Effects of environmental pH and calcium on ammonia toxicity in channel catfish

Transactions of the American Fisheries Society
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Abstract

The twenty-four-hour median lethal concentrations (24-hour LC50) of total ammonia nitrogen (TA-N) to channel catfish (Ictalurus punctatus) at pH 7, 8, and 9 (total hardness, 40 mg/liter; temperature, 21–25 C) were 263.6 ± 11.3 (SE), 38.8 ± 1.8, and 4.5 ± 0.2 mg/liter, respectively. The 24-hour LC50 of un-ionized ammonia nitrogen (UIA-N) concentration at pH 8 was significantly higher (1.82 ± 0.06 mg/liter) than at pH 7 or 9 (1.39 ± 0.06 and 1.49 ± 0.12 mg/liter). Enrichment of the water to 440 mg/liter total hardness at pH 7 significantly increased the 24-hour LC50 of TA-N and UIA-N (356.3 ± 16.4 and 1.79 ± 0.07). Fish exposed to 25 mg/liter TA-N for 12 hours at pH 7 and 8 showed no differences from control fish in hematocrit, percent total plasma protein, or plasma and muscle chloride. Plasma sodium showed no difference between control and experimental groups at pH 7; however, a significant decrease occurred in fish exposed to 25 mg/liter TA-N at pH 8. No differences in blood pH were found between the control groups and fish exposed to 100 and 200 mg/liter TA-N at pH 7, and to 10 and 25 mg/liter TA-N at pH 8. Plasma sodium depletion is suggested as a contributing mechanism of ammonia toxicity.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effects of environmental pH and calcium on ammonia toxicity in channel catfish
Series title Transactions of the American Fisheries Society
DOI 10.1577/1548-8659(1980)109<229:EOEPAC>2.0.CO;2
Volume 109
Issue 2
Year Published 1980
Language English
Publisher Taylor & Francis
Publisher location Philadelphia, PA
Contributing office(s) Leetown Science Center
Description 6 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Transactions of the American Fisheries Society
First page 229
Last page 234