Location and physical characteristics
Figure 1: Hatton Offshore Marine Region. The thicker white line delineates the extent of the Hatton SMR / OMR. For a map of all SMRs and OMRs, see Figure 5 here
| Sea area (km2) | 155,215 |
| Deepest point (m) | 3,185 |
| Shallowest point (m) | 158 |
| Average depth (m) | 1,783 |
| Tides (m) | 1.8 – 2.4 |
| Salinity | 34.88 – 35.50 |
| Sea surface temperature (°C) | 8.5 – 13.1 |
The Hatton OMR is the westernmost OMR (Figure 1). It extends westwards from the western slopes of Rockall Bank into the Iceland Basin. The diverse seabed topography incudes Hatton Bank, a large elongate arc-shaped volcanic bank stretching nearly 500 km in length. The Bank rises to 1 km above the seafloor from the surrounding deep-water basin. Cold waters of Arctic origin (<3°C) fill the deep basins below about 800 m, intermediate waters lie between this cold deep water and the warmer Atlantic waters above.
Two strong flows occur on the western sides of the Hatton and Rockall banks, the Hatton Bank Jet and the Rockall Bank Jet, respectively. These two branches of the North Atlantic Current flow northwards, carrying warm, salty Atlantic water. The circulation patterns in this region are complicated and not well explored. The Overturning in the Subpolar North Atlantic Program (OSNAP; see also Circulation Assessment) is addressing this knowledge gap. The wave climate is influenced by conditions in the North Atlantic, with a large swell at times due to the long fetch.
Productive
Hatton Offshore Marine Region is the most westerly of all the marine regions. Hatton is incorporated in the International Council for the Exploration of the Sea (ICES) areas 6b and 12b. ICES area 12b sits to the west of area 6b (see fisheries assessment). The demersal assessment for area 6b falls mostly within Rockall OMR, with only a small proportion in the south-east corner of Hatton. The offshore marine regions are large areas that have been patchily sampled in space and time with respect to assessing the deep-sea fish community. This is a common issue in the deep sea due to the challenges involved in accessing these areas. In the deep-sea fish assessment, this patchy sampling has necessarily been extrapolated across the entire area of each of the deep-sea OMRs (Hatton, Rockall, Bailey and Faroe Shetland Channel). The notable gaps in sampling coverage include the deep regions of the Rockall Trough, the western reaches of the Bailey OMR and the entire Hatton OMR, other than the furthest south-east corner.
The productive assessment has been undertaken on a sectoral basis for a number of Sectors, including aquaculture, oil and gas, renewables and aggregates. There was only fishing activity within the Hatton OMR during the period 2014 – 2018 (Figure 2).
Figure 2: Changes that have taken place in the Hatton OMR by Sector.
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 Hatton 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 | Physical change (to another seabed type) |
|
||
| 2 | Removal of non-target species (including lethal) |
|
||
| 3 | Removal of target species (including lethal) |
|
||
| 4 | Surface abrasion |
|
||
| 5 | Sub-surface abrasion/penetration |
|
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 Hatton 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. Hatton is in the Atlantic North West Approaches biogeographic region. However, this region is not included in the MSS contaminants and biological effects sampling plan, due to difficulties sampling in these deep sea areas. In addition, there may not be suitable sediment and fish sites in this area. However, PCBs and PBDEs were previously measured in Scottish deep-water fish (black scabbard, roundnose grenadier and black dogfish) in the Atlantic North West Approaches region from 2006 and 2012 (Webster et al., 2014).
PCBs and PBDEs were detected, with PCB concentrations being above background but below concentrations where adverse effects could occur, confirming that these contaminants are transported to the Scottish deep- water environment by long range atmospheric transport where they accumulate to higher concentrations in species with the longest lifespans.
Marine litter
Due to the lack of assessment criteria for marine litter, status assessments were not possible. Seafloor litter was assessed at the scale of the biogeographic regions; Hatton OMR is included in the Atlantic North West Approaches biogeographic region. The evidence indicates that there are apparent decreases in seafloor litter density over time between 2012 to 2018 inclusive for the Atlantic North West Approaches.
