of Beiningen (1973) and Ebel (1969). Weekly mea- 

 surements of total alkalinity (16 to 20 ppm), total 

 hardness (10 to 21 ppm), carbon dioxide (1.2 to 

 2.0 ppm), chlorine + chloramine (<0.02 ppm) and 

 pH (6.8 to 7.3) were made according to Tarus et al. 

 (1971). Calcium (6.4 to 6.7 ppm) and potassium 

 (0.3 to 1.0 ppm) were determined monthly by flame 

 spectrophometer (Dawley and Ebel, MS). 



RESULTS 



Alteration from control mean values (>3o) were 

 observed in 7 of 16 blood characteristics in juvenile 

 steelhead exposed to 116.0% nitrogen saturation, 

 while meaningful changes in these 16 substances 

 were not noted at lower saturations (Fig. 1). An 

 increase in concentrations of potassium and phos- 

 phate were noted at 116.0% nitrogen saturation, 

 while decreases in concentration were noted in 

 albumin, calcium, cholesterol, AP-ase and total 

 protein. Decrease in serum calcium was positively 

 correlated with decreases in cholesterol (r = 0.86; 

 P < 0.05) and albumin (r = 0.95; P < 0.01), and 

 negatively correlated with an increase in potassium 

 (r= -0.77; P < 0.05). 



« ~T Q ; 



~4 r- O 



1.60 



§, 1.40 - 



z 



| 1.20- 



CO 



* 1.00 

 11.0 



E10.0 



s 



3 9.0 

 < 

 o 

 8.0 



* 300 



£ 



- 250 



o 



5 150 



* 3.5 



E 

 Oi 



z 3.0 - 



| 



9= 2-5 r- 



rfi 



JZL 



14.5 



14.0 



nn rt. 



± 13.5 



o 



£ 13.0 



_, 4-5 r 



f 4.0 



< 



§ 3.0 



150 



^5- 100 



-■ < E 



iS5 e 50 



n n 



< o 



2.0 



m 



In addition to potassium, a decrease in albumin 

 was negatively correlated with an increase in 

 phosphate (r= -0.82; P < 0.05), and positively corre- 

 lated with decreases in cholesterol (r = 0.97; P < 0.01) 

 and total protein (r = 0.90; P < 0.01). 



No correlation (P < 0.5) could be drawn between 

 oxygen, nitrogen or TCP saturation and mean weight 

 or length. 



A 46% incidence of external gas bubble disease 

 signs were noted in steelhead exposed to 116.0% 

 nitrogen saturation, while no external signs were 

 observed at lower saturations. These signs were 

 largely in the form of lateral line bubbles with a 

 lower incidence of blebs appearing in the dorsal 

 and caudal fins. No mortalities occurred during 

 these tests (Dawley and Ebel, MS). 



DISCUSSION 



It is important to distinguish between blood 

 chemistry changes due to chronic as opposed to 

 acute (short-term) stressors (Wedemeyer, 1970b). 

 Much of the literature on salmonid blood chemistry 

 is concerned only with acute stressors; those applied 

 over 1 hr to 1 week (Cardwell et al., 1970; Miles 

 and Smith, 1968; and Wedemeyer, 1970, 1971, and 

 1972). Because no mortality occurred over the 35-day 

 test at 116% nitrogen (110% TGP), the author only 

 considered chronic stressor responses in this discus- 

 sion. The chronic stress noted at 110% TGP is 

 particularly significant because 110% TGP saturation 

 is the level presently suggested by EPA as a pro- 

 visional water quality standard (Rulifson,* personal 

 communication). 



Two mechanisms have been invoked in an 

 attempt to explain gas bubble disease. These 

 mechanisms are gas embolism of the heart, gills 

 or other vital portions of the blood system (Marsh 

 and Gorham, 1905; and Dawley and Ebel, MS), and 

 starvation due to blebs in the lining of the mouth 

 preventing ingestion of food (Dawley and Ebel, MS). 

 A 50% reduction in serum glucose was indicated 

 by Robertson et al., 1962, when rainbow trout were 

 starved. Similarly, albumin (Booke, 1964) and total 

 protein (Phillips et al., 1960) decreased in brook 

 trout, Salvelinus fontinalis. 



Emboli may be envisioned to block arteries and 

 veins in a variety of critical tissues and organs, 

 which would result in local or systemic hypoxia, 

 respiratory acidosis and necrosis from the buildup 

 of toxic wastes. The gills, brain, heart and kidney 

 are four such critical sites. Short-term hypoxia was 



FIG. 1 Major serum chemistry parameters with increasing 

 N 2 ♦ Ar saturations. Control (103.5% N 2 + Ar) values are mean 

 and range. 



*R. L Rulifson, Fishery Biologist, Environmental Protection 

 Agency, Seattle, Washington. 



98 Newcomb 



