Intestinal response to salinity challenge in the Senegalese sole (Solea senegalensis)

Environmental Salinity Affects Growth and Metabolism in Fingerling Meagre (Argyrosomus Regius)

“…Plasma osmolality did not vary between 12 ppt (271 ± 2 mOsm kg −1 ) and 39 ppt (274 ± 3 mOsm kg −1 ). A range of different salinities from 5 to 39 ppt were prepared with the seawater and the freshwater employed in this study, and the results were in accordance with previous studies performed by our research group [17,30,35,36] with 161, 343, and 1159 mOsm kg −1 for the salinities of 5, 12, and 39 ppt. As the water osmolality increased with environmental salinity (within the range from 5 to 39 ppt) fitting in a straight regression line (r 2 = 0.994, p < 0.05), and no variations were found in plasma osmolality between fish acclimated to both experimental salinities (12 and 39 ppt), we substituted the average plasma osmolality calculated for fingerlings (273 ± 2 mOsm kg −1 ) in the regression line calculated for water osmolality, thus resulting in an iso-osmotic salinity for A. regius fingerlings of 9.2 ppt.…”

“…Thus, ionocyte cells in osmoregulatory tissues may show differentiated ion-transport mechanisms rather than the NKA enzyme, highlighting the importance of further studies on this topic to fully elucidate the relative importance of osmoregulation on body growth. Moreover, this study did not measure drinking rates, which is an energetically costly mechanism that involves digestive tract desalinization to maintain plasma osmolality at high environmental salinities, and includes changes in the population of intestinal cells [36]. In light of the results from this study, it is not clear that osmoregulatory processes at 39 ppt salinity consume more energy that at 12 ppt, though fish growth is faster at the latter salinity.…”

“…The branchial and renal Na + /K + -ATPase (NKA) enzyme, an important modulator of osmoregulatory processes that is responsible for major energy expenditures during osmoregulation [15,31,36,41], exhibited no changes between 12 and 39 ppt salinity. This result was similar to that previously described for other teleost species, such as Sparus aurata [41], and reflects that other osmoregulatory tissues such as the intestine have important roles in the maintenance of body fluids, as described before in Solea senegalensis and Galaxias maculatus [36,42]. Thus, ionocyte cells in osmoregulatory tissues may show differentiated ion-transport mechanisms rather than the NKA enzyme, highlighting the importance of further studies on this topic to fully elucidate the relative importance of osmoregulation on body growth.…”

Narrowing the Range of Environmental Salinities Where Juvenile Meagre (Argyrosomus regius) Can Be Cultured Based on an Osmoregulatory Pilot Study

“…This euryhaline response coincides with what was described in the sciaenid shi drum, Umbrina cirrosa [34], the European seabass, Dicentrarchus labrax [35] and the sub-Antarctic Eleginops maclovinus [36]. However, other euryhaline species cultured in Europe such as Sparus aurata, Dicologoglossa cuneata and Scophthalmus maximus manage to maintain constant plasma osmolality levels within a narrower range of salinities, from brackish water close to the iso-osmotic point of these species to seawater [23,37,38], while Solea senegalensis, Scophthalmus rhombus and Pagrus pagrus show increasing plasma osmolality as environmental salinity increased [39][40][41].…”

“…This enzyme is placed in the basolateral membrane of specialized branchial cells called chloride-cells, or mitochondrial-rich cells, or ionocytes. These cells actively secrete ions (mainly Na + and Cl − ) through the branchial epithelium energized mainly by NKA in hyperosmotic environments, while actively absorb these ions in hypo-osmotic environments in collaboration with other basal/apical ion transporters/channels [41]. In this sense, extreme salinities induce two different NKA profiles depending on the species.…”