Biodiversity loss in Sicilian transitional waters: the molluscs of Faro Lake

Sediment samplings were carried out in six stations of Faro Lake (Sicily, Italy) during spring and autumn 1991, and spring 1993, 2006, 2010, to investigate the soft bottom mollusc assemblages. The study have provided the first quantitative data on the mollusc fauna of Faro Lake, to date known only for some dated inventories. Some differences in species composition in respect to the ancient literature were highlighted. The 1991-2010 data sets showed changes in the mollusc assemblages, which impoverished in composition and structure. Basic indices of community structure (S, d, H’, J’) indicate a marked decline in the 2006, followed by a recovery period during 2010. The multivariate analysis, based on a the Bray-Curtis similarity index, proved that mollusc assemblages sampled prior to the 2006 crisis were more structured and spatially differentiated than those settled later. The observed decline of endemic taxa and the concurrent settlement of species introduced by mussel farming, make the mollusc assemblages in the Faro Lake a case-study for the effect of species introduction in confined environments.