Research Information System
Diseases of aquatic organisms, vol.166, pp.1-6, 2026 (SCI-Expanded, Scopus)
Fan mussels Pinna nobilis across the Mediterranean Sea have been severely impacted by a widespread mass mortality event, largely attributed to Haplosporidium pinnae. While the Sea of Marmara (SoM) has historically served as a refuge for this Critically Endangered species, recent findings suggest the emergence of various pathogens, including haplosporidian parasites, in SoM populations. This study presents the first confirmed case of H. pinnae infection in fan mussels from the southern SoM, with a focus on species-level identification, and contributes to growing concerns about the potential spread of this pathogen into previously unaffected regions. On 23 November 2024, 5 live fan mussels were collected from depths of 2.3-6.5 m in the southern SoM. Histopathological examination revealed structural alterations in the mantle tissue and the presence of plasmodial stages of H. pinnae. Molecular analyses further confirmed the presence of H. pinnae in several samples, exhibiting 100% sequence similarity with isolates from other Mediterranean regions. This study provides essential evidence of infection in the SoM and underscores the need for continued monitoring and conservation efforts for fan mussel populations in the region, especially as pathogens continue to spread across the Mediterranean Sea. The results represent a significant conservation alarm and highlight the urgent need for continued pathogen surveillance, early warning strategies, and robust management interventions in one of the last strongholds of this keystone species.