DAO prepress abstract  -  DOI: https://doi.org/10.3354/dao03339

Prevalence of nervous necrosis virus and Streptococcus species in wild marine fish and crustaceans from the Levantine Basin, Mediterranean Sea

Ran Berzak, Aviad Scheinin, Nadav Davidovich, Yael Regev, Rei Diga, Dan Tchernov, Danny Morick*

*Email: dmorick@univ.haifa.ac.il

ABSTRACT: The abundance and prevalence of infectious diseases in marine animals have ecological, socio-economic and environmental impacts. Nervous necrosis virus (NNV) and Streptococcus iniae have come to be a major threat to marine aquaculture and have been detected in morbid marine organisms worldwide. However, despite their importance, there is lack of knowledge regarding those pathogens prevalence in wild fish species. From the eastern Mediterranean, indigenous and Lessepsian species from different trophic levels and different biological niches were sampled. A total of 174 fish and 32 crustaceans were tested for S. iniae and a total of 195 fish and 33 crustaceans were tested for NNV. We found an overall prevalence of 9.71% Streptococcus species and 21.49% NNV in selected marine fish and crustaceans by PCR and qPCR. Streptococcus iniae, a zoonotic agent, was detected in a higher prevalence in kidney compared to liver tissue, in positive fish samples. Co-infection of both pathogens was detected only in five specimens. We also examined in this study, gilthead sea bream (Sparus aurata) from an Israeli offshore marine farm during its grow-out period, in order to assess the possibility of horizontal pathogens transmission from wild fish to maricultured fish. Three out of 15 (20%) fish were found to be NNV positive after 120 days in the sea, suggesting spontaneous transmission from wild to farm fish. Our findings suggest that more of such surveys should be performed, especially in areas were mariculture farms are planned to be established.