the gutless nematode and the bivalve Thyasira
sarsi, which was confirmed to be feeding on chemosynthetic
bacteria. The chemical composition of samples suggested sediment
displacement had taken place – a feature of typical feature of
- Characteristics of two natural gas seepages in the
North Sea - 1985
Hovland and Sommerville (1985) describe the discovery of the
Scanner pockmark from acoustic and seismic records taken during a
routine environmental survey by the petroleum industry in 1983.
Acoustic data indicated the presence of an active seep in the form
of gas bubbles, low density liquid or suspended sediments.
Further supporting scientific literature consulted during the
identification of this site can be found in the Selection
References and Additional relevant
Please be aware that although these
sources contain information which is of interest in relation to
this MPA, they do not necessarily represent the views of JNCC:
- Judd, A.G. and Hovland, M. (2007). Seabed fluid flow: the
impact on geology, biology and the marine environment.
Cambridge: Cambridge University Press.
- Holmes, R. and Stoker, S.J. (2005). Investigation of the
origin of shallow gas in Outer Moray Firth open blocks 15/20c and
15/25d. Report to the Department of Trade and Industry No.
A review of data from British Geological Society regional surveys
and commercial data showing that gas is seeping from the seabed in
the Scanner and Scotia pockmarks and that these are unusually large
pockmarks compared to others in the surrounding area. Methane
derived authigenic carbonate is documented in both.
- Dando, P.R. (2001). A review of pockmarks in the UK part of
the North Sea, with particular respect to their biology.
Technical report produced for Strategic Environmental Assessment –
SEA2. Department of Trade and Industry Technical Report No.
- Judd, A.G. (2001). Pockmarks in the UK Sector of the North
Sea. Technical report produced for Strategic Environmental
Assessment – SEA2. Department of Trade and Industry Report No.
- Judd, A., Long, D. and Sankey, M. (1994). Pockmark
formation and activity, UK block 15/25, North Sea. Bulletin of
the Geological Society of Denmark 41:34-49.
- Dando, P.R., Austen, M.C., Burke, R.J., Kendall, M.A.,
Kennicutt, M.C., Judd, A.G., Moore, D.C., O' Hara, S.C.M.,
Schmaljohann, R. and Southward, A.J. (1991). Ecology of a North
Sea Pockmark with an active methane seep. Marine Ecology
Progress Series 70:49-63.
- Hovland, D.M. and Sommerville, J.H. (1985). Characteristics
of two natural gas seepages in the North Sea. Marine and
Petroleum Geology, 2 (4):319-326.
If you are aware of
any additional information not referred to in any of the
relevant documentation listed on the main page,
please contact JNCC.
MPA Conservation Advice
objectives set out the desired state for the protected feature(s)
of an MPA. The conservation objective for the protected feature of
the Scanner Pockmark SAC has been set based on knowledge of the
condition of the protected feature at the time of writing. Further
information on feature condition and the conservation objective is
provided in the Scanner Pockmark
conservation objectives and advice on
This information is useful if you are:
- preparing Habitats Regulations Assessments (HRAs) of proposed
plans or projects that may affect the site;
- planning measures to maintain or restore the site and its
- monitoring the condition of the qualifying features; or
- developing, proposing or assessing an activity, plan or project
that may affect the site.
The conservation objective for the protected feature of the MPA
Subject to natural change, restore the
submarine structures made by leaking gases to
condition, such that:
- the natural environmental quality is restored
- the natural environmental processes are maintained
- the extent, physical structure, diversity, community structure
and typical species representative of the submarine structures made
by leaking gases in the Northern North Sea are restored.
JNCC is working to provide more detailed advice on the
relatively broad, high level conservation objective listed above.
This supplementary advice will be posted here as and when it
Advice on operations
In line with
Regulation (18) of the Offshore Marine Conservation (Natural Habitats,
& c.) Regulations 2007 (as amended) which apply to the UK’s
offshore marine area, the
advice on operations for the protected feature of Scanner
Pockmark SAC outlines current knowledge of the nature and extent of
activities taking place which may have a significant impact on the
feature for which the site has been selected.
The advice on operations is based on JNCC’s scientific knowledge
of the biological communities present at the time of writing and
their sensitivities to pressures. For the most up-to-date
information about the biological communities present within the
site and their spatial distribution, please see the
evidence tab. Sensitivity information for
biological communities identified within the site can also be found
on the MarLIN website.
JNCC also provides a list of activities occurring within the
site and information on activity management in the
activities and management tab. This information is
also useful when assessing an activity, plan or project which may
affect the protected features and JNCC has provided this to aid the
cumulative assessment of impacts of human activities within the
site. While every attempt has been made to ensure this information
is accurate and kept up-to-date, the list is not to be considered
exhaustive or definitive. The list does not, for example, include
activities occurring off-site which may also be capable of
affecting the protected features.
