Importance of Laboratory-Derived Metal Toxicity Results in Predicting In-Stream Response of Resident Salmonids

Abstract

Acute toxicity and maximum acceptable toxicant concentration (MATC) values, derived under laboratory conditions, provide useful and valid means for predicting environmental impacts of metals on trout populations in natural environments. Toxicity results from in situ bioassays, using unacclimated (hatchery-reared) rainbow trout and other resident salmonids, agree closely with laboratory-derived toxicity findings where fish species, fish size, and water hardness are similar. Concentrations of zinc, copper, and cadmium increase from trace levels in the Slate River, in Colorado, above the confluence with the metal-mine drainage of Coal Creek, to amounts in excess of those concentrations found to be acutely toxic to unacclimated rainbow trout under laboratory experimentation. Resident brown and brook trout were severely impacted by the metals introduced by Coal Creek. Acute toxicity occurred during the August in situ bioassay at the Slate River station immediately below Coal Creek. Stations farther downstream, where the concentrations of metals decreased to MATC levels for brook trout, showed a marked reduction in the number of resident salmonids and probable restrictions in upstream spawning migrations.

Acclimation-Induced Changes in the Toxicity of Zinc and Cadmium to Rainbow Trout

“…Knowledge of the fate and bioavailability of the materials involved in these studies does not readily explain the differences noted between laboratory toxicity test results and field observations. Furthermore, recent studies present evidence to indicate that natural populations of aquatic organisms have the ability to acclimate to metals such as Zn [1][2][3][4], Cd [1][2][3], Cu [2], and Hg [5], as well as to organic contaminants such as phenol [6] and several pesticides [7][8][9].…”

“…Toxic responses of several fish species to sublethal chemical concentrations used in the laboratory have changed after prior exposure to sublethal chemical concentrations. Such changes have been recognized for Zn [2,[10][11][12][13][14], Cd [4,[15][16][17], Cu [18][19][20], As [21], Al [22], Cl [23], and synthetic detergents [24]. The majority of these studies were not designed to study changes in acclimation directly; rather, acclimation was reported as a secondary observation, usually in terms of changes in timeto-death of exposed organisms.…”

Acclimation‐induced changes in the toxicity of zinc and cadmium to rainbow trout

“…Knowledge of the fate and bioavailability of the materials involved in these studies does not readily explain the differences noted between laboratory toxicity test results and field observations. Furthermore, recent studies present evidence to indicate that natural populations of aquatic organisms have the ability to acclimate to metals such as Zn [1–4], Cd [1–3], Cu [2], and Hg [5], as well as to organic contaminants such as phenol [6] and several pesticides [7–9].…”

“…Toxic responses of several fish species to sublethal chemical concentrations used in the laboratory have changed after prior exposure to sublethal chemical concentrations. Such changes have been recognized for Zn [2,10–14], Cd [4,15–17], Cu [18–20], As [21], Al [22], Cl [23], and synthetic detergents [24]. The majority of these studies were not designed to study changes in acclimation directly; rather, acclimation was reported as a secondary observation, usually in terms of changes in time‐to‐death of exposed organisms.…”

Toxicity of cadmium to early life stages of brown trout (Salmo trutta) at multiple water hardnesses

“…Cadmium is commonly found as a contaminant in the Colorado mineral belt and often is associated with waters affected by historic mining activities. Brown trout (Salmo trutta) are an important component of Colorado ecosystems in many headwater streams, but their densities often are reduced because of metal contamination [2]. Limited cadmium toxicity data indicate that brown trout is perhaps the most acutely sensitive aquatic species tested [3].…”