Biodiversity associated with Sabellaria (Polychaeta: Sabellariidae) bioconstructions: new data from central Mediterranean Sea.

Abstract

In the Mediterranean Sea, the polychaete genus Sabellaria Lamarck, 1818 is represented by two species: Sabellaria alveolata (Linnaeus, 1767) and S. spinulosa (Leuckart, 1849). These species are known to build reefs using sand and shell fragments for the construction of tubes in which the worms live. Sabellaria’s bioconstructions can be naturally ephemeral since they are strictly dependent on hydrodynamics energy and sand and nutrient supply. Even if subject to periodic reduction or dismantling due to hydrodynamics, these bioconstructions can persist over time. The two species show much more extensive reefs along Northern Atlantic coasts than on the Mediterranean Sea. Sabellaria reefs are important because they offer protection and shelter from predators to different organisms, including some intertidal species that remain periodically exposed to dessiccation, and because they represent nursery areas for several organisms. We provide new distributional and biological data on the occurrence of both species S. alveolata and S. spinulosa from Italian coasts (Abruzzo, Latium and Sicily) and the associated fauna was studied taking into account different detected taxonomic groups. The most represented taxa are Polychaeta and Crustacea, that include amphipods, isopods and decapods. These two groups are represented by numerous species although with relevant differences on the quali-quantitative composition depending on the geographical area. The most abundant species are the polychaetes Eulalia ornata Saint-Joseph, 1888, Hydroides dianthus (Verrill, 1873), Hydroides elegans (Haswell, 1883), Nereis splendida Grube, 1840 and Spirobranchus triqueter (Linnaeus, 1758); and the amphipods Apocorophium acutum (Chevreux, 1908), Microdeutopus algicola Della Valle, 1893 and Plumulojassa ocia (Spence Bate, 1862). In conclusion we underline the importance of the ecological role of Sabellaria reefs in ensuring a peculiar substratum and pabulum to species rarely detected in the Mediterranean Sea.