Acclimation potential of Acipenser persicus post-larvae to abrupt or gradual increase in salinity

Besides commercial aquaculture another major aim of sturgeon culture is in support of restocking programmes. Identifying the appropriate size, age and location for release of post-larvae or fingerlings is very important to achieve success. We investigated the potential acclimation ability of Acipenser persicus post larvae (245 +/- 21.53 mg) to abrupt changes of salinity. Reared post-larvae (salinity 0.5) were exposed, either abruptly or gradually to brackish water (salinities: 2, 4, 6, 8, and approximately 12.5) for 5 days (120 h). Daily survival rate, gill chloride cell counts, and variation in glomeruli size were measured during exposure periods in both trails. These parameters were compared at the start and end of each trial. No mortality was observed during gradual adaptation to brackish water while chloride cell counts differed significantly (P < 0.05) at 6 ppt vs 12 ppt. In the gradual exposure trial, glomeruli sizes displayed a reduction with salinity increase from 8 to 12, this result was observed again between 96 and 120 h exposure to (12.5) in the abrupt exposure trial. In addition, post-larvae exposed to a gradual salinity increase had significantly higher final weights than those exposed to an abrupt salinity increase. Based on our result, it seems that A. persicus post-larvae exhibit some acclimation ability to gradual salinity change.