PINNACARE - Conservation and restoration of Pinna nobilis

Populations of the endemic Mediterranean pearl oyster (Pinna nobilis) have been devastated by an episode of mass mortality that began in late 2016 in the western Mediterranean, primarily associated with an infection caused by the protozoan Haplosporidium pinnae. Since 2016, the disease has spread throughout all the basins of the Mediterranean Sea. Prevalence and subsequent mortality have reached almost 100% in the affected populations, leading to the ecological extinction of the species in open waters, an unprecedented process in the Mediterranean. The International Union for Conservation of Nature (IUCN) has classified the species as ‘Critically Endangered’.

Currently, the only surviving populations remain in coastal lagoons and deltas, with several thousand individuals in the Ebro Delta (Spain), the Thau Lagoon (France), the Venice Lagoon (Italy) and the Kaloni and Amvrakikos gulfs (Greece), whilst only hundreds of individuals remain in the Mar Menor (Spain), the Diana Lagoon (France) and other coastal lagoons, as well as in the Sea of Marmara (Turkey). However, these environments are also the most affected by human pressures and climate change in relation to the survival of the pearl mussel in the Mediterranean. These areas are crucial for the survival of the species, as they provide a surplus of individuals that could be used for restocking and experimental purposes.

Therefore, there is an urgent need to conserve the remaining populations, reduce the impacts of climate change and direct human activities, and compile inventories of individuals and impacts in these ‘reservoirs’. Furthermore, some areas have been identified as optimal reservoirs for the Mediterranean monk seal, but restocking is limited by a lack of local recruitment. The development of management measures for the movement of individuals between countries is also constrained by the need for an International Biosecurity Programme to ensure the safety of translocations.

Improving the reproduction and maintenance of individuals in captivity is equally necessary to ensure a source of specimens that can be used for restocking, monitoring and further experimentation on the disease and associated genetic factors.

Objectives

The main objective is to prevent the extinction of the pearl mussel in the short to medium term.

The specific objectives are:

• To improve the condition of individuals in open waters, at optimal sites and in reservoirs, including the monitoring of physico-chemical variables and other environmental conditions potentially associated with their survival.
• To establish an international biosecurity programme for the recovery of individuals in the wild, enabling the safe sharing of specimens between countries and areas.
• To use the most suitable sanctuary areas for the survival and reproduction of P. nobilis as a management model necessary for safe, long-term reintroduction into other reservoir areas.
• To improve conditions for the captive breeding of the species.
• To determine genetic diversity and the genetic factors associated with immunity to the disease.
• Develop a treatment to alleviate the effects of the disease in the laboratory, cure juveniles and improve captive breeding using sick individuals.
• Raise global awareness to reduce the risk of vandalism and illegal harvesting of the remaining pearl mussels, and promote broad public engagement.
• Conduct a socio-economic study of the project’s impact.

The project focuses primarily on the reserves and on maintaining individuals for breeding in facilities (‘indoor’ breeding), as open-water populations have disappeared. In open waters, it is important to continue protecting and monitoring any resilient and hybrid individuals found, to safeguard their diversity for future cross-breeding. If no action is taken, the few resilient individuals detected to date will eventually die without leaving offspring, and the populations in the reservoirs will decline, with no capacity to repopulate if natural or anthropogenic factors, or the disease itself, affect them.

Disclaimer: Co-funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or CINEA. Neither the European Union nor the granting authority can be held responsible for them.