Evaluation of the health of Mediterranean mussels (<i> Mytilus</i> galloprovincialis Lamarck, 1819) distributed in the Çanakkale strait, Turkey

The observation of mortality in Mediterranean mussels ( Mytilus galloprovincialis ) distributed in the & Ccedil;anakkale Strait in recent years was influential in developing the research question for this study. In this study, the presence of bacteria ( Vibrio spp.) and parasites ( Marteilia spp. and Haplosporidium spp.) in mussels collected from Kumkale, Kepez, and Umurbey stations in the & Ccedil;anakkale Strait was investigated seasonally. Microbiological findings, histopathology, oxidative stress enzymes and their gene expressions, lipid peroxidation, lysosomal membrane stability, and changes in haemolymph were examined. In summer samples, both the defence system and the extent of damage were higher in gill tissue. In winter samples, enzyme activities and lipid peroxidation were found to be predominantly higher in digestive gland tissues. Histological examinations and Hemacolor staining revealed the presence of protozoan cysts, and for bacterial examination, molecular analysis performed after culturing revealed the presence of 7 Vibrio species. While the total numbers of heterotrophic bacteria detected in all samples were at acceptable levels, the predominance of Vibrio spp. numbers among the total heterotrophic bacteria detected in almost all samples were noteworthy. The total hemocyte count was calculated as 5.810(4) +/- 0.58 (cells/mm 3 ) in winter and 7.210(4) +/- 1.03 (cells/mm 3 ) in summer. These factors are considered to be possible causes of mussel mortality.