Received: 15-03-2018 / Accepted: 29-01-2019
Swollen siphon disease has been considered to be a serious threat to otter clam farmingin Vietnam; however, the cause of the disease has not been clearly understood. In this study, salinity factor (salinity concentrations of 20‰, 25‰, 30‰, 35‰ and 40‰) was selected for evaluating its impact on the survival and outbreak of the swollen siphon disease in in vivoexperiments. The results showed that the otter clams died at salinity level less than or equal to 25‰and higher or equal to 35‰. However, the dead otter clamsdid not show any clinical signs of the swollen siphon disease. The results of the experiment of otter clam injected with diseased siphon’s filtrates and maintained at different salinity conditions ranking from 20‰to 40‰showedthat the salinity was significantly associated withmortality and outbreak of the swollen siphon diseaseshowing clinical signs. This study indicated that the salinity is not the cause of the swollen siphon disease in otter clam but it may be a risk factor that was significantly associated with the outbreak of the disease, particularly high salinitylevel(higher or equal to 35‰).