Use of Adenylate Concentrations and Adenylate Energy Charge as Indicators of Hypoxic Stress in Estuarine Fish

Normal ATP concentrations in the white muscle of 11 different estuarine fish species varied from 3.91 to 6.59 μmol/g. Concentrations of different adenylates in the white muscle were not related to a species' natural level of swimming activity. When fish were exposed to hypoxia, ATP concentrations declined as much as 72% in some species. Decreases in ATP were not reflected in stoichiometric increases in ADP or AMP but rather in a reduction in total adenylate concentration. Sensitivity to hypoxia, expressed as changes in adenylate concentrations, was related to a species' natural level of activity and habitat preference. ATP concentration, total adenylate concentration, and adenylate energy charge appear to be useful indicators of environmental stress.