Effect of Nitrite on the Embryonic Development of Atlantic Salmon (Salmo salar)

Effects of nitrite on eggs, alevins, and fry of Atlantic salmon (Salmo salar) were studied and of these developmental stages eggs were the most resistant with a 24-h LC 50 value of 3276 mg∙L −1 N∙NO 2 . Upon hatching tolerance sharply decreased, the 24-h LC 50 value for early alevins (2940 mg∙L −1 N∙NO 2 ) decreasing to 121.8 mg∙L −1 N∙NO 2 . Development in freshwater or dilute saline (10 mmol∙L −1 NaCl) proceeded normally without mortalities. Long-term exposure to nitrite concentrations as low as 14 mg∙L −1 N∙NO 2 delayed hatching and retarded embryo growth and development as well as producing cardiovascular effects such as a reduced heart rate. The physiological and environmental implications of nitrite exposure are discussed.