The largest bivalve in the Mediterranean Sea, the fan mussel Pinna nobilis, is at risk of extinction due to mass mortality events (MMEs) caused by the spread of pathogens, Haplosporidium pinnae in particularly. In spite of being a protected area, Lake Faro (northeast Sicily, Italy) suffers from high anthropogenic pressures that affect the P. nobilis population that inhabits the lake and the two canals that connect it to the sea. In the present study, the population’s long-term changes have been monitored in three distinct periods: before the MME (2010), at the beginning of the epidemic spread along the Italian coasts (2018), and after the MME (2020). The survey, carried out by visual census, showed that, relative to 2010, the population of P. nobilis halved in 2018 and disappeared from the canals in 2020; while in the lake, living specimens were only 27.69 % of the total at this time, without recruits. The disappearance of P. nobilis, allowed rapid colonization by the congeneric Pinna rudis and the invasive oyster Pinctada imbricata radiata, which had never been recorded in the Lake Faro system before 2020.

This research was sponsored by the ‘Città Metropolitana di Messina’ the official management body of the reserve (permission no. 557/VIII DIR, March 12, 2014). Facilities were provided by the mussel farm FARAU s.r.l. This research has been partially supported by LIFE IP INTEMARES project, coordinated by the Biodiversity Foundation of the Ministry for the Ecological Transition and the Demographic Challenge (European Union's LIFE programme; LIFE15 IPE ES 012). MVL was supported by a postdoctoral contract Juan de la Cierva-Incorporación (IJCI-2016-29329) of Ministerio de Ciencia, Innovación y Universidades.

Peer reviewed