Mass mortality in endangered fan mussels Pinna nobilis (Linnaeus 1758) caused by co-infection of Haplosporidium pinnae and multiple Vibrio infection in Çanakkale Strait, Turkey

Abstract

Purpose

Pinna nobilis (fan mussel) is one of the most important endemic bivalve molluscs in the Mediterranean and mass mortality events were observed in these mussels in recent years. In this study, we report mass mortalities caused by Haplosporidium pinnae, which has been spreading in the Mediterranean for 3 years, and reached the Çanakkale Strait, which is the entrance of the Marmara and the Black Sea.

Material and methods

Field observations during sampling and subsequent histopathological, biochemical, genetic, and microbiological analyses were carried out.

Results

These analyses showed that H. pinnae infection spread among the natural beds of P. nobilis, causing severe tissue damage and oxidative stress. Our phylogenetic analyses suggested that the parasite spread through the Mediterranean much faster than thought. The results showed that vibriosis originating from Vibrio coralliilyticus, Vibrio tubiashii, Vibrio mediterranei, and Vibrio hispanicus, acted together with H. pinnae in infected individuals and caused death.

Conclusion

It is highly probable that the spread of H. pinnae to the Sea of Marmara and the Black Sea may occur earlier than expected, and it was concluded that mass deaths were caused by co-infection with H. pinnae and a geographically specific marine pathogen that can infect P. nobilis populations.

Keywords:

• Pinna nobilis
• Haplosporidium pinnae
• Vibrio
• histopathology
• oxidative stress
• mass mortality event

Authors’ contributions

İEK was involved in the microbiological analyses, writing of manuscript, editing, and finalization. SEG was involved in the antioxidant enzyme analyses, writing of manuscript, editing, and finalization. AA was involved in the visual observations. ET was involved in the molecular analyses, writing of the manuscript; editing. FÇ was involved in the work plan of this study. MG was involved in the histopathological analyses, writing of manuscript editing, and finalization. UA was involved in the visual observations, writing of the manuscript, statistical design and analysis, study administration. All authors read and approved the final manuscript.

Ethical approval

The samples were collected with permits from the Ministry of Agriculture and Forestry of the Turkish Republic (28.04.2020/39871594-600-E.2000061639).

Acknowledgements

We thank Terje M. Steinum for his helpful suggestions in phylogenetic analyses.

Disclosure statement

No potential conflict of interest was reported by the author(s).