PROJECT DESCRIPTION
BACKGROUND
The Fan mussel (Pinna nobilis) is the largest endemic bivalve in the Mediterranean Sea. This invertebrate occurs in soft-bottom habitats of transitional water ecosystems and in marine coastal areas at depths of between 0.5 and 60 metres, mostly in seagrass meadows of Posidonia oceanica or Cymodocea nodosa, but also in bare, sandy bottoms.
This species is an important benthic filter feeder improving water quality and plays 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 the EU Marine Strategy Framework Directive (Descriptors 1 “Biological diversity” and 4 “Status of the single structural components of ecosystems”).
In addition, the Fan mussel is the host for 2 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 today a species subject to strict protection, listed in Annex IV of the EU Habitats Directive as priority 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 across the whole Mediterranean. However, after a mass mortality event taking place since 2016 in the south-western Mediterranean Sea, the situation worsened, gradually affecting the Spanish, French, Tunisian, Turkish and, inevitably, Italian coasts. The protozoan Haplosporidium pinnae, a pathogenic microorganism that affects the digestive system of the mollusc, was initially imputed as the main cause. However, several bacteria species had also been invoked as pathogens involved in the mass mortality of Fan mussels, suggesting that a multifactorial disease may be the most probable responsible factor.
In the regions involved in this project, the P. nobilis survivors were considered to be likely characterised by a natural resistance to the pathogens responsible for the disease outbreak.
OBJECTIVES
The main objective of LIFE PINNA project was to conserve Fan mussel in the Western Mediterranean and the Adriatic Sea. It aimed to achieve this by applying specific conservation and repopulation actions in pilot areas, transferable to other regions.
The specific objectives included:
- Analysis and selection of marine or transitional conservation 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
- Maintenance of a good level of genetic variation among the individuals used for restocking in order to obtain offspring as 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), with the involvement of at least 100 citizens through community science activities
- 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 environmental awareness on P. nobilis and influence sea users’ behaviour, targeting 850 000 people reached also through a web-marketing strategy directed at selected audiences sensitive to marine ecosystem issues
- Transfer and replication of skills and methodologies to areas where the fan mussel was decreasing.
The project aimed to contribute to the implementation of the EU Habitats and Marine Strategy Framework Directives, as well as the Barcelona Convention, the EU Biodiversity Strategy 20230, and the Italian national biodiversity strategy.
RESULTS
The project did not achieve its main conservation objective or all its expected results. This was mainly due to natural reasons, specifically due to the disease affecting the species throughout its distribution range, with the critical situation of the species further worsening during the project.
Despite this fact, and thanks to the implementation of contingency measures and activities, the following results were achieved:
- 4 pilot areas, out of the 6 foreseen, characterised and assessed suitable for the species (Capo Mortola, Miramare, Strunjan, Asinara); georeferenced maps of restocking sites and specimen presence produced for all involved regions; Asinara area was excluded from active restocking due to insufficient availability of individuals
- Molecular characterisation of surviving individuals completed
- Genetic database created, incorporating mitochondrial (COI gene) sequences from all known surviving populations, integrated with historical samples spanning up to 300 years (data acquisition); microsatellite data generated for northern Adriatic populations
- Good level of genetic diversity confirmed in northern Adriatic donor populations; surviving individuals carry ancient Mediterranean lineages, validating their suitability as restocking founders
- 3 restocking plants operational throughout the project as foreseen: Università di Genova laboratory in Camogli (captive breeding of adults from the Venice Lagoon), Shoreline facilities in the Gulf of Trieste/Miramare MPA (lantern-nets and aquaria for juveniles from larval collectors), and National Institute of Biology facilities in Piran, Slovenia (aquaria and lantern-nets for juveniles along the Slovenian coast)
- 94 individuals, out of the foreseen 200, were translocated (mainly from the Venice Lagoon) to 4 MPAs (Capo Mortola, Miramare, Strunjan and Bergeggi); all specimens survived for several months post-translocation but were subsequently found dead during monitoring
- 5 replicability protocols developed, covering: site selection; juvenile capture and growth; specimen transport and tracking; captive reproduction; and reintroduction techniques. Protocols were adopted at Mediterranean level through a Decision of the Barcelona Convention Contracting Parties (RAC/SPA, 2024)
- Extensive environmental training and capacity-building activities delivered: regional training in Tunisia; international webinar on restocking of P. nobilis; training course on marine restoration
- Citizen science network active throughout the project; divers contributed to identification of individuals in high-risk areas; dedicated Report Pinna portal active on project website
- 231 students reached through educational activities (90 school-age pupils and 141 university students, through theoretical lessons, laboratory visits, and snorkelling activities)
- 5 000 people directly involved in over 30 dissemination and citizen science events (scientific festivals, public talks, marine station open days, photo contests); 721 people with improved capacity or knowledge (381 researchers and 340 students/citizens); 13 000 unique website visitors; social media coverage exceeding 1.6 million through 4 years of sponsored campaigns; total media audience estimated at over 10 million people through approximately 400 citations (TV, press, online)
- Report on cost-efficient replicability produced
- Collaboration agreements were formalised with Bergeggi MPA and Tuscan Archipelago National Park (where monitoring activities for P. nobilis were implemented).
Overall, the project outcomes and findings from analytic and monitoring tasks improved the knowledge on the Fan mussel and its ecological requirements, which may benefit future conservation actions according to the activities foreseen in the After-LIFE Plan.
