Annex I Sandbanks in offshore waters

Annex I sandbanks slightly covered by seawater all the time occur where areas of sand form distinct elevated topographic features which are predominantly surrounded by deeper water and where the top of the sandbank is in less than 20 metres water depth. However, the sides of these sandbanks, can extend into deeper water up to 60m whilst still being considered the feature. Please refer to page 8 of The Interpretation Manual of European Union Habitats - EUR28 for the full and current EU definition of this Annex I habitat; this has been interpreted at a UK level and applied on a case by case basis at a local level for each offshore sandbank site.

 

Typical communities
The biological communities typical of sandbanks can vary greatly depending on sediment type and depth, as well as fine-scale physical, chemical and biological processes. Most notably, the interaction between oceanographic processes (such as waves, tides and currents) and the topography of sandbanks can have a profound influence on biological productivity (e.g. Scott et al., 2010) through the creation of internal waves that re-suspend organic material into the water column.

Communities found on sandbank crests are predominantly those typical of mobile sediment environments and tend to have low diversity. Fauna such as polychaete (cat worms) and amphipod (shrimp-like crustaceans) thrive in this environment as they are able to rapidly re-burry themselves. Animals like hermit crabs, flatfish and starfish also live on top of the sandbank.

Troughs or areas between banks generally contain more stable gravelly sediments and support diverse infaunal and epifaunal communities. Here sediment movement is reduced and therefore the areas support an abundance of attached bryozoans, hydroids and sea anemones. In the Southern North Sea, there have been frequent observations of biogenic reefs created by the Ross worm Sabellaria spinulosa  in association with sandbanks.

Sandbank termonology
Conservation Value

Due to enhanced levels of primary and secondary productivity on or around sandbanks, a range of fish species use sandbanks as feeding and nursery grounds; including sandeels (Ammodytes spp), dragonets (Callionymus spp), goby (Pomatoschistus spp), lesser weaver (Echiichtys vipera), European plaice (Pleuronectes platessa) and common dab (Limanda limanda) – making the conservation of sandbanks vitally important to the fishing industry. Foraging seals, cetaceans and seabirds may also be found in greater numbers in the vicinity of sandbanks due to their shallower nature, which enhances the availability of typical prey items (e.g. Daunt et al., 2008; Scott et al, 2010; Camphuysen et al., 2011; McConnell et al., 1999, Jones et al., 2013).

 

Types of sandbanks
Sandbanks can be categorised either by sediment type or by topography. The different sediments which can form Annex I sandbanks are sublittoral coarse sediments (EUNIS A5.1), subtidal mixed sediments (A5.4) and sublittoral sands and muddy sands (A5.2) with particles sometimes reaching the size of cobbles or boulders.

The different types of topographic sandbank are:

  1. Sandy mounds: created by glacial processes which have long since stopped acting on the feature. While surface sediments may be mobilised, the extent and distribution of the sandbanks as a whole remain broadly unaffected by ongoing hydrodynamic processes.
  2. Current tidal sandbanks: can be relatively mobile; their extent and distribution being actively influenced by ongoing hydrodynamic processes and subsequently changing naturally over time. Types of current tidal sandbank include:
    • Open shelf ridge sandbanks;
    • Estuary mouth sandbanks; or
    • Headland associated banks (Dyer and Huntley, 1999).

 

Distribution

JNCC maintain a map that shows areas of Annex I sandbank habitat. These are areas where JNCC believe that Annex I sandbank might be present. We also map the range in which Annex I sandbank could occur within UK waters. These are areas where JNCC believe that Annex I sandbank might be present, because the sediment type and depth of seabed fall within the sandbank definition.  To view data on Annex I habitats in UK waters and to download the shapefiles for these Annex I habitats, please see the JNCC UK Marine Protected Areas Interactive Map.  Through offshore survey, JNCC has confirmed the presence of Annex I sandbanks and continues to survey to better delineate their extent. . For information on the identification of Annex I sandbank SACs within 12 nautical miles of the coast, please contact the relevant country conservation agency.

Protected sites

SACs have been selected for sandbanks in UK waters to ensure that we have the full range of different sandbank types included in the SAC network. In offshore UK waters the majority of sandbanks are situated in the southern North Sea and therefore a higher number of cSACs for this habitat have been identified in that region than around the rest of the country (table 1).

 

Table 1 - List of SAC’s designated within UK offshore waters for the protection of Annex I Sandbanks. Further information available on each site by clicking on the link.
MPA Region Sandbank Type
Dogger bank cSAC/SCI Southern North Sea Sandy mound
Haisborough Hammond and Winterton cSAC/SCI Southern North Sea Headland associated, current tidal sandbanks
Inner Dowsing Race Bank & North Ridge cSAC/SCI Southern North Sea Headland associated, current tidal sandbanks, containing Sinusoidal sandbank
North Norfolk Sandbank and Saturn Reef cSAC/ SCI Southern North Sea Current tidal open shelf ridge sandbanks
Bassurelle Sandbank cSAC/SCI  Eastern English Channel Current tidal open shelf ridge sandbanks

 

 

Official definition

Literature:

The European Commission have published "Guidelines for the establishment of the Natura 2000 network in the marine environment" to better inform site selection for the marine habitats and species listed on the Habitats and Birds Directives. This includes further interpretation of the sandbank definition as laid out in the Directive.

JNCC have published 2 papers to support the application of the European Commissions’ guidelines in the UK and offshore waters specifically: 
Selection criteria and guiding principles for selection of special areas of conservation (SACS) for marine Annex I habitats and Annex II species in the UK. May 2009
Advice to support the implementation of the EC habitat and Bird directive in UK offshore Waters. JNCC report 325.

  • Collins, M.B., Shimwell, S.J., Gao, S., Powell, H., Hewitson, C. & Taylor, J.A. (1995). Water and sediment movement in the vicinity of linear sandbanks: the Norfolk Banks, southern North Sea. Marine Geology, 123, 125-142
  • Camphuysen, K., Scott, B. and Wanless, S. (2011). Distribution and foraging interactions of seabirds and marine mammals in the North Sea: a metapopulation analysis. Available online from: http://www.abdn.ac.uk/staffpages/uploads/nhi635/ZSLpaper-kees.pdf.
  • Daunt, F., Wanless, S., Greenstreet, S.P.R., Jensen, H., Hamer, K.C. and Harris, M,P. (2008). The impact of the sandeel fishery on seabird food consumption, distribution and productivity in the northwestern North Sea. Canadian Journal of Fisheries and Aquatic Science 65: 362-81.
  • Dyer, K.R. and Huntley, D.A. (1999) The origin, classification and modelling of sandbanks and ridges. Continental Shelf Research,19, 1285-1330.
  • Jones, E., McConnell, B., Sparling, C., Matthiopoulos, J. (2013). Grey and harbour seal density maps. Report from the Sea Mammal Research Unit to Marine Scotland. Available online from: http://www.scotland.gov.uk/Resource/0041/00416981.pdf
  • McConnell, B.J., Fedak, M. A., Lovell, P, and Hammond, P.S. (1999). Movements and foraging areas of grey seals in the North Sea. Journal of Applied Ecology 36: 573–90.
  • Scott, B.E., Sharples, J., Ross, O.N., Wang, J., Pierce, G.J and Camphuysen, C.J. (2010). Sub-surface hotspots in shallow seas: fine-scale limited locations of top predator foraging habitat indicated by tidal mixing and sub-surface chlorophyll. Marine Ecology Progress Series 408: 207-26