Salinity effects on plasma ion levels, cortisol, and osmolality in Chinook salmon following lethal sampling

Abstract

Studies on hydromineral balance in fishes frequently employ measurements of electrolytes following euthanasia. We tested the effects of fresh- or salt-water euthanasia baths of tricaine mesylate (MS-222) on plasma magnesium (Mg(2+)) and sodium (Na(+)) ions, cortisol and osmolality in fish exposed to saltwater challenges, and the ion and steroid hormone fluctuations over time following euthanasia in juvenile spring Chinook salmon (Oncorhynchus tshawytscha). Salinity of the euthanasia bath affected plasma Mg(2+) and Na(+) concentrations as well as osmolality, with higher concentrations in fish euthanized in saltwater. Time spent in the bath positively affected plasma Mg(2+) and osmolality, negatively affected cortisol, and had no effect on Na(+) concentrations. The difference of temporal trends in plasma Mg(2+) and Na(+) suggests that Mg(2+) may be more sensitive to physiological changes and responds more rapidly than Na(+). When electrolytes and cortisol are measured as endpoints after euthanasia, care needs to be taken relative to time after death and the salinity of the euthanasia bath.

Transcriptional Profiles of Genes Related to Stress and Immune Response in Rainbow Trout (Oncorhynchus mykiss) Symptomatically or Asymptomatically Infected With Vibrio anguillarum

“…Consistently, our studies showed significantly downregulated KEGG pathways associated with aldosterone-regulated salt and water balance (ko04960 and ko04978) (Figure 7E), indicating that ST trout show hydromineral dyshomeostasis. Previous studies in Chinook salmon (Oncorhynchus tshawytscha) showed the hydromineral balance is changed during euthanasia (111), which is consistent with our KEGG results. Based on this data, we propose positive feedback between severe infection and imminent death: (1) infection and its resulting stress response disturb the hydromineral homeostasis, thus resulting in a moribund condition.…”

Effects of Salinity on Gills’ Chloride Cells, Stress Indices and Gene Expression of Asian Seabass (Lates Calcarifer, Bloch, 1790)

“…The determination of the amounts of blood electrolytes, especially Na + , K + and Cl − , and osmolality and ion levels after changes in WS can provide information regarding the ionoregulatory ability and also successful acclimation of sh in a saline environment (Stewart et al, 2016). In the current research, the amounts of serum Na + and K + pronouncedly enhanced in sh reared at 35‰ that was associated with enhancing serum cortisol in this group indicating the increment tightening the junction between polygonal pavement cells in order to limit passive salt gain or loss during SW or FW acclimation, respectively (Chasiotis et al, 2012).…”

Physiological responses to salinity stress in the Managua Cichlid,Cichlasoma managuense

“…Exposure to fresh, brackish or salt water imposes a concentration gradient between the environment and the organism, and NKA activity plays an important role in maintaining homeostasis. Many recent data demonstrated that salinity has strongly increased NKA activity in many fish (Laverty & Skadhauge, 2012), such as spottedtail goby Synechogobius ommaturus (R.) (Shui et al., 2018), European sea bass Dicentrarchus labrax (Sinha et al., 2015) and Chinook salmon ( Oncorhynchus tshawytscha ; Stewart et al., 2016), while a few studies still suggested that the effects of salinity on branchial NKA activity were not significant (Kelly, Chow, & Woo, 1999; Yoshikawa, McCormick, Young, & Bern, 1993). Another more complex pattern of branchial NKA activity is that the lowest value is found in the salinity closed to their iso‐osmotic point (Shui et al., 2018; Urbina & Glover, 2015).…”

“…Similarly, the HPS90 levels of fish in muscle for the 6 and 9‰ salinity treatments at 192 hr time point were the lowest points although they were not statistically different (p > .05; Figure 4b). goby Synechogobius ommaturus (R.) (Shui et al, 2018), European sea bass Dicentrarchus labrax (Sinha et al, 2015) and Chinook salmon (Oncorhynchus tshawytscha; Stewart et al, 2016), while a few studies still suggested that the effects of salinity on branchial NKA activity were not significant (Kelly, Chow, & Woo, 1999;Yoshikawa, McCormick, Young, & Bern, 1993). Another more complex pattern of branchial NKA activity is that the lowest value is found in the salinity closed to their iso-osmotic point (Shui et al, 2018;Urbina & Glover, 2015).…”