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 Hatton OMR, including changes in distribution and extent.
Marine Protected Areas
Progress in developing the Scottish MPA network
There are 3 MPAs in the Hatton 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 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 Hatton 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 |
|
Candidate Special Area of Conservation |
cSAC |
1 |
1 |
|
Nature Conservation MPA |
MPA |
1 |
1 |
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 Hatton 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 |
1 |
0 |
1 |
0 |
|
Candidate Special Area of Conservation |
0 |
1 |
0 |
1 |
0 |
|
Nature Conservation MPA |
0 |
1 |
0 |
0 |
0 |
Fishing activities within the sites are managed by the North East Atlantic Fisheries Commission. The full extent of Hatton Bank cSAC has been closed to bottom fisheries since 2013. Two further areas are also closed to demersal fisheries outside the SAC boundary, one to the south east and one to the south west of Hatton Bank. In the North West Rockall Bank SAC, the measures currently in place are for a zoned closure to all demersal gears with a small portion of the site still open to fishing.
Progress in Monitoring MPAs
Information on the evidence base used to characterise the offshore MPAs in the Hatton 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:
- Hatton Bank cSAC,
- Hatton-Rockall Basin MPA,
- North West Rockall Bank SAC.
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 region 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 Hatton OMR are summarised below.
Number of Priority Marine Features and birds (non-PMF) recorded
The Hatton OMR is the location for a range of PMFs table 3.
Table 3. Summary of Priority Marine Features in the Hatton OMR .
|
PMFs – grouped habitats and species |
No. of species/habitats recorded |
|
Intertidal and continental shelf habitats |
7 |
|
Fish |
23 |
|
Mammals (regularly occurring) |
6 |
|
Shellfish & other invertebrates |
0 |
|
Seabirds (non-PMF) - breeding |
0 |
|
Seaducks, grebes & divers (non-PMF) – non-breeding |
0 |
- There are 36 PMFs recorded in this region, representing a range of fish species, marine mammals and deep-sea seabed habitats.
- The hard substrata provided by the boulders, cobbles and bedrock reef support a rich diversity of corals, including lace corals, black corals, soft corals, cup corals and gorgonian sea fans. Other species found include a range of sponges, sessile sea cucumbers, anemones and brachiopods.
- The Coral gardens found in the region are an OSPAR Threatened and/or Declining habitat.
The region includes unusual aggregations of deep-sea sponges, an OSPAR Threatened and/or Declining habitat. Two different types of deep-sea sponge aggregations are known to be present in the region; aggregations dominated by encrusting sponges, and bird’s nest sponge (Pheronema carpenteri) fields. Both types of deep-sea sponge aggregations act as biodiversity hotspots, with a range of other species associated with them, such as polychaetes, burrowing anemones, anemones, and crinoids.
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 Hatton 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 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 change in the Hatton OMR is highly variable. The time series trend is not statistically significant, and in the last 30 years (1988-2017), there was also no statistically significant trend observed.
Summary
The Hatton OMR has seen a 2187% increase in the value of the fisheries catch over the five years from 2014-2018, although the actual value is small at just over £1 million in 2018.
The five main pressures affecting the OMR are Physical change, Removal of non-target species, Removal of target species, Surface abrasion, Sub-surface abrasion/penetration. Other pressures identified are Death or injury by collision above water, Death or injury by collision below water, Litter, Siltation rate changes and Underwater noise.
No contaminant (i.e. PAHs, PCBs, PBDEs and heavy metals) samples were collected from the OMR due to difficulties of sampling. In the wider Atlantic North-west Approaches biogeographic region the evidence shows there is a decrease in sea-floor litter density between 2012-2018.
Two new MPAs were designated between 2012-2018, and new spatial fisheries management measures were put in place for three MPAs. Two MPAs were monitored by statutory bodies during the period 2012-2018.
In the last 30 years no statistically significant trend in sea temperature was observed.