Changes in growth and osmoregulation during acclimation to saltwater in juvenile Amur sturgeon Acipenser schrenckii |
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| Authors: | Feng Zhao Ping Zhuang Longzhen Zhang Junli Hou |
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| Institution: | (1) Department of Fisheries, College of Natural Resources, Khorramshahr University of Marine Science and Technology, P.O. Box 669, Khorramshahr, Khuzestan, Iran;(2) Faculty of Veterinary, Shahid Chamran University, Ahvaz, Khuzestan, Iran;(3) Marine Living Science Department, Iranian National Center for Oceanography (INCO), Tehran, 1411813389, Iran; |
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| Abstract: | We evaluated the ability of juvenile Amur sturgeon (Acipenser schrenckii) to osmoregulate and grow in saltwater. Hatchery-reared juveniles (mean weight 106.8 g, 5-month old) were transferred from
freshwater to 10, 20, and 25 salinity saltwater over a period of 20 d. We measured the growth, serum osmolality, ion concentrations,
and Na+/K+-ATPase activity. In addition, we prepared samples of gill tissue to quantify morphological changes in gill ultrastructure.
Rearing in up to 25 saltwater for 30 d had no significant effect on growth. Similarly, serum osmolality and ion concentrations
were similar to levels reported in other teleosts following acclimation to saltwater. Serum osmolality and Na+, Cl− concentrations increased significantly with the initial increase in salinity. Afterwards, levels tended to stabilize and
then decrease. Serum K+ levels did not change during acclimation to saltwater. Gill Na+/K+-ATPase activity increased initially as salinity was increased. However, the activity later decreased and, finally stabilized
at 3.7±0.1 μmol Pi/mg·prot·h in 25 saltwater (1.6 times higher than the level in those in freshwater). In fish that were held only in freshwater,
the chloride cells were located in the interlamellar regions of the filament and at the base of the lamella. Following acclimation
to 25 saltwater for 30 d, the number and size of chloride cells increased significantly. Our results suggest that juvenile
Amur sturgeon is able to tolerate, and grow in, relatively high concentrations of saltwater. |
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