^L~.~^~^ :— * ■ T. W. Newcomb 



Changes in ■ 



Blood Chemistry 



of Juvenile 



Steeihead, Salmo gairdneri, 



Following Sublethal Exposure 



to Nitrogen Supersaturation 



ABSTRACT 



Groups of juvenile steelhead trout (Salmo gairdneri) were exposed 

 for 35 days to various (103, 105, 110, and 116% sublethal 

 nitrogen plus argon saturations. Pooled serum samples were 

 analyzed for Ca, Na, POa, K, CI, albumin, total protein, choles- 

 terol, alkaline phosphatase, glucose, urea, uric acid, total bili- 

 rubin, lactate dehydrogenase and serum glutamic oxalacetic 

 transaminase. An increase in serum potassium and phosphate, 

 and a decline in serum albumin, calcium, cholesterol, total 

 protein and alkaline phosphatase were noted in steelhead ex- 

 posed to 116% nitrogen (N 2 + Ar) saturation (total atmospheric 

 gas saturation 110%). No major changes in blood chemistry were 

 observed at nitrogen saturations of 110% or less. 



One major water pollution problem of the Colum- 

 bia and Snake Rivers is atmospheric gas super- 

 saturation which produces gas bubble disease in 

 fish. 



Gas emboli form in the fish's supersaturated 

 blood in some as yet undefined manner (D'Aoust,* 

 personal communication). Gas emboli may then 

 lodge at a variety of sites throughout the fish's body. 

 These emboli can then limit delivery of oxygen 

 and removal of carbon dioxide and toxic metabo- 

 lites from the affected tissues and organs. Persis- 

 tence of this physiological condition will lead to the 

 ultimate death of the fish. 



A number of mortality studies with nitrogen 

 gas supersaturation have been made on juvenile 

 salmonids, but little work has been published on 

 the sublethal effects (Dawley and Ebel, MS). Sub- 

 lethal effects from gas supersaturation may cause 

 alterations in the fish's blood chemistry which can 

 be used as tools to determine the degree of stress. 

 These blood chemical measurements may help pin- 



96 



point potential long-range problems encountered 

 by the juvenile salmonid such as ingestion and 

 assimilation of food, predator avoidance, locomo- 

 tion, homing behavior, fecundity, and the quantity 

 and quality of subsequent fertilized eggs and fry. 

 In addition, measuring these blood chemistry char- 

 acteristics may allow in situ evaluation of nitrogen 

 gas supersaturation stress response both singly and 

 in combination with other normally-occurring 

 stressors (e.g. passage through turbines) which 

 occur to the juvenile salmonid on its downstream 

 migration. 



This blood chemistry experiment represents 

 an extension of a bioassay by Dawley and Ebel (MS) 

 which was designed to provide a variety of lethal 

 and sublethal biological criteria which would help 

 form the basis for an EPA provisional water quality 

 standard. The primary goal was the establishment 

 of a series of LD50 values. Secondary goals were 

 changes in voluntary swimming performance and 

 blood chemistry characteristics which might give 

 some estimate of sublethal stress response to gas 

 bubble disease. 



MATERIALS AND METHODS 



The fish used in these experiments were steel- 

 head trout, Salmo gairdneri, provided by the Wash- 

 ington State Department of Game Hatchery at 



Newcomb: National Marine Fisheries Service, Seattle, Wash- 

 ington. 



*B. C. D'Aoust, Research Biologist, Hyperbaric Laboratory, 

 Virginia Mason Research Center, Seattle, Washington. 



