Shallow rhodolith beds in Capo Peloro lagoon

Rhodoliths, as unattached benthic rhodophycean algae precipitating CaCO3, are relevant component of marine coastal environments, where they play a significant role as habitat forming organisms. Rhodolith beds are most common in the Circalittoral zone, because favored by low light intensity and scarce competition with green and brown algae. Shallow water rhodolith beds are little investigated, even less in brackish environments. In the Capo Peloro Lagoon (north-eastern Sicily), rhodolith beds widely occur both in Lake Faro and canals connecting the system to the sea. In the canals, in fact, tidal currents hamper mud sedimentation and improve water exchange. Moreover, the currents that flow back from the lake supply nutrients and reduce light intensity. In Lake Faro, where turbidity is a prevalent condition, mud sedimentation is mainly hampered by the anthropogenic disturbance caused by traditional practices of clam farming. The same practices, in both environments, mostly provide deposits of bioclasts constituting the rhodolith accretion core. In the framework of the investigation aimed to evaluate and monitor the benthic biodiversity of Capo Peloro Lagoon (PO FEAMP SICILIA 2014-2020, Mis. 2.51), a preliminary assessment of the main lake-floor typology and associated communities has been carried out. A systematic underwater visual survey was conducted, and rhodolith beds were georeferenced. Samples randomly collected by each bed provided a first rhodolith characterization and a morphological based identification of species. From the same samples, fragments were isolated, dried in silica gel, and analyzed by DNA barcoding method. In this regard, the use of DNA barcodes, giving a permanent labelling, independent from possible future taxonomic and nomenclature changes, confirmed to be essential in the contest of the environment protection management. Neogoniolithon brassica-florida (Harvey) Setchell & L.R. Mason, Neogoniolithon hauckii (Rothpletz) R.A. Townsend & Huisman and Phymatolithon lenormandii (Areschoug) W.H. Adey, as most common coralline morphospecies, revealed to be major actors in the lake-floor stabilization and habitat structuration, further than underline close relationships with long-time persistent human activities.