Muschelseide – Goldene Gewänder aus dem Meer

Zu den tierischen Rohstoffen, die der Mensch vor Erfindung der synthetischen Fasern nutzte, gehört eine besonders feine und seltene Faser zur Herstellung von Kleidungsstücken, die Byssus- oder Muschelseide. Hierbei handelt es sich um die Haftfäden der Edlen Steckmuschel Pinna nobilis Linnaeus, 1758 aus dem Mittelmeer, die bei erwachsenen Exemplaren bis 20 cm lang werden können. Schon in der Antike wurden aus diesen Fasern kostbare goldglänzende Gewänder in feinster mühevoller Handarbeit gefertigt. Nach einer Blütezeit während des Römischen Reichs wurde sie in den folgenden Jahrhunderten bis in das 20. Jh. zu Kleingegenständen, wie Handschuhe, Strümpfe oder Stickereien, verarbeitet. Die Zentren der Muschelseidenverarbeitung lagen im Golf von Tarent und auf Sardinien. Aufgrund von Überfischung kamen die Bestände fast zum Erlöschen und 1992 wurde die Art unter Schutz gestellt. Heute wird die Verarbeitung der Muschelseide nur noch zur Bewahrung eines alten Kunsthandwerks betrieben. In der Zoologischen Sammlung Rostock werden zwei Paar Handschuhe aus Muschelseide aus der 2. Hälfte des 18. Jh. aufbewahrt. Shell silk – golden robes from the sea Abstract: A particularly fine and rare fiber belongs to the animal raw materials that man used to make clothes, before the invention of synthetic fibers. It is byssus- or shell silk. This is the adhesive threads of the noble pen shell Pinna nobilis Linnaeus, 1758 from the Mediterranean Sea, which can grow up to 20 cm long in adult specimens. Even in ancient times, these fibers were used to make precious shiny gold garments with the finest of painstaking craftsmanship. After a heyday during the Roman Empire, it was processed in the following centuries until the 20th century to small items such as gloves, stockings or embroidery. The centers of shell silk processing were in the Gulf of Taranto and in Sardinia. Due to overfishing, the stocks almost became extinct and were placed under protection in 1992. Today, the processing of mussel silk is only carried out to preserve an old craft. Two pairs of gloves made of mussel silk from the 2nd half of the 18th century are kept in the Rostock Zoological Collection.

Pathophysiological Responses of Pinna nobilis Individuals Enlightens the Etiology of Mass Mortality Situation in the Mediterranean Populations

Due to the rapid decrease of Pinna nobilis populations during the previous decades, this bivalve species, endemic in the Mediterranean Sea, is characterized as ‘critically endangered’. In addition to human pressures, various pathogen infections have resulted in extended reduction, even population extinction. While Haplosporidium pinnae is characterized as one of the major causative agents, mass mortalities have also been attributed to Mycobacterium sp. and Vibrio spp. Due to limited knowledge concerning the physiological response of infected P. nobilis specimens against various pathogens, this study’s aim was to investigate to pathophysiological response of P. nobilis individuals, originating from mortality events in the Thermaikos Gulf and Lesvos and Limnos islands (Greece), and their correlation to different potential pathogens detected in the diseased animals. In isolated tissues, several cellular stress indicators of the heat shock and immune response, apoptosis and autophagy, were examined. Despite the complexity and limitations in the study of P. nobilis mortality events, the present investigation demonstrates the cumulative negative effect of co-infection additionally with H. pinnae in comparison to the non-presence of haplosporidian parasite. In addition, impacts of global climate change affecting physiological performance and immune responses result in more vulnerable populations in infectious diseases, a phenomenon which may intensify in the future.

The last fortress fell: mass mortality of Pinna nobilis in the Sea of Marmara

A spring 2021 cruise to the south Marmara Islands revealed a mass mortality event of Pinna nobilis, which were reported to be healthy just seven months ago. The cause of death might be associated with the epidemic infection or a catastrophic mucilage event seen after November 2020 in the Sea of Marmara. A total of 191 Pinna nobilis individuals were found at seven stations out of 10, of which 88% were dead. In the present study, the population density (dead and alive individuals) of P. nobilis was found to be between 0.3 ind.100 m-2 and 12 ind.100 m-2 in the area. A total of three live and four dead juvenile individuals were observed in the area, indicating low recent recruitment. The highest number of dead Pinna nobilis individuals (92 specimens) was encountered in shallow-waters (0-4 m depth). A total of 34 species belonging to six taxonomic groups (Sipuncula, Oligochaeta, Polychaeta, Crustacea, Mollusca, and Pisces) were found within the dead shells of four P. nobilis individuals. The mass mortality of Pinna nobilis in the Sea of Marmara, the last remaining disease-free sea, indicates the necessity of establishing and implementing emergency action plans for this species, including ex-situ conservation.

Is the local extinction of Pinna nobilis facilitating Pinna rudis recruitment?

Until the late 2010s the spiny fan-mussel Pinna rudis shared habitat in many Mediterranean sites with Mediterranean endemic Pinna nobilis, which dominated in abundance but that has gone locally extinct in most of its distribution area due to a recent widespread disease outbreak. In the Columbretes Islands Marine Reserve (NW Mediterranean) both species coexisted until 2017, when P. nobilis populations completely disappeared. In spring 2021 we revisited 7 permanent plots covering 1,485 m2 that had been previously monitored during the period from 2005 to 2009. We found that although previous studies described P. rudis populations as stable with low recruitment rates, recruitment after 2017 increased in comparison to 2005-2009. At least two cohorts of recruits (~3 and ~1 year in age) were to be found both within the plots as well as in other areas throughout the Columbretes archipelago, colonizing areas previously occupied by P. nobilis. We hypothesize that P. rudis has been benefited by the local extinction of the sibling species P. nobilis, most probably as a result of reduced interspecific competition. The ecological role once played mainly by P. nobilis as the dominant species, might now be taken over by P. rudis, whose populations could grow during the oncoming years.