Acute waterborne nickel toxicity in the rainbow trout (Oncorhynchus mykiss) occurs by a respiratory rather than ionoregulatory mechanism

E. F. Pane, J. G. Richards, C. M. Wood

Research output: Contribution to journalArticlepeer-review

107 Scopus citations


The acute mechanism of toxicity of waterborne nickel (Ni) was investigated in the rainbow trout (Oncorhynchus mykiss) in moderately hard (∼140 mg l-1 as CaCO3) Lake Ontario water, where the 96-h LC50 for juvenile trout (1.5-3.5 g) was 15.3 mg (12.7-19.0, 95% C.L.) dissolved Ni l-1. No marked impact of Ni exposure on average unidirectional or net fluxes of Na+, Cl-, or Ca2+ was observed in juvenile trout exposed for 48-60 h to 15.6 mg Ni l-1 as NiSO4. Furthermore, when adult rainbow trout (200-340 g) were fitted with indwelling dorsal aortic catheters and exposed for 117 h to 11.6 mg Ni l-1 as NiSO4, plasma ions (Na+, Cl-, Ca2+, and Mg2+) were all well conserved. However, mean arterial oxygen tension dropped gradually to ∼35% of control values. This drop in PaO2 was accompanied by an acidosis primarily of respiratory origin. PaCO2 rose to more than double control values with a concomitant drop in arterial pH of 0.15 units. Acute respiratory toxicity was further evidenced by a significant increase in hematocrit (Ht), and plasma lactate, and a significant decrease in spleen hemoglobin (Hb). Following 117 h of exposure to 11.6 mg Ni l-1, the gill, intestine, plasma, kidney, stomach, and heart accumulated Ni significantly, with increases of 60, 34, 28, 11, 8, and 3-fold, respectively. Brain, white muscle, liver, and bile did not significantly accumulate Ni. Plasma Ni exhibited a remarkable linear increase with time to levels approximately 30-fold higher than controls. We conclude that in contrast to most other metals, Ni is primarily a respiratory, rather than an ionoregulatory, toxicant at exposure levels close to the 96-h LC50. The implications of a waterborne metal as an acute respiratory toxicant (as opposed to ionoregulatory toxicants such as Cu, Ag, Cd, or Zn) with respect to toxicity modeling are discussed.

Original languageEnglish (US)
Pages (from-to)65-82
Number of pages18
JournalAquatic Toxicology
Issue number1
StatePublished - Mar 17 2003


  • Ionoregulation
  • Nickel
  • Rainbow trout
  • Respiratory toxicity
  • Waterborne

ASJC Scopus subject areas

  • Aquatic Science


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