Offshore seabed survey of Turbot Bank possible MPA

This map presents the findings from analyses of the acoustic data and groundtruth samples gathered during the seabed survey of the Turbot Bank possible Marine Protected Area (pMPA). Turbot Bank lies within a coarse sandy sediment plain to the east of Scotland, approximately 65 km east of Peterhead on the Aberdeenshire coast, south of the Fladen Ground, and comprises a shelf bank and mound feature. The report describes the presence, location and extent of broadscale habitats, biotopes and Scottish Marine Protected Area (SMPA) Priority Marine Features within the Turbot Bank pMPA. Full coverage multibeam echosounder data (bathymetry and backscatter) collected under the Civil Hydrography Programme were available for the western half of Turbot Bank pMPA. During a dedicated survey in December 2012, new acoustic data were collected in the eastern part of the bank. Additionally, 102 grab samples, 27 videos and 742 still images were collected. Broadscale habitats were mapped employing the Object-Based Image Analysis software eCognition. Standard univariate and multivariate analyses on the taxon abundance data have been performed to identify distinct faunal assemblages. Multivariate analyses of the infauna and epifauna data was used to identify distinct clusters. EUNIS biotopes were then assigned to the clusters based on the presence of characterising species. The Turbot Bank pMPA is dominated by two broadscale habitats. These are A5.1 Subtidal Coarse Sediment, which occupies the shallowest parts of the bank and, to a lesser extent, A5.2 Subtidal Sand, which is typically associated with greater water depths on the flanks of the bank. Both broadscale habitats conform to the definition of the SMPA Priority Marine Feature Offshore Subtidal Sands and Gravels, which was present across the entire survey area.
Distinct spatial patterns using infaunal univariate metrics were not observed; however multivariate analysis revealed that infaunal assemblages are dominated by species characteristic of several biotopes found within the Offshore Subtidal Sands and Gravels Priority Marine Feature. Six infaunal stations, located on the flanks of Turbot Bank, have been assigned tentatively to the EUNIS Level 5 biotope A5.251: Echinocyamus pusillus, Ophelia borealis and Abra prismatica in circalittoral fine sand. However, the majority of infaunal stations could not be asigned any higher than EUNIS Level 3. Epifaunal assemblages across the shallowest part of Turbot Bank are typical of the EUNIS Level 5 circalittoral coarse sediment habitat A5.141: Pomatoceros triqueter with barnacles and bryozoan crusts on unstable circalittoral cobbles and pebbles. The mobile species of particular importance to the designation of this site, the sand eel Ammodytes sp., was identified at 14 of the 70 stations sampled by Hamon grab. No Annex I habitats were found at Turbot Bank pMPA.