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Relative sensitivity of bull trout ( Salvelinus confluentus ) and rainbow trout ( Oncorhynchus mykiss ) to acute exposures of cadmium and zinc
Author(s) -
Hansen James A.,
Welsh Paul G.,
Lipton Josh,
Cacela Dave,
Dailey Anne D.
Publication year - 2002
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620210110
Subject(s) - rainbow trout , trout , acute toxicity , cadmium , biology , toxicity , fishery , soft water , toxicology , environmental chemistry , zoology , chemistry , fish <actinopterygii> , organic chemistry
Bull trout ( Salvelinus confluentus ) were recently listed as threatened in the United States under the federal Endangered Species Act. Present and historical habitat of this species includes waterways that have been impacted by metals released from mining and mineral processing activities. We conducted paired bioassays with bull trout and rainbow trout ( Oncorhynchus mykiss ) to examine the relative sensitivity of each species to Cd and Zn independently and as a mixture. A total of 15 pairs of acute toxicity bioassays were completed to evaluate the effects of different water hardness (30 or 90 mg/L as CaCO 3 ), pH (6.5 or 7.5), and temperature (8 or 12°C) on Cd and Zn toxicity. For both species, the acute toxicity of both Cd and Zn was greater than previously observed in laboratory studies. Bull trout were about twice as tolerant of Cd and about 50% more tolerant of Zn than were rainbow trout. Higher hardness and lower pH water produced lower toxicity and slower rates of toxicity in both species. Elevated temperature significantly increased the sensitivity of bull trout to Zn but decreased the sensitivity (not significantly) of rainbow trout to Zn. At a hardness of 30 mg/L, the toxicity values (i.e., median lethal concentration; 120‐h LC50) for both species were lower than the current U.S. national water quality criteria for protection of aquatic life, indicating that current national criteria may not be protective of sensitive salmonids—including the threatened bull trout—in low calcium waters.