The coralligenous is a very complex habitat where crustose coralline algae (CCA) and red algae belonging to the order of Peyssonelliales are often the main bioconstructors in shallower waters, generating a new solid substrate and constituting a three-dimensional biogenic build-up. Coralligenous outcrops, mosaicking coarse biogenic sediments, dominate the seafloor. The Brindisi site is placed on a flat continental shelf, about 10 km far from the coast at an average depth of 30 m. In this perspective, the UHI may prove useful in habitat mapping to meet the requirements of European programs (e.g., EU MSFD). Our study targets the distribution and extent of two biogenic habitats (CWC and Coralligenous), in different geomorphological and depth contexts, considered to be of key importance in monitoring plans. At present, the Adriatic Sea is under siege by a number of stressors, such as high demographic pressure on its coastal areas, pollution, marine littering and dumping, fishing practices, ship traffic, harbour activities and industrial operations. The semi-enclosed Adriatic Sea hosts a variety of benthic habitats, including the shallow oyster reefs and sponge communities in the Venice Lagoon, coralligenous formations on the shelf (e.g., with references therein), down to the CWC habitat in deep water (> 200 m) in the south (e.g., ). Īs a first application to the Mediterranean basin, we tested the UHI in the Adriatic Sea. Laboratory experiments to measure changes in the health status of CWCs exposed to hydrocarbons emissions is another application of UHI. Underwater hyperspectral imaging with ROV has been used to study coastal kelp forests, vertical rock wall habitat and soft sediments, red calcareous algae and associated fauna, deep-sea megafauna and CWC communities. However, the most reported UHI application is within the field of benthic habitat mapping, modelling and monitoring. Among the many applications, UHI was related to the identification of manganese nodules, infrastructure inspection, seafloor impact of offshore drilling and marine archaeology. The UHI has been tested and utilized for different purposes from shallow (< 6 m) to abyssal depths (ca. Recently, different instrument carriers for the underwater hyperspectral imager (UHI) have been used in underwater field applications, such as the customized scanning rig, remotely operated vehicle (ROV) or autonomous underwater vehicle (AUV). To fulfill these requirements, there is a need for innovative approaches and tools to obtain detailed, reliable, quantifiable and repeatable maps of relevant habitats in different underwater environments. This effort is translated into quantifiable operational indicators that should be measurable at different scale and repeatable in time. The MSFD scope is to assess the good environmental status (GES) of European water with the lowest possible impact on the seafloor. Recently, the European programs such as the EU Marine Strategy Framework Directive (MSFD: 2008/56/EC), require the monitoring of benthic habitat extent and distribution (Criteria 1.4 and 1.5 of the Descriptor 1 “Biological Diversity”). The analysis of video and images is performed manually by expert interpretation, or automatically when a photomosaic is available. Traditionally, underwater habitat mapping has been carried out coupling acoustic remote sensing techniques with red/green/blue (RGB) images, videos and bottom sampling. Despite some technical problems, the first results demonstrate the suitability of the UHI camera for habitat mapping and seabed monitoring, through the achievement of quantifiable and repeatable classifications. We applied the spectral angle mapper (SAM) supervised classification to map the areal extent of the Coralligenous and to recognize the major CWC habitat-formers. We created a spectral library for each site, considering the different substrates and the main OOI reaching, where possible, the lower taxonomic rank. For the first time, we tested this system at two sites in the Southern Adriatic Sea (Mediterranean Sea): the cold-water coral (CWC) habitat in the Bari Canyon and the Coralligenous habitat off Brindisi. The aim of the project is to evaluate the potential of this instrument for mapping and monitoring benthic habitats in shallow and deep-water environments. Although this is a well-established technology for the study of subaerial environments, Ecotone AS has developed an underwater hyperspectral imager (UHI) system to explore the properties of the seafloor. Hyperspectral imagers enable the collection of high-resolution spectral images exploitable for the supervised classification of habitats and objects of interest (OOI).
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