Population trends of the fan mussel Pinna nobilis from Portofino MPA (Ligurian Sea, Western Mediterranean Sea) before and after a mass mortality event and a catastrophic storm

Two Pinna nobilis populations thriving inside the borders of the Portofino Marine Protected Area (MPA) (Ligurian Sea, western Mediterranean Sea) were monitored before (2012) and after (September 2018) a dire mass mortality event that, since September 2016, spread through the whole Mediterranean Sea. In Portofino MPA, recorded mortality rates reached values of 91.29% and 43.94% in the two populations. The presence of a Haplosporidium protozoan parasite, considered to be the main cause of the mortality episodes, was confirmed from histological evidence: sporocysts and plasmodia were observed in all the tubules of the digestive glands of the collected specimens. Moreover, a catastrophic storm hit the Ligurian coasts at the end of October 2018, causing considerable damages both below and above the surface; a new survey conducted in November 2018 showed the complete annihilation of the two studied populations, as a probable combination of the continued parasite infections and the mechanical impacts caused by the storm. Finally, in June 2020 the sites were monitored again looking for traces of recovery, but no new specimens were recorded, indicating that P. nobilis became virtually absent from the MPA

Population trends of the fan mussel Pinna nobilis from Portofino MPA (Ligurian Sea, Western Mediterranean Sea) before and after a mass mortality event and a catastrophic storm

Two Pinna nobilis populations thriving inside the borders of the Portofino Marine Protected Area (MPA) (Ligurian Sea, western Mediterranean Sea) were monitored before (2012) and after (September 2018) a dire mass mortality event that, since September 2016, spread through the whole Mediterranean Sea. In Portofino MPA, recorded mortality rates reached values of 91.29% and 43.94% in the two populations. The presence of a Haplosporidium protozoan parasite, considered to be the main cause of the mortality episodes, was confirmed from histological evidence: sporocysts and plasmodia were observed in all the tubules of the digestive glands of the collected specimens. Moreover, a catastrophic storm hit the Ligurian coasts at the end of October 2018, causing considerable damages both below and above the surface; a new survey conducted in November 2018 showed the complete annihilation of the two studied populations, as a probable combination of the continued parasite infections and the mechanical impacts caused by the storm. Finally, in June 2020 the sites were monitored again looking for traces of recovery, but no new specimens were recorded, indicating that P. nobilis became virtually absent from the MPA

Optimization of scuba diving activities in a Mediterranean marine protected area based on benthic vulnerability assessment

Scuba diving has become an increasingly popular recreational activity, involving approximately 6 million active divers worldwide.The high frequency of diving can impact the benthic communities of marine protected areas (MPAs), possibly jeopardizing the beneficial effects of protection.The Portofino MPA, in the Ligurian Sea, is one of the main scuba diving destinations in Europe, with up to 40,000 dives per year concentrated along 6.5 km of coast.The vulnerability of megabenthic (i.e. animals larger than 5 cm) communities to scuba diving impacts was evaluated at four different depths at all MPA diving spots with close attention to the fragility of all observed species, their frequency in the transects and the inclination and type of substrates.The most vulnerable spots lie below 30-m depth and are characterized by complex coralligenous biocoenoses rich in erect, fragile carbonatic species.The results allowed scuba diving management within the MPA to be optimized. Two main responses have already been put in place: (i) the promotion of a mandatory course for 'Underwater Environmental Supervisors' directed at local divemasters, instructors and owners of diving centres; and (ii) the proposal for the application of conservation measures to scuba diving activities

Scuba diving impact on the red coral population of the Portofino MPA

Thanks to the analysis of detached red coral (Corallium rubrum, Linnaeus, 1758) colonies found within the coarse sediments present at the base of the MPA Portofino cliffs, the impact of the scuba diving activities has been evaluated and discussed