Plasma ionic composition of the Atlantic salmon ( Salmo salar ), white sucker ( Catostomus commersoni ), and alewife ( Alosa pseudoharengus ) in some acidic rivers of Nova Scotia

• Published in: Canadian Journal of Zoology
• Main Author: Lacroix, Gilles L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1985
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1139/z85-334; http://www.nrcresearchpress.com/doi/pdf/10.1139/z85-334

Atlantic salmon (Salmo salar) smolts migrating from two acidic rivers (pH 4.9 and 5.2) had high hematocrit levels (> 50%) and low plasma [Cl − ] (< 100mequiv. L −1 ). The hematocrit level was 10% higher and plasma [Na + ] was 17% lower in smolts of the more acidic of the two rivers. Salmon parr in rivers of mean pH 5.0, 5.4, and 6.0 over a 7-month period had high hematocrit levels (> 40%) and low plasma [Cl − ] (< 125 mequiv. L −1 ). Plasma [Na + ] and [Cl] were both slightly less (~ 5%) and plasma [K + ] was higher (> 1.5 times) in parr from the river of pH 5.0 than in those from the other two rivers. Atlantic salmon smolts were more sensitive to low pH (plasma [Na + ] 14% less, [Cl] 17% less, and hematocrit level 37% higher) than parr, and parr of the 0+ age-class were more sensitive (plasma [Na + ] 9% less) than 1+ parr. Prespawning white suckers (Catostomus commersoni) and alewives (Alosa pseudoharengus) migrating in a river at pH 4.9 had high hematocrit levels and low plasma [Cl − ], and alewives (hematocrit, 66%; plasma [Cl], 65 mequiv. L −1 ) were more severely affected than suckers (hematocrit, 42%; plasma [Cl − ], 91 mequiv. L −1 ). Plasma [Ca 2+ ] in females of both species was not greatly elevated relative to males (female/male [Ca 2+ ] = 1.21 in suckers and 1.14 in alewives), suggesting a possible impairment of calcium metabolism associated with ovarian development. The physiological effects observed in fish inhabiting soft waters (external [Ca 2+ ] < 0.10 mequiv. L −1 ) at pH levels of about 5.0 generally correlated well with the laboratory "models" of acid exposure in soft water.