Croker Carbonate Slabs

General site character

• Marine areas, Sea inlets (100%)
  

Annex I habitats that are a primary reason for selection of this site

• 1180 Submarine structures made by leaking gases

  The Croker Carbonate Slabs is an area in the mid-Irish Sea, approximately 30km west of Anglesey, where a total area of over 800 ha of the Annex I feature “submarine structures made by leaking gases” have been identified. The site lies in 70m water depth in the north descending down to approximately 100m at the south west corner. The seabed surface is composed of extensive areas of exposed methane-derived authigenic carbonate (MDAC). These MDAC structures range from ‘low relief’ (elevation of up to 20cm above the surrounding seabed) to ‘high relief’ (elevation over 20cm above the surrounding sediment, and often up to 2m). The seabed habitats created by these MDAC structures are distinctive, supporting a diverse range of marine species that are absent from the surrounding seabed characterised by coarse sediment. Areas of ‘high relief’ MDAC support a diverse range of soft corals, erect filter feeders, sponges, tube worms and anemones whilst the ‘low relief’ MDAC is colonised with scour-resistant hydroids and bryozoans. The surrounding sediment is highly mobile and consists of poorly sorted sand (from fine to coarse grained) with a large proportion of broken shell gravel and whole shells interspersed with rippled sand. A blue-grey clay was also commonly seen towards the southern end of the site.

Annex I habitats present as a qualifying feature, but not a primary reason for selection of this site

• Not Applicable

Annex II species that are a primary reason for selection of this site

• Not Applicable

Annex II species present as a qualifying feature, but not a primary reason for site selection

• Not Applicable