The largest bivalve in the Mediterranean Sea
1st October 2021 marked the beginning of the project LIFE20 NAT/IT/001122 PINNA “Conservation and re-stocking of the Pinna nobilis in the western Mediterranean and Adriatic sea”, 60% co-financed through the European Union financial instrument LIFE program. This project brings together several partners: Triton Research, as responsible for communication and project management, ARPAL Liguria Regional Agency for the Environmental Protection as coordinating beneficiary; Asinara National Park, National Institute of Biology, Shoreline Cooperative society, University of Genova and University of Sassari as beneficiaries. Therefore, four Italian regions are geographically concerned by the development of this four-year project which will officially end on 30 September 2025: Liguria, Sardinia, Friuli-Venezia Giulia and Tuscany, in addition to the cross-border region of Obalno-kraska, in Slovenia.
Commonly known as common fin, castanet, or pen mussel, the Pinna nobilis is today the largest bivalve mollusc endemic in the Mediterranean sea which can exceed 100 cm in height and reach 45 years. Its presence is often linked to the Posidonia oceanica meadows representing real ecosystems to support the biodiversity of the Mediterranean and protected by the Habitat Directive for its importance and at the same time fragility.
Several threats have in the past decimated the species on a local scale. Among them are life habitats, coastal habitats occupied – shallow and easy to reach – and anchoring structures to the seabed structure, which have contributed to the Pinna nobilis is one of the most threatened species in our seas. In addition, shell collectors and byssus collectors, a precious set of filaments produced by Pinna specimens to anchor to small rocks and submerged plans that are used by humans as raw materials to produce textile fibers.
Today, unfortunately, the species is still suffering from a serious demographic decline, due to different anthropogenic factors, such as the aforementioned illegal harvesting for ornamental purposes, recreation and commercial fishing, coastal infrastructure, the use of anchors, pollution and trawl fishing. A negative role may be played also by climate change to which the increase in water temperature is linked. This effect is harmful to the development of younger specimens. Another worrying event is the mass mortality that began in 2016 and is linked to the spread of a protozoan, Haplosporidium pinnae, which is able to reduce the assimilative capacity of nutrients in all specimens attacked by the diseases, leading them to early death and an increased risk of predation – due to the valves not closing properly.
Further investigations revealed also a widespread and multispecies bacterial infection is affecting specimens of Pinna nobilis, making its conservation status even more dramatic and its future even more uncertain. Due to the number of threats, the mollusc is now classified as Critically Endangered under the IUCN Red List.
In the event of extinction in the wild, the loss in terms of biodiversity and ecosystem services would be severe. This filter-feeder which contributes to the transparency of water and filtering and retaining a large amount of organic matter otherwise in suspensions, plays a key role in the trophic network as prey for numerous marine species, from the gastropod Hexaplex trunculus to the fish Sparus aurata, and the better-known octopus Octopus vulgaris. As well as being a provider of ecosystems services, such as water filtering and food resource, Pinna nobilis hosts other marine organisms, in particular crustaceans, contributing to the specific and genetic biodiversity of our seas. Moreover, Pinna nobilis has an undisputed ecological and conservation value, covering the role of flag species, key and umbrella species of the Mediterranean.
Triton’s hope is that through joint efforts of all the partners involved in the LIFE PINNA project, the process of extinction of this species on a Mediterranean scale can be stopped. Several actions are being taken, all equally important:
- Selection of proper restocking sites for the survival and reproduction of Pinna nobilis, using sentinel species of molluscs (Mytilus galloprovincialis spp.) as bio-indicator of the presence of etiological elements in coastal environments.
- Collection of information on environmental and ecological characteristics that can support a viable population of Pinna nobilis.
- Definition of best practices for the collection of live specimens, transport, growth monitoring and reintegration into the wild.
- Constant comparison and exchange of know-how with other European projects regarding the best practices for the transport and handling of Pinna nobilis specimens.
- Collection of young specimens to be used for captive breeding.
- Reproduction and captive breeding of Pinna nobilis specimens to be used for reintegration into nature.
In particular, the latter action is the most challenging for the whole team, as it is a pioneering action that has never been tested on Pinna nobilis, even though it is based on protocols and projects carried out for other species. This is a major technical and scientific responsibility that we are taking on together with our project partners so that we can once again admire these large bivalves in the Mediterranean sea waters.
Triton is in charge of the communication activities, with the primary aim of developing and implementing a communication plan that can make the main project objectives known to the widest possible audience of marine users. These includes:
- Transfer knowledge about the delicate biology of the Pinna nobilis species and threats to its conservation.
- Lead users of the marine ecosystem to adopt correct behaviors to guarantee the protection and conservation of Pinna nobilis for future generations.
- Involve people with a strong green attitude and sensibility, transforming them into ambassadors for the protection of the species.
- Involve economic operators linked to coastal environments in the dissemination of positive messages aimed at protecting the sea and its biodiversity.
- Promote Life programme and Natura2000 network as instruments for the implementation of EU biodiversity conservation policy.
- Amplify the impact in other geographic areas, with other entities involved in the protection of marine biodiversity and other species through the transfer and replication of good practices and efficient methodologies used in the project.
- Encourage networking activities with other LIFE and other projects throughout the duration of LIFE PINNA, providing opportunities for discussion, exchange of experience and sharing technical and scientific documents through dedicated events.