Combined use of optical (satellite imagery), and acoustic (sidescan sonar) remote sensing techniques, as well as in situ methodologies (visual census; SCUBA diving, Towed Underwater Cameras, and Remotely Operated Vehicles) was employed to map the spatial distribution of seagrass habitats in the coastal waters of the Hellenic territory. Seagrass meadows were recorded at approximately 70% of the Hellenic coastline (Eastern Ionian, Aegean and Levantine Seas), and their surface area exceeded 2,673.1 km2. Posidonia oceanica is -by far- the dominant seagrass species of the Hellenic seas, covering the vast majority of seabed at depths between the shoreline and 25 – 30 m (or deeper in insular areas), followed by the species Cymodocea nodosa, Zostera noltei, and Halophila stipulacea, which, however, presenting local presence and limited areal extent. Habitat suitability in terms of the seabed spatial extent that is available for the growth of seagrass meadows (i.e., the spatial extent of coastal areas between the shoreline and the isobath of 20m) and the seawater clarity conditions are highlighted as the critical factors for the formation of well-structured and extensive meadows. The results of this study are of great importance and usefulness for the effective management and conservation of valuable marine ecosystems. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications.

-Marine habitat mapping using sonar data -Area: Lipsi island -Main attribute: Seagrass -Data source: archipelagos institute of marine conservation -Map resulting from survey (kayak sonar survey) and processed using interpolation algorithm

Envision have undertaken a biological interpretation of the geophysical data from Tranche A and Creyke Beck Export Cable Route. The strategy for this interpretation was to integrate sample records and the geophysical remotely sensed images to produce distribution maps. This follows the strategy that has been established within the EU through the MESH program. The primary purpose of analysis was to derive a limited range of habitat classes suitable for ground truthing the acoustic data, which were adopted as the mapping units. The requirements for successful ground truthing are not exactly the same as describing diversity. There has been more emphasis on commonality and potential for overlap between the mapping units. The analyses identified a small number of robust classes from the infauna defined by their predominant species and those that contributed most to the classes distinctiveness. Information on epifauna and gravel/cobble were incorporated to derive a single ground truth dataset Suitable ground truth data assigned to habitat classes is vital for integrated analysis and this necessitated Envision undertaking the analysis of the sample records to derive a locally relevant list of habitat classes. The analyses identified a small number of robust classes from the infauna defined by their predominant species and those that contributed most to the classes distinctiveness. Information on epifauna and gravel/cobble were incorporated to derive a single ground truth dataset The faunal composition of these groups were then matched to the Marine Habitat Classification for Britain and Ireland (v04.05) and a suite of possible biotopes assigned to the ground truth data. The geophysical data required processing and transformation to render the images suitable for integrated analysis. The analyses have been reported and the full list of habitat classes described. The interpretation of the geophysical data through integrated analysis with the ground truth data has been reported and the habitat class distribution map has been presented. Surficial sediments were identified from the still images and classified. These data have been used to ground truth the geophysical images and a map has been generated. The distribution of the habitats is discussed. The biota is typical of moderately exposed (moderately disturbed) gravelly sandy sediments in the North Sea. Although all the habitats can be considered components of Annex 1 Subtidal Sandbanks, there are no biotopes of particular sensitivity and, although Sabellaria spinulosa was found, the densities of individuals in samples was never very high and it is unlikely that any sample sites could be classified as biogenic reef.