The effect of dissolved oxygen and salinity on the toxicity of ammonia to smolts of salmon, Salmo salar L.

Abstract

The survival of Atlantic salmon srnolts on exposure to constant concentrations of ammonia has been measured under laboratory conditions. At concentrations of dissolved oxygen close to the air-saturation value, the 24-h LC50 of un-ionised ammonia is 0.15 mg NH, 1 -I in fresh water (hardness 264 mg I-' as CaCO,) and 0.3 mg NH,I-l in 30% sea water; at concentrations of dissolved oxygen of 3.5 mg 1-i in fresh water and 3.1 mg 1 -I in 30% sea water, the 24-h LC50 is 0.09 mg NH, 1-1 and 0.12 mg NH, 1-1 respectively; for fish acclimated for 1 day to a concentration of ammonia close to the 24-h median for un-acclimated fish, the median is increased between 38 and 79%, depending on test conditions.

Nitrogen pollution in mariculture: toxicity and excretion of nitrogenous compounds by marine fish

“…Ammonia is acutely toxic between 0.09 and 3.35 mg 1-1 as NH3-N in seawater for the few species that have been investigated (Table 1). Toxicity is also dependent on salinity, temperature, and water pH (Hazel et al, 1971;Alabaster et al, 1979Alabaster et al, , 1983Alderson, 1979;Miller et al, 1990;Soderberg and Meade, 1991;Wajsbrot et al, 1991).…”

“…Alabaster et al (1979) reported 24 h LCs0 for Atlantic salmon of 0.09 and 0.23 mg 1 -I NH3-N at DO levels of 3.1 and 9.5 mg 1-1 respectively; thus the risk of ammonia toxicity may be minimized with DO > 10 mg 1-1 in seawater. Ammonia toxicity is ameliorated at acidic pH values in freshwater (Russo and Thurston, 1991), but the pH effect in seawater is unclear.…”

“…Thus it is difficult to suggest a suitable pH to protect cultured fish from ammonia toxicity in seawater at present. Fullstrength seawater is preferable to brackish water because increased salinity (and ionic strength) appears to reduce toxicity (Hazel et al, 1971;Alabaster et al, 1979;Soderberg and Meade, 1991).…”

A Combined Water Management Approach Based on River Water Quality Standards

“…Alabaster et al, 1979;Hamm, 1991;Haywood, 1983;Hvitved-Jacobsen, 1982;Jacob et al, 1984;Russo & Thurston, 1977) were taken into account additionally. The data stock was completed by our investigations (Podraza et al, 2002) with fry released into the water upstream and downstream of the discharge points.…”

Assessment of Dredged Material Toxicity in San Francisco Bay

“…The percent of total ammonia present in the unionized form is significantly affected by factors such as pH, temperature, and to a lesser degree the ionic strength of the solution (e.g. hardness or salinity) (Thurston et al 1981b, Alabaster et al 1979, Emerson et al 1975, Whitfield 1974, Skarheim 1973.…”