Characterization of rhodolith beds-related backscatter facies from the western Pontine Archipelago (Mediterranean Sea). (July 2021)

• Record Type: Journal Article
• Authors: Sañé, E.; Ingrassia, M.; Chiocci, F.L.; Argenti, L.; Martorelli, E.
• Is Part Of: Marine environmental research. Volume 169(2021)
• Publication Date: 2021-07
• Subjects: Rhodolith beds -- Backscatter facies -- Statistical analysis -- Sediment grain size -- ROV videos; Marine pollution -- Environmental aspects -- Periodicals; Marine ecology -- Periodicals; Mer -- Pollution -- Aspect de l'environnement -- Périodiques; Écologie marine -- Périodiques; Electronic journals; 577.705
• DOI: 10.1016/j.marenvres.2021.105339
• Languages: English
• ISSNs: 0141-1136

Abstract

Abstract: Rhodoliths (nodular calcareous red algae) are considered one of the most important bioengineers in the Mediterranean Sea, making rhodolith beds ecologically relevant ecosystems. On the insular shelf surrounding the western Pontine Archipelago (depth from 43 to 112 m), rhodolith beds were identified through the analysis of an extensive dataset of grab samples and videos to ground-truth the backscatter acoustic facies. Six acoustic facies (low backscatter, dishomogeneous low-backscatter, dishomogeneous high-backscatter, high-backscatter, rocks and high backscatter, and rocks and medium backscatter) were recognized. We studied how rhodoliths characteristics (density, morphotype, size and structure) differently influence the backscatter signature. At the western Pontine Archipelago, rhodolith beds are mainly represented by facies dishomogeneous high backscatter, high backscatter, high backscatter with rocks, and medium backscatter with rocks. The obtained results increase both the knowledge on the heterogeneous structure of such ecologically relevant benthic habitat and highlight the use of distinctive acoustic facies for their identification. Finally, the used approach could be considered a useful method for indirect detection and mapping of rhodolith beds. Highlights: Rhodoliths are associated to particular backscatter facies. Pralines and unattached branches are associated to high backscatter facies. Rhodoliths are scarse in low backscatter facies. Coarse sediments are associated to high backscatter facies. Side scan sonar facies are useful to map rhodolith beds.