Rainbow trout (Oncorhynchus mykiss) exposed to oxygen supersaturation and handling stress: plasma cortisol and hepatic glutathione status.
Three groups of one summer old rainbow trout were exposed for 22 days either to normoxia (100%) or moderate oxygen supersaturation; 120% and 140%. After the exposure, all groups were transported for three hours in hyperoxic conditions (123% O2) thus simultaneously experiencing density and handling stress. The recovery of rainbow trout to multiple stressors was measured in normoxic conditions. Moderate oxygen supersaturation did not have any negative effects on growth, feed conversion and blood hematology measured over 22 days. On the other hand, the combined effects of the stressful environment in the fish farm and oxygen supersaturation resulted in a 3-fold increase in plasma cortisol levels in those with 100% and 120% O2 supersaturation and a 2-fold increase in the 140% supersaturation group. Furthermore, the stress response after transportation was lowest in the 140% group 24 hours after recovery but highest after 70 hours. Moderate hyperoxia or transportation stress did not change glutathione concentrations in liver indicating that routine sampling does not affect hepatic glutathione status. Our results indicate that moderate O2 supersaturation (<140%) could be considered as feasible in cultivation of rainbow trout since no harmful effects were found.
Ritola
O
O
Department of Physiology, University of Kuopio, Finland. Ossi.Ritola@uku.fi
Kiuru
T
T
Koponen
K
K
Mölsä
H
H
Hänninen
O
O
Lindström-Seppä
P
P
D000818:Animals; D017756:Aquaculture; D005978:Glutathione / Q000378:metabolism*; D006854:Hydrocortisone / Q000097:blood*; D008099:Liver / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000254:growth & development / Q000502:physiology; D010100:Oxygen / Q000506:poisoning*; D013312:Stress, Physiological
D005978:Glutathione; D010100:Oxygen; D006854:Hydrocortisone