Effects of sulfate-type saline-alkaline water on growth performance and osmoregulation in juvenile Daiqu strain large yellow croaker (Larimichthys crocea)

This study evaluated the effects of sulfate-type saline-alkaline water on the growth performance and osmotic homeostasis of juvenile L. crocea. This study focused on L. crocea that had been acclimated to low-salt conditions. The low-salt group (LS) was used as the control, the seawater group (SW) and the sulfate-type saline-alkaline water group (AW) were established as treatment groups. The changes in physiological indicators within 96 hours of acute stress in L. crocea were analyzed, and the growth performance indicators of the two treatment groups were compared. During the 36-day feeding experiment, there was no significant difference in growth performance between the AW group and the SW group (P > 0.05). However, the survival rate of the AW group (43.33%±4.06%) was significantly lower than that of the SW group (96.00%±1.15%) (P < 0.05). The 96-hour acute exposure experiment further elucidated the physiological adaptive responses of L. crocea to distinct aquatic environments. In seawater, blood osmolality of L. crocea increased significantly within 6 h of exposure and subsequently stabilized at an elevated level. In contrast, AW group elicited a markedly divergent response: osmolality increased significantly after 48-72 h of exposure, gradually recovered to baseline levels by 96 h. Ionoregulatory adjustments in AW group were characterized by pronounced perturbations in K⁺ and Ca²⁺ homeostasis. Cl⁻ concentration rose significantly at 72 h and returned to baseline by 96 h. The SW group showed a marked increase in pCO₂ and bicarbonate-related parameters during the early exposure phase, followed by a gradual decline and subsequent stabilization. Overall, our findings indicate that the growth performance of juvenile L. crocea in sulfate-type saline-alkaline water is slightly lower than that in seawater. In the short term, juveniles can acclimate to such environments via endogenous osmoregulatory mechanisms. However, during long-term culture, elevated sulfate concentrations disrupt homeostasis of key blood ions and ultimately resulting in mortality. This study provides foundational data to support the domestication and aquaculture development of this species in such marginal aquatic environments.