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Mapping of coralligenous banks was carried out along the continental shelf of the northern and western margin of Sardinia Island (Italy, western Mediterranean Sea) in the context of the European Marine Strategy Framework Directive (MSFD, 2008/56/EC). Coralligenous banks are bioconstructions produced by calcareous coralline algae. Seafloor mapping was carried out through multibeam echosounder surveys and video transects, using a Remote Operating Vehicles (ROV), in areas not formerly explored. A high-resolution digital model of the seabed (DTM) was obtained from multibeam data. A total surface of 436 km² of sparse patches of coralligenous banks was mapped in the depth range ~40-160 m. A final map of coralligenous habitat distributions along the western and northern continental shelf of Sardinia (scale 1:250,000) was produced. The base-map is formed by the shaded DTM of the seabed. Other mapped features include the edge of the continental shelf and the distribution of rocky seabed. [ABSTRACT FROM AUTHOR]

The inner continental shelf is regarded as a repository of hyperpycnal flow (HF) deposits the analysis of which may contribute to hydrogeological risk assessment in coastal areas. In line with the source to sink paradigm, we examined the dynamics of the coastal watersheds facing the Salerno Gulf (Southern Tyrrhenian Sea) in generating hyperpycnal flows and investigated the shallow marine sediment record to verify their possible occurrence in the recent past. Thus, the morphometric properties (hypsometric integral, hypsometric skewness, hypsometric kurtosis, density skewness and density kurtosis) of the watersheds together with the potential rivers' discharge and sediment concentration, calculated by applying altitude- and extent -based experimental relations, allowed to detect the rivers that were prone to producing HFs. In the shallow marine environment record of the last 2 kyr, anomalous sedimentation, possibly linked to HF events, was identified by comparing the sand-mud ratio (S/M) down-core —at three sites off the main river mouths — to the expected S/M calculated by applying the relation governing the present-day distribution of sand at the seabed in the Salerno Gulf. A return period of major HF events ≤ 0.1 kyr can be inferred for rivers which fall into the category "dirty rivers". In these cases, the watersheds have a hypsometric index ranging between 0.2 and 0.3, coastal plains not exceeding 30% of the entire catchment area and a maximum topographic height ≥1000 m. A return period of about 0.3 kyr has been inferred for the "moderately dirty rivers". In these other cases, about 50% of the watersheds develop into a low gradient coastal plain and have a hypsometric index ranging between 0.09 and 0.2. The observations on land and offshore have been complemented to reach a more comprehensive vision of the coastal area dynamics. The method here proposed corroborates the effectiveness of the source to sink approach and is applicable to analogous sediment records in temperate continental shelves which encompass the last 3 kyr, a time interval in which the oscillations of relative sea level can be overlooked. [ABSTRACT FROM AUTHOR]

Abstract: Morphological and seismic–stratigraphic features of the Augusta Bay (offshore eastern Sicily) have been characterized by means of Sub-bottom Chirp profiles, Multibeam data and Side Scan Sonar images, covering an area of about 110km2. The marine data set was combined to mainland stratigraphy, derived from coastal boreholes and geological maps, to achieve a land–sea correspondence of main morpho-structural and stratigraphical features. The study area is located in the western sector of the Ionian Sea which represents a key area to reconstruct the geological parameters that control the processes of convergence between Africa and Europe in the Mediterranean. In particular, the area of interest draws the attention for problems concerning high seismicity and environmental pollution from oil and chemical industries. The Augusta Bay offshore displays a marked variability of morphologies and seismic–stratigraphic characters, related to the influence of both large-scale geological processes and local variables. It consists of an irregular surfaced narrow shelf, generally tracing out the shape of the relative coastline seaward bounded by a steep continental slope. This latter is deeply engraved by gullies and shows evidences of recent withdrawal, favored by the occurrence of structural lineaments. The Augusta offshore reflects the corresponding on-land geological pattern, being characterized by a central basinal area filled with Pleistocene–Holocene successions, bounded by two relieved sectors corresponding to the seaward prosecution of the Mt. Tauro and Magnisi–St. Panagia horsts, where the Miocene substratum outcrops. The seismic–stratigraphic architecture of the basinal area not only is the result of sea-level variations related to the Late Pleistocene sea-level fall and subsequent transgressive phase, responsible for the formation of a main angular unconformity, but also depends on pre-existing substratum arrangement, which leads to a wide lateral facies variability, on short distances. Morphological and seismic–stratigraphic evidences outline the presence of structural lineaments whose orientation is consistent with that of the on-land sectors. Slight movements are testified by the dislocation of recent sedimentary covers, pointing to active tectonic processes during Holocene. Such vertical movements are also responsible for a southward differential subsidence of the basinal area, whereas the proximal portion of the shelf seems to be strictly connected to the uplifting emerged sectors. This evidence is consistent with the recognition of recently active tectonic structures where the distal offshore represents the down-faulted sector. Our results, providing a detailed knowledge of the submerged sector of a highly populated area, affected by high seismicity and environmental pollution risk may significantly contribute to an appropriate management of the area in the next future. [Copyright &y& Elsevier]

The Augusta basin, located in SE Sicily (southern Italy), is a semi-enclosed marine area, labelled as a highly contaminated site. The release of mercury into the harbour seawater and its dispersion to the blue water, make the Augusta basin a potential source of anthropogenic pollution for the Mediterranean Sea. A mass balance was implemented to calculate the HgT budget in the Augusta basin. Results suggest that an average of ∼0.073 kmol of HgT is released, by diffusion, on a yearly basis, from sediments to the seawater, with a consequent output of 0.162 kmol y(-1) to coastal and offshore waters; this makes the Augusta area an important contributor of mercury to the Mediterranean Sea. Owing to the geographical location of the Augusta basin, its outflowing shelf-waters are immediately intercepted by the surface Atlantic Ionian Stream (AIS) and mixed with the main gyres of the eastern Mediterranean Sea, thus representing a risk for the large-scale marine system.