The knowledge on the effect of different stress factors on Atlantic salmon, Salmo salar Linnaeus, 1758, is far from complete and therefore we decided to find out how the low water level stress could effect pathophysiological parameters such as: plasma cortisol level, haemoglobin, haematocrit, chloride (Cl–), sodium (Na+), osmolality, lactate, and glucose in this fish; and how this stressor affects the gut morphology. Two hundred and four juvenile Atlantic salmon were randomly distributed into six fibreglass tanks and divided into two groups: group 1 (control) and group 2 (low water level stress). The low water level stress did not affect growth performance and the pathophysiological parameters. Light- and transmission electron microscopy evaluations of the pyloric caeca and the distal intestine revealed that chronic stress had no effect on gut morphology. Low water level stress had no clear effects on pathophysiological parameters and gut morphology of Atlantic salmon.

chronic and acute stress, Atlantic salmon, haematological parameters, gut, light microscopy, transmission electron microscopy