Electrolyte balance and energy mobilization in acid-stressed rainbow trout, Salmo gairdneri , and their relation to reproductive success
Synopsis: The main objective of the research was to learn whether selected physiological responses could be used as symptoms of forthcoming reproductive impairment in fishes subjected to acid stress. Electrolyte balance (Na+, Cl?) in blood and muscle, plasma osmotic pressure, internal water balance, blood glucose and liver glycogen were the most important parameters measured in rainbow trout, Salmo gairdneri, exposed for two — three weeks at six pH levels: 8.3, 7.7, 7.0, 6.2, 4.8, 4.2. In general, plasma and muscle Na+/Cl? and plasma osmotic pressure declined sharply at higher acidifies while energy mobilization responded in the opposite fashion. The data were interpreted in terms of zones of tolerance and resistance. The zone of tolerance lies between pH 9.0 and 5.0, while the zone of resistance extends beyond pH 5.0. Complete regulation of physiological parameters occurred between the highest measured pH, 8.3, and 6.0. The limits of partial regulation and loss of regulation were tentatively set between pH 6.0 and 5.0 for the former and beyond 5.0 for the latter. Environmental and genetic factors are known to shift these limits. Reproductive stress occupies a zone between pH 5.5 and 6.5, according to laboratory and field observations on several species. The zone of reproductive stress overlaps the limits of complete and partial regulation. The physiological parameters therefore, would not be expected to exhibit consistently recognizable and dependable changes that would be useful to forecast reproductive failure. Severe acid stress could be diagnosed with the symptoms, however. A field test of the findings was provided by blood and tissue samples of white suckers, Catostomus commersoni, from an acidified (pH 5.2) and an unacidified (pH 7.2) lake in the Adirondack Mountains, Herkimer County, New York. Changes in electrolytes and glucose-glycogen, predicted from the laboratory experiments, were noticed in fish from the acidified lake, although the changes were not striking. These fish may have been in a physiological state of partial regulation within the zone of tolerance.
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences biologiques fondamentales et appliquees. psychologie
- 1 - Life Sciences ; 2 - Agricultural and Biological Sciences ; 3 - Aquatic Science
- 1 - Life Sciences ; 2 - Agricultural and Biological Sciences ; 3 - Ecology, Evolution, Behavior and Systematics