The potential impacts of low and high salinities on salinity tolerance and condition index of the adult pearl oyster Pinctada imbricata radiata (Leach, 1814)

Abstract Background Salinity is one of the most consequential environmental stressors affecting marine organisms. Knowledge of salinity tolerance is of particular value to aquaculture. However, little is known explicitly about the salinity tolerance of oyster adult stage. The present study was designed to elucidate the salinity tolerance range of Pinctada imbricata radiata in order to determine the appropriate locations for grow out phase of pearl oyster culture and to assess the possibility of applying new “low salinity post-operative care” method that greatly enhance the pearl quality after implantation. The effects of extremely low and high salinities were quantified on the adult oyster survival and the ecophysiological state. Oysters were experimented in acclimated and non-acclimated sets in salinities ranged from 10 to 55 ppt (part per thousand). Results It was found that the pearl oyster has a wide tolerance range of salinity. Within the optimal salinity range (25–38 ppt), no mortality was recorded. The mortality was significantly decreased and ceased in acclimated group as compared to non-acclimated in different ranges of salinities. Condition index (CI) of oysters reared in different salinities after acclimation and without acclimation showed considerable variations in particular, at low salinities. Conclusions It is concluded that P. imbricata radiata can be reared in salinities up to 50 ppt during the growth phase. Low salinity post-operative care method can be applied on P. imbricata radiata after implantation by immersion in low salinities ranged between 20 and 25 ppt