Habitat mapping in the Adriatic (Mediterranean Sea): approaches and methodologies for assessing seaoor habitat from coastal areas to deep sea

The in-depth knowledge of habitat attributes is central for the proper management of the marine system and must unavoidably rely upon the adequate representation of all physical and biological typologies. Historically, a number of  concepts and methods dealing with marine habitat classification and mapping have been developed, often singling out a specific discipline by large from life sciences. In the framework of the E.U. COCONET project (Towards COast to COast NETworks of marine protected areas from the shore to the high and deep sea) we set forth a unified approach on the definition of habitats. Our scheme combines multi-scale geological and biological data. The goal is to identify, describe and map habitat distributions from shallow coastal waters to deep sea in a consistent way. We particularly highlight the strict relation between the geological/geomorphological features and the biological component and the need of tools for data integration and management. The Adriatic Sea provides a suitable ground where to test the new classification scheme because of the variety of habitats and the complexity of its submerged landscape.

The Adriatic Sea is a narrow epicontinental basin (ca. 200×800 km) located in the central Mediterranean Sea, divided into three sub basins: the northern Adriatic, a broad shelf with depths shallower than 100 m, connected to the Lagoon of Venice, the biggest in the Mediterranean Sea, the middle Adriatic shelf basin, hosting the 270-m deep Jabuka/Pomo Pit, and the Southern Adriatic basin, with a depression reaching down to 1200 m towards the Ionian Sea. Furthermore the Adriatic is also one of the major sites of dense water formation in the Mediterranean basin. Because of the interaction of such topographic and hydrological features, the Adriatic Sea is rich of relevant benthic habitats, from shallow-lagoonal oyster-reefs and sponge aggregates in the lagoon of Venice, to shallow subtidal coralligenous formation on the north and south continental shelf, up to deep sea cold-water coral and sponge assemblages at bathyal depths in the south. We mapped the entire basin at mesoscale using multi beam and backscatter data to derive habitat maps as a combination of geomorphological and substrate level. In significant areas, such as the Bari Canyon, we produced both mesoscale maps combining the three levels (Fig. 1) and microscale maps analyzing and classifying the ROV track lines, image coming from drop frame camera and sediment samples .

Working at different scales and in different seafloor settings, we need to adapt the existing methods and to redraw new solutions to obtain results consistent with the knowledge of both biological and sedimentological processes. Here, we present the approaches and methodologies developed to map benthic habitat for various case studies, from shallow water to deep sea applied to different scales.