The effect of extended wet-storage on the condition, physiology and stress response of cultured blue mussels (Mytilus edulis L. 1758) during summer and fall in northeastern Newfoundland

In order to determine the effects of extended wet-storage under ambient conditions we investigated the physiological response of blue mussels held for up to 3 months in a commercial holding facility. During the summer and the fall there was a significant decline in dry weight and condition of mussels held over time when compared to field controls. Neutral red retention time decreased significantly in holding for both seasons but not in the field controls, indicating an increase in stress response for held mussels. Little variation was noted in the expression of the oxidative stress genes superoxide dismutase and GSH-peroxidase during the summer or fall regardless of treatment. Expression of the antimicrobial peptide MGD2 was evident in the summer holding samples as early as 1 week but did not occur in the fall holding samples until 3 months. This suggests that holding conditions have stimulated the immune response in a manner potentially related to time in holding and environmental temperature. Based on our results we recommend that one month should be the maximum time allowable in ambient extended holding during warm water seasons. During the warmest part of the summer this could be reduced to two weeks.

► Evaluation of the physiological effects of extended holding on cultured mussels
► Morphometrical parameters and condition index were compared.
► Studied physiological stress and immune response via neutral red assay and RT PCR
► Ambient holding system gave decreased dry tissue weight and condition index.
► Seasonal stress acute for mussels in holding; 1 month max in holding recommended