Regulation of Drinking Rate in Euryhaline Tilapia Larvae (Oreochromis mossambicus) during Salinity Challenges

Abstract

Euryhaline tilapia larvae are capable of adapting to environmental salinity changes even when transferred from freshwater (FW) to seawater (SW) or vice versa. In this study, the water balance of developing tilapia larvae (Oreochromis mossambicus) adapted to FW or SW was compared, and the short-term regulation of drinking rate of the larvae during salinity adaptation was also examined. Following development, wet weight and water content of both SW- and FW-adapted larvae increased gradually, while the dry weight of both group larvae showed a slow but significant decline. On the other hand, the drinking rate of SW-adapted larvae was four- to ninefold higher than that of FW-adapted larvae from day 2 to day 5 after hatching. During acute salinity challenges, tilapia larvae reacted profoundly in drinking rate, that is, increased or decreased drinking rate within several hours while facing hypertonic or hypotonic challenges, to maintain their constancy of body fluid. This rapid regulation in water balance upon salinity challenges may be critical for the development and survival of developing larvae.

Salinity-Dependent Shift in the Localization of Three Peptide Transporters along the Intestine of the Mozambique Tilapia (Oreochromis mossambicus)

“…The phenomena of salinity-dependent localization shift toward the distal sections of the intestinal tract could be due to the fish higher drinking rate in saltwater than in freshwater, resulting in rapid movement of nutrients down the intestine (Bucking et al, 2011; Grosell, 2011; Lin et al, 2013). Alternatively, this could be a result of a complex regulation of the interacting osmoregulatory and nutritional functions of the intestine.…”

Intestinal Na + , K + , 2Cl − cotransporter 2 plays a crucial role in hyperosmotic transitions of a euryhaline teleost

“…As a point of comparison, acute transfer of killifish (F. heteroclitus) from isosmotic water to seawater resulted in a peak drinking response after only 12 h (Scott et al 2008). Similarly, larval tilapia showed increased drinking rates within hours of a hyperosmotic challenge (Lin et al 2001). This study only provides indirect evidence of drinking; however, these data still clearly demonstrate that the drinking response in red drum is more slowly initiated than that described for other species.…”

“…Similarly, larval tilapia showed increased drinking rates within hours of a hyperosmotic challenge (Lin et al. ). This study only provides indirect evidence of drinking; however, these data still clearly demonstrate that the drinking response in red drum is more slowly initiated than that described for other species.…”

Water balance trumps ion balance for early marine survival of juvenile pink salmon (Oncorhynchus gorbuscha)

“…This acclimation period was deemed suYcient as alevins and fry were almost entirely motionless in chambers at trial onset and not observed to be hyperventilating. Furthermore, many studies with larval Wshes forego an acclimation period altogether (Tytler et al 1990;Fuentes and Eddy 1996;Lin et al 2001). At trial onset, 90 Ci of [ 3 H]-polyethylene glycol (PEG-4000; American Radiolabeled Chemicals Inc., St. Louis, MO, USA) was added to the system and 5 mL of water sampled.…”