The fan mussel (Pinna nobilis*) is the largest endemic bivalve of the Mediterranean Sea. It occurs in soft-bottom habitats of transitional water ecosystems and in marine coastal zones at depths between 0.5 and 60 m, mostly in seagrass meadows of Posidonia oceanica or Cymodocea nodosa, but also in bare, sandy bottoms. This species is an important benthic filter feeder contributing to water clarity, and a “conservation species”, playing the roles of flagship, key and umbrella species. Due to its ecological relevance, P. nobilis has been suggested as being a reliable bioindicator for benthic coastal ecosystems according to Descriptor 1 “Biological diversity” and 4 “Status of the single structural components of ecosystems” of the EU Marine Strategy Framework Directive. In addition, the fan mussel represents the host for two crustacean symbionts (Pontonia pinnophylax and Nepinnotheres pinnotheres) and it is also predated by other species, such as Octopus vulgaris, playing a key role in the trophic web. During the 1980s, populations of P. nobilis declined greatly due to human activities (fishing, ornamental harvesting, anchoring and trawl nets). As a consequence, P. nobilis is nowadays a species subject to strict protection, listed in Annex IV of the EU Habitats Directive as prioritary and in the Annex II List of endangered or threatened species of the SPA/BD Protocol of the Barcelona Convention. It is also included in the IUCN Red List as critically endangered.
In a few decades, this full regime of protection led to a complete recovery of the species in the whole Mediterranean, as was evidenced by molecular analyses. Unfortunately, since early autumn 2016, a mass mortality event impacted P. nobilis populations in the south-western Mediterranean Sea. The situation worsened, gradually affecting the Spanish, French, Tunisian, perhaps Turkish and, inevitably, Italian coasts, where fan mussels have been dying. The protozoan Haplosporidium pinnae, a pathogenic microorganism that affects the digestive system of the mollusc, progressively reducing the animal’s feeding and causing its death, was initially imputed as the main cause of this mass mortality. However, recently several bacteria species have also been invoked as pathogens involved in the mass mortality of fan mussels, suggesting that the real causes are not completely understood and that a multifactorial disease may be the most probable responsible factor.
Given such mass mortality events which have affected the Mediterranean populations in recent years (never reported for any other pinnids worldwide), this project targets the protection and conservation of P. nobilis, in order to avoid its extinction. In the regions involved in this project, the situation of P. nobilis survivors is different; they are likely characterised by a natural resistance to the pathogens responsible for the disease outbreak, but analysis of the level of pathogenic infection in the tissues of these individuals may be useful to identify the relevant microorganisms. It is also important to assess the level of contamination/infection occurring where the fan mussels died and where they survived.
The LIFE PINNA project’s objective is to conserve fan mussels in the Western Mediterranean and the Adriatic Sea. It aims to achieve this by applying specific conservation and repopulation actions in pilot areas, that are transferable to other regions.
The specific objectives include:
- Analysis and selection of marine or transitional areas appropriate for restocking;
- Molecular characterisation of surviving specimens and selection of the best candidates to be reproduced;
- Development and implementation of the most suitable repopulation techniques, through translocation of self-recruited juveniles and captive breeding of P. nobilis in order to release a large number of specimens into the wild in a few years;
- Maintenance of a good level of genetic variation among the individuals used for restocking in order to obtain offspring that will be the founders of new future populations with good fitness in the long term;
- Monitoring of donor sites to evaluate the status of P. nobilis (including citizen science actions);
- Monitoring of “sentinel” organisms for the infection level of pathogens responsible for mass mortality of P. nobilis, to quickly detect anomalous values that are potentially dangerous for the species’ survival;
- Public engagement to increase awareness on P. nobilis and influence sea users’ behaviour; and
- Transfer and replication of skills and methodologies to areas where the fan mussel is decreasing.
The project will contribute to implementation of the EU’s Habitats and Marine Strategy Framework directives, as well as the Barcelona Convention and EU and national biodiversity strategies.
- Selection and characterisation of at least 6 marine protection areas (Capo Mortola and Bergeggi in Liguria, Isola dell'Asinara in Sardinia, Miramare in Friuli-Venezia Giulia, Strunjan Park in Slovenia, and the Tuscan Archipelago) appropriate for restocking, and molecular characterisation of the best candidates to be reproduced;
- Georeferenced map of the best pilot sites for the restocking actions and map of the presence of specimens in all involved regions;
- Installation of at least 3 restocking plants;
- 200 individuals released through restocking actions;
- Maintenance of a good level of genetic variation among the individuals used for restocking;
- Creation of a genetic database;
- Protocols for replicability, validated by the national or regional authorities, on: selection of restocking sites; best restocking techniques (methods of juvenile capture, controlled growth, transport, installation of specimens); best practices for controlled reproduction in captivity; agreement scheme for juvenile capture; and identification form for tracking the transport of specimens (from protected areas with the presence of survivors to areas with high P. nobilis mortality);
- Training of 15 persons in charge of restocking conservation action;
- Involvement of at least 100 citizens through community science activities;
- Environmental education actions reaching at least 500 young people;
- 850,000 people reached also through a web-marketing strategy to selected publics sensible to marine issues;
- Report on the cost-efficient replicability and transferability of the project’s solutions in 2 other sites: Bergeggi marine protected area (MPA) and the Tuscan archipelago; and
- Protocols on various aspects of protecting P. nobilis, diffused among MPA authorities, obtaining 50 expressions of interest to apply them.