On the 23rd October 2015, JNCC, in partnership with the Centre for Environment, Fisheries and Aquaculture Science (Cefas), began a 14 day survey of Croker Carbonate Slabs Site of Community Importance aboard the Research Vessel (RV) Cefas Endeavour. Croker Carbonate Slabs is one of the 20 offshore candidate Special Areas of Conservation (cSAC) in UK offshore waters. The area is located in the Irish Sea, approximately 30km west of Anglesey.
Map showing the distribution of Annex I habitat “Submarine structures made by leaking gases” within the cSAC/SCI boundary. View and download spatial data for this MPA on the JNCC UK MPA interactive mapper © JNCC, 2015.
The site is designated for Submarine structures made by leaking gases, specifically methane-derived authigenic carbonate (MDAC). These carbonate blocks and slabs form when methane rising from deep below the seabed is consumed by microbes in the seabed sediment. The microbes create the carbonate, which acts as a cement, gluing sediment particles together to form a type of rock. The seabed habitats created by these MDAC structures support a diverse range of marine species that are absent from the surrounding seabed, which is characterised by coarse sediment. Large carbonate blocks support a diverse range of soft corals, erect filter feeders, sponges, tube worms and anemones, whereas the flatter, pavement-like MDAC structures are colonised with scour-resistant animals such as hydroids and bryozoans.
By Alice Cornthwaite