Sea Floor of the Marine Protected Area of the Asinara Island (Sardinia, Italy)

Figures & data

Figure 1. Sardinia Island. (A) Satellite view of the Mediterranean region where Sardinia occupies a central position. Dashed line indicates the Sardinia anticlockwise rotation occurred in the Neogene time. A read * is point at the Asinara Island (source of the picture is Google Earth); (B) Digital terrain model of Sardinia; in the map are reported the main cities. In the square, the Asinara Island studied area. Abbrevitions: BI = Balearic Islands; lp = Liguro-Provençal Basin; Ty = Tyrrhenian Sea. C) The Asinara Isla (nd). In the picture are indicated the limit and zones, with different degrees of environmental protection of the Marine Protected Area: (red line) no-entry no-take (Zones A); (yellow line) general reserve (Zone B), and (withe line) partial reserve (Zone C) (source of the picture is Ortophoto 2008-Regione Sardegna, RAS).

In the main picture, C is the Asinara Island, located in the northwestern end of Sardinia Main Island occupying a central position in the Mediterranean Sea. The Asinara Island being ‘an island in an island’ was a high security prison until 1997. This has allowed the maintenance of peculiar Mediterranean flora and fauna and prevented serious damage to the coastal marine assemblages making it one of the most uncontaminated marine ecosystem of the Mediterranean Sea.

Figure 2. (A) Side Scan Sonar (SSS) sea floor mosaic of the Asinara Island (modified after Romeo et al., 2019). Dashed lines indicate the 21 ROV transects, red and black spots the extrapolated transects; (B) Detail of the SSS mosaic relative to the western side of the island. Note that lower backscatter (Lb) dominates the narrow areas in front of the gravelly pocket beaches, whereas the higher backscatter (Hb) dominates the deepest part of the shelf. Pr = pre-Coralligenous, Cr = Coralligenous; (C) Detail of the SSS mosaic of the Cala della Reale embayment. Note the quasi-circular clearing (Cl) interrupting the continuity of the Posidonia oceanica meadow (patchy backscatter = Pb); I = channels, s = spot of Biocenosis at Holothuria sp. Codium bursa Feoficee. (D) Detail of the SSS mosaic in front of P.ta Sabina. Pb = P.oceanica patchy backscatter, Lb = fine sand lower backscatter, Ab = alternate high and low backscatter relative to the dune field (D). The dune field is NNE-SSW oriented.

The Side Scan Sonar mosaic realized after the integrated processing of 100 and 500 KHz frequency. The final mosaic has a resolution of 0.2 pixel/m.

Figure 3. High Resolution swath bathymetric map (Multi Beam) of the Marine Protected Area of the Asinara Island. Arrows indicate the channels of the Cala della Reale emabyment; cl = quasi-circular, funnel shaped clearing, br = beachrocks, D = Dune field (Modified after Romeo et al., 2019).

High-resolution swath bathymetric map of the Asinara Marine Protected Area. The digital terrain model of the Asinara Island has been taken from http://www.sardegnageoportale.it.

Figure 4. Biocenosis of the upper infralittoral rock in sheltered waters. (A) Lithophyllum byssoides (Lamarck) Foslie and (B) Patella ferruginea (Gmelin).

The high wave dominated cliffs of the western side of the Asinara Island favor the development of Lithophyllum byssoides (Lamarck) Foslie. These from reef-like bioconstructions known as trottoirs (Sechi et al., 2018, 2020). Where the substrate is made of silica rich rocks (i.e granites) Patella ferruginea (Gmelin) may develop. This species is endemic to the western Mediterranean and considered one of the most threatened invertebrates in this geographical region.

Figure 5. Coralligenous reefs. In the pictures are visible the following species: Lithophyllum sp., Mesophillum sp. Peyssonnelia rubra (Gmelin), Flabelia petiolata (Turra) Nizamuddin, Peyssonnelia squamaria (S. G. Gmelin) Decaisne, Osmundaria volubilis (L.) R.E. Norris and colonies of Eunicella cavolinii. The two red dots distance is 10 cm.

ROV survey conducted around the western side of the Asinara Island has allowed imaging well-preserved Coralligenous reefs. These are biocenotic complex habitats generating tridimensional biogenic structures, mainly produced by the accumulation of calcareous encrusting algae growing in reduced light conditions.

Figure 6. The Laminaria rodriguezii Bornet.

This picture of the Laminaria rodriguezii Bornet has been acquired during ROV survey of the western side of the Asinara Island. This deep-water brown alga, endemic of the Mediterranean Sea, is normally found fixed to big rocks. This laminaria is safeguarded in the Mediterranean Sea.

Romeo, R., Baradello, L., Blanos, R., Congiatu, P. P., Cotterle, D., Ciriaco, S., Donda, F., Deponte, M., Gazale, V., Gordini, E., Lodolo, E., Paganini, P., Pavan, A., Pietrapertosa, C., Sterzai, P., Vargiu, G., Zanello, A., Ramella, R., & Nieto Yabar, D. G. (2019). Shallow geophysics of the Asinara Island Marine Reserve area (NW Sardinia, Italy). Journal of Maps, 15(2), 759–772. https://doi.org/10.1080/17445647.2019.1669498

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Data availability statement (DAS)

All the data used to realize the Sea Floor Map of the Asinara Island are property of the National Park of the Asinara Island. They could be requested directly to the park writing at [email protected], or visiting the website http://www.parcoasinara.org/