AMMONIA CONCENTRATIONS IN PINK 



SALMON, ONCORHYNCHUS GORBUSCHA, 



REDDS OF SASHIN CREEK, 



SOUTHEASTERN ALASKA 



Although the toxic effects of ammonia have been 

 observed in developing salmonids in hatcheries, 

 few measurements of ammonia are available from 

 the natural environment. In the fall of 1969, am- 

 monia levels in the surface waters of Sashin 

 Creek, southern Baranof Island, southeastern 

 Alaska, were measured during and after the run of 

 pink salmon, Oncorhynchus gorbuscha. Ammonia 

 levels increased significantly after the run. This 

 increase was attributed to the large number of 

 decaying carcasses of spawned-out adult salmon 

 iBrickell and Goering 1972). Low levels of am- 

 moniacal nitrogen have been found in samples of 

 intragravel waters of Sashin Creek taken in Au- 

 gust, just before most fish spawned (McNeil et al. 

 1964). Ammonia concentrations have not been 

 measured in intragravel water taken directly from 

 salmon redds with known densities of eggs or ale- 

 vins. 



The transition period just before and during 

 emergence of alevins from the gi'avel is critical for 

 survival of 3'oung salmon. The young salmon have 

 a higher rate of metabolism than eggs and early 

 alevins (Bailey et al. 1980) and are undergoing 

 physiological changes to enable them to actively 

 swim and feed rather than reside quietly in the 

 gravel. Salmonid alevins nearing the end of yolk 

 absorption excrete ammonia at a higher rate than 

 eggs or early alevins (Rice and Stokes 1975; Bailey 

 et al. 1980) and are more sensitive to ammonia 

 than earlier stages (Penaz 1965; Rice and Stokes 

 1975; Rice and Bailey 1980). At the same time 

 (winter and spring), freezing weather usually 

 causes surface and intragravel water flows to be 

 low and thus reduces the removal rate of excreted 

 ammonia. In 1972 we measured ammonia in sam- 

 ples of intragravel water taken from random sites 

 in Sashin Creek, including pink salmon redds, and 

 measured densities of live and dead alevins at each 

 sample site. In this paper we report the concentra- 

 tions of total ammonia (un-ionized and ionized) 

 found in stream and intragravel water and discuss 

 the effect of ammonia concentrations on develop- 

 ing alevins. 



Methods 

 In late March we sampled 60 random intra- 



FISHERY BULLETIN: VOL. 78. NO. 3. 1980. 



gravel sites and 4 typical surface sites. Water flow 

 in Sashin Creek was low, which was normal for 

 late March — the rainy season had not begun and 

 the winter snow was not melting. The water tem- 

 perature was 1.6' C and pH was 6.7. Samples of 

 intragravel water were taken from standpipes 

 (McNeil 1962; McNeil et al. 1964). Water samples 

 were frozen in glass bottles within 2 h of sampling 

 and kept frozen until analyzed within 3 d. 



We determined concentrations of total ammonia 

 (NH3 -I- NH4*) using an automated method that 

 quantitates the intensity of blue indophenol after 

 reaction of ammonia with alkaline phenol hypo- 

 chlorite (U.S. Environmental Protection Agency 

 [EPA] 1974). The EPA method was modified by 

 stabilizing the heat source during the reaction to 

 increase sensitivity to a detection limit of 0.004 

 ppm ammonia. Analyses were made on freshly 

 thawed water samples. Some samples and stan- 

 dards of knowTi concentration were measured, fro- 

 zen, and thawed a second time, and again 

 measured. The ammonia levels did not change, 

 indicating that our preserving technique was 

 adequate. The slightly acid water of Sashin Creek 

 aided in the retention of ammonia. 



The density of eggs and alevins was measured at 

 each site within 2 h of sampling for ammonia. We 

 sampled an area of 0.1 m^, centered on the 

 standpipe site, with a hydraulic egg-pump ( McNeil 

 1964), and counted dead eggs, live eggs, and ale- 

 vins. 



Concentrations of Ammonia in 

 Intragravel Water and its Implications 



Concentrations of ammonia and densities of 

 eggs and alevins varied widely. Total ammonia in 

 intragravel waters ranged from 0.008 to 0.240 

 ppm, and density of live eggs and alevins ranged 

 from to 352/0.1 m^ (average 21.2) (Table 1). The 

 densities of pink salmon eggs and alevins found in 

 Sashin Creek were typical of many streams in 

 southeastern Alaska'. 



The concentrations of ammonia were not corre- 

 lated with location in the stream (r = -0.18. 

 P>0.05 for ammonia concentrations measured in 



'The average densities of pink salmon alevins for 96 pink 

 salmon streams of southeastern Alaska, 1966-1974, varied from 

 <1 to 30 ale\ins/0.1 m^ (Kingsbury, A., P. Larson, and G. Dow- 

 ney. 1975. Forecast ofthe 1975 pink salmon returns to south- 

 eastern Alaska. Alaska Dep. Fish Game, Inform. Leafl. 168, 

 33 p on file at Northwest and Alaska Fish. Cent.. Auke Bay 

 Lab., Natl. Mar Fish. Serv., NOAA, PO. Box 155, Auke Bay. AK 

 99821). 



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