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“GeoSUB – Underwater geology” – Ustica, 13-17 September 2016

800 m of each reef have been surveyed by using high-resolution aerial orthophotomosaics
(2cm/px). Detailed 3D maps have been realized for both reefs and the following measures of
ecological relevance have been estimated: external rim length, internal rim length, surface of
external rim (mq), cuvette surface (mq) and reef surface (mq). Index of external rim development
and Index of internal rim development have been calculated as a relationship between a
standardized linear length and the length of the external and internal rim respectively.
Total area for Capo Gallo reef is 2563,26 mq; indexes of external and internal rim development
are respectively 3,40 and 1,90. For Favignana, reef area is 1263,15 mq and indexes of external and
internal rim development are respectively 2,56 and 1,80.
These results reveal RPAS as a powerful tool for physical description of vermetid reefs and to
calculate how this biogenic habitat shapes the coast and increases habitat complexity on rocky
shores. This study, moreover, shows the high potential for RPAS technique to be applied for
mapping vermetid reefs and to aid the management and conservation of natural systems, as
required by the EU Strategy on Biodiversity which declares the necessity of mapping habitats and
the ecosystem services they provide.

Fig. 1: Ortophotomosaic of Favignana’s reef and detail of the estimated measures (the blue line
corresponds to the external rim and the yellow to the internal rim).

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