Water chemistry and its effects on the physiology and survival of Atlantic salmon Salmo salar smolts

Abstract

The physiological effects of episodic pH fluctuations on Atlantic salmon Salmo salar smolts in eastern Maine, U.S.A., were investigated. During this study, S. salar smolts were exposed to ambient stream-water chemistry conditions at nine sites in four catchments for 3 and 6 day intervals during the spring S. salar smolt migration period. Plasma chloride, plasma glucose, gill aluminium and gill Na + -and K + -ATPase levels in S. salar smolts were assessed in relation to ambient stream-water chemistry during this migration period. Changes in both plasma chloride and plasma glucose levels of S. salar smolts were strongly correlated with stream pH, and S. salar smolt mortality occurred in one study site with ambient stream pH between 5·6 and 5·8 during the study period. The findings from this study suggest that physiological effects on S. salar smolts are strongly correlated with stream pH and that in rivers and streams with low dissolved organic carbon (DOC) concentrations the threshold for physiological effects and mortality probably occurs at a higher pH and shorter exposure period than in rivers with higher DOC. Additionally, whenever an acidification event in which pH drops below 5·9 coincides with S. salar smolt migration in eastern Maine rivers, there is potential for a significant reduction in plasma ions of S. salar smolts. Journal of Fish Biology

Evidence for episodic acidification effects on migrating Atlantic salmon Salmo salar smolts

“…River discharge was low during this time, and there is no evidence of acidification at either location. This interannual variability in pH and environmental aluminium in rivers in Maine was also noted in a previous study of acid and aluminium exposure of hatchery-reared smolts exposed to natural river water from four catchments in Maine including the Narraguagus River (Liebich et al, 2011). In that study, low pH conditions in 2005 were associated with high discharge and negative physiological effects on smolts (reduced plasma ions and elevated glucose), but in years without high discharge, low pH and physiological effects were absent.…”

Aluminum exposure impacts brain plasticity and behavior in Atlantic salmon (Salmo salar)

“…In the present study, Acid-Al fish had higher levels of both plasma glucose and cortisol than control fish, suggesting a higher stress level due to activation of the endocrine hypothalamic-pituitary-interrenal (HPI) axis. The effects of acidification on Atlantic salmon have been studied and, similarly, it was found that low pH was strongly correlated with negative physiological effects (Liebich et al, 2011). Thus in the present study, fish exposed to Al toxicity in acidic water will have experienced high allostatic load through physiological changes associated with the HPI axis, which may have led to the observed changes in learning behavior.…”

Assessment of Early Migration Dynamics of River‐Specific Hatchery Atlantic Salmon Smolts

“…Since the removal of dams, exploitation from fisheries, point source pollution (e.g., hazardous waste dump sites), non-point-source pollution (fertilizers, pesticides, toxic chemicals, sediment, etc. ; Beland et al 1982; Bartlett and Robinson 1988;Arter 2005), impacts from weather-induced acidification (Liebich et al 2011), predation (Baum 1997), poor marine survival (ICES 2016;USASAC 2017), and climate change (Jonsson and Jonsson 2009) have been considered factors contributing to the observed declines of Atlantic Salmon within this system.…”