The information contained within the advice on operations,
activities and management tab,
evidence tab, and MarLIN’s
sensitivity assessments are useful if you are:
- carrying out any activity that may impact the site and need to
find out how to operate within the law;
- an authority providing advice on specific proposals;
- an authority responsible for putting management measures in
Our scientific understanding of the ecology of the site, its
integrity and its qualifying features and how activities can affect
them may change over time. JNCC’s conservation advice will be kept
under review and will be periodically updated to reflect this and
surveillance required under Article 17 of the Habitats Directive. Conservation advice for
sites which straddle the 12nm boundary will continue to be
developed jointly with the relevant country nature conservation
body. Further information on JNCC’s conservation advice work is
available on the offshore MPA conservation
Activities known to be currently occurring within this
(Activities information correct as of April
- Oil and gas – two abandoned, explorative oil
wells occur within the site. The south-east corner of the MPA
overlaps with the Blenheim oil field (production
Existing licensed activities that take place within the
Scanner Pockmark SAC will continue to be managed in
line with relevant legislation and application processes by the
competent authorities. Further information on JNCC's
role in the provision of advice for licensed activities in the UK
offshore area is available on the offshore
industries advice webpages.
Mobile demersal otter trawling is the predominant activity in
the Scanner Pockmark SAC. There is little evidence of non-UK
registered vessels operating in the site.
Currently there is no site-based fisheries management within
this SAC. This site falls outside the UK’s 12 nautical mile limit
and so the site is to be managed under the
EU Common Fisheries Policy (CFP). Scottish Government has
developed a management
measures proposal which is due to be submitted to the European
Commission, these proposals include the removal of all bottom
contacting gear activity overlapping the site. Marine Scotland will
be the lead authority regarding implementation and compliance of
A stakeholder workshop was held on the 11th June 2013. The event
was organised by Marine Scotland (with support from JNCC) and
attended by relevant stakeholders from the Scottish industry
(Scottish Fishermen’s Federation). A
Fisheries Options Paper was prepared by JNCC and presented at
the workshop. Based on available VMS data, there was little
evidence of activity from non-UK fishing interests in the area. The
primary purpose of the workshop was to initiate the development of
management measures proposals for the Scanner Pockmark and Braemar
Pockmarks SAC sites.
In accordance with Article 18 of the revised CFP, requests for
management were developed jointly between the UK Government and the
other Member States with a direct management interest in the area.
The draft recommendation was presented to the North Sea Regional
Advisory Council’s Demersal Working Group in November 2013. The
final recommendation is due to be submitted to the European
- Shipping – There is low density of commercial
shipping in this area and due to its offshore location, vessel
anchorage is unlikely.
Under international law, ships have a right of passage at sea
including in areas designated as MPAs (unless management specifies
the restriction of ship transiting as outlined through an
International Maritime Organisation measure). The pressures
associated with shipping activity within Scanner Pockmark SAC are
not considered likely to impact the protected feature of the
Management Plan: JNCC is undertaking a review
of management plan requirements for offshore MPAs. Further detail
will be provided at a later date.
For information on management actions being taken forward for
this site, please go to
Marine Scotland’s Fisheries Management in Offshore SACs
Management Group: None at present
Further information on activities and feature sensitivity to
these pressures can be found under the Conservation
JNCC is currently leading on the development of a strategy for
biodiversity monitoring across all UK waters, to include MPA
monitoring. For MPAs, data and evidence collected from monitoring
activities will aim to:
- enable assessment of condition of the features within
- enable assessment of the degree to which management measures
are effective in achieving the conservation objectives for the
- support the identification of priorities for future protection
and/or management; and,
- enable Government to fulfil its national and international
assessment and reporting commitments in relation to MPAs and help
identify where further action may be required.
Information on monitoring of this MPA will be provided when it
Assessments of the condition of designated features in offshore
MPAs are required to report against our legal obligations. Ideally
these assessments should be based on observed data, and then
measured against targets for predefined indicators. However, for
MPAs in offshore waters we do not always have the appropriate
information to be able to do so. This is particularly true for
seabed habitats, which are the main type of feature designated for
protection in offshore MPAs.
To address these challenges, JNCC has been an active partner in
the development of new approaches and tools for the assessment of
habitats and species for a variety of national and international
status reports. They include the second cycle of the Conservation Status Assessment reports
under the EU Habitats Directive, Charting Progress 2
(CP2) and the OSPAR Quality Status
Report (QSR). JNCC continues to develop and pilot tools for the
assessment of marine habitats and species in offshore waters to
improve the quality and transparency of our offshore MPA
assessments, and contribute to the monitoring of marine
biodiversity in UK waters. These tools cover methods for producing
interim assessments of site features and their responses to
pressures, as well as developing more robust indicators for
determining condition of the features.
Every six years, Member States are required under Article
17 of the EU Habitats Directive to report on the Conservation
Status of Annex I habitats and Annex II species on the Habitats
Directive. The assessments should consider the habitat or
species both within the Natura 2000 network and in the wider
sea. The latest report was submitted by the UK in 2013
and provided a second assessment of the conservation status of
relevant habitats and species within UK marine waters during
2007-2012. . The next report is for the period 2013-2018 and is due
in 2019; information on the condition of features within SACs will
make a contribution to this report.
The assessments of features within MPAs will also feed into six
yearly reports on the state of the marine environment under the
Marine Strategy Framework Directive (MSFD),
which aims to achieve Good Environmental Status (GES) by 2020.