Physiological effects of chronic copper exposure to rainbow trout (Oncorhynchus mykiss) in hard and soft water: Evaluation of chronic indicators

Abstract

Effects of chronic copper exposure on a suite of indicators were examined: acute toxicity, acclimation, growth, sprint performance, whole‐body electrolytes, tissue residues, and gill copper binding characteristics. Juvenile rainbow trout were exposed for 30 d to waterborne copper in hard water (hardness = 120 mg/L as CaCO3, pH = 8.0, Cu = 20 and 60 μg/L) and soft water (hardness = 20 mg/L as CaCO3, pH = 7.2, Cu = 1 and 2 μg/L). Significant acclimation to the metal occurred only in fish exposed to 60 μg/L, as seen by an approx. twofold increase in 96‐h LC50 (153 vs 91 μg Cu/L). Chronic copper exposure had little or no effect on survival, growth, or swimming performance in either water hardness, nor was there any initial whole‐body electrolyte loss (Na+ and Cl−). The present data suggest that the availability of food (3% wet body weight/day, distributed as three 1% meals) prevented growth inhibition and initial ion losses that usually result from Cu exposure. Elevated metal burdens in the gills and livers of exposed fish were measures of chronic copper exposure but not of effect. Initial gill binding experiments revealed the necessity of using radiolabeled Cu (64Cu) to detect newly accumulated Cu against gill background levels. Using this method, we verified the presence of saturable Cu‐binding sites in the gills of juvenile rainbow trout and were able to make estimates of copper‐binding affinity (log Kgill=Cu) and capacity (Bmax). Furthermore, we showed that both chronic exposure to Cu and to low water calcium had important effects on the Cu‐binding characteristics of the gills.

Pre‐assessment of environmental impact of zinc and copper used in animal nutrition

“…According to the metallo-region concept, adaptation to natural background levels and also to test conditions may influence the sensitivity to metals. Acclimation/adaptation of daphnia magna and rainbow trout was observed for copper (Bossuyt and janssen, 2003a;Taylor et al, 2000).…”

Nutritive metal uptake in teleost fish

“…It is evident from waterborne toxicity studies that the gill can also contribute considerably to copper uptake (Taylor et al, 2000). Studies by Miller et al (1993) and Kamunde et al (2002a) have highlighted the significance of waterborne copper as a potential nutritional source to rainbow trout.…”

Concentrations of Arsenic, Cadmium, Copper, Lead, Selenium, and Zinc in Fish from the Mississippi River Basin, 1995

“…See Table I for station locations. many (including Cu and Zn) are also essential trace elements that do not normally accumulate in environmentally exposed fish to concentrations that represent a threat to higher-level organisms, even in heavily contaminated areas (Schmitt et al, 1993;. Many elements accumulate preferentially in specific organs and tissues (e.g., May and McKinney, 1977;Harrison and Klaverkamp, 1990;Farag et al, 1995;Goldstein et al, 1996;Goldstein and DeWeese, 1999;Taylor et al, 2000) such as liver (Zn, Cu, etc. ), kidney (Cd), bone (Pb), gill (Cu), or muscle (Hg).…”