NUCLEOTIDES AND THE ADENYLATE ENERGY-CHARGE AS INDICATORS OF STRESS IN RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) SUBJECTED TO A RANGE OF DISSOLVED-OXYGEN CONCENTRATIONS

Liver nucleotides (ATP, ADP, AMP, IMP), the adenylate energy charge (A EC), total adenylate concentration (TA), and IMP-load were used as mea sures of stress in rainbow trout (Oncorhynchus mykiss) acclimated to n ormoxic (10.0 mg/1), hypoxic (6.5 mg/1), and supersaturated (13.0 mg/1 ) dissolved oxygen concentrations and subjected to a challenge by conf inement. Liver ATP (783.0 nmol/g) was significantly different in the n ormoxic fish compared to either hyperoxic (447.7 nmol/g) or hypoxic (4 02.0 nmol/g) fish at the end of the confinement. Within 6.0 hr in the confinement, liver AEC in the normoxic fish increased significantly (0 .58) compared to hypoxic (0.42) and hyperoxic fish (0.42). Similarly, the IMP-load in normoxic fish (0.16) decreased to near prestress level s by 6.0 hr in confinement compared to either the hypoxic (0.31) or hy peroxic (0.30) fish. Nucleotides in Liver were significantly affected by the dissolved oxygen treatments and the confinement stress in contr ast to the muscle nucleotides which were not.