Influence of Water Hardness, pH, and Alkalinity on the Mechanisms of Copper Toxicity in Juvenile Rainbow Trout,Salmo gairdneri

Abstract

Juvenile rainbow trout were exposed to 25–400 μg copper∙L−1 for 24 h. Water hardness, pH, and alkalinity were varied independently at a constant [Na+]. Net and unidirectional sodium fluxes were measured in hard and soft, low-alkalinity water and in hard, high-alkalinity water at neutral pH and pH 5.0. In low alkalinity water, Na+ uptake (Jin) was inhibited at copper concentrations as low as 25 μg∙L−1, and sodium efflux (Jout) was stimulated above 100 μg∙L−1. High-alkalinity water significantly reduced the effects of copper on Jin and Jout, but there was no significant effect of increasing water hardness. The effects of pH 5.0 and copper were additive from 25 to 100 μg∙L−1, but a pure copper effect was found from 200 to 400 μg∙L−1. Fish died when they had lost about 50–55% of their exchangeable Na+ pool. Water hardness and alkalinity had no effect on the apparent uptake of copper, but copper uptake was reduced by about 50% at pH 5.0.

Acute and Subacute Toxicity of Copper Sulfate Pentahydrate (CuSO45 H2O) in the Guppy (Poecilia reticulata)

“…As the alkalinity of water increases, the concentration of copper ions in solution decreases. Consequently, a therapeutic level of copper in water with high alkalinity would be lethal to fish in water with low alkalinity [15]. In the present study, guppies exposed to a 1/10 concentration of TLm 24h value did not show any severe lesions except for mild curling of gill lamellae, and so that amount or less of copper sulfate may be recommended as a treatment dosage for the guppy.…”

Modelling the effects of copper on soil organisms and processes using the free ion approach: Towards a multi-species toxicity model

“…338 suggested that the underlying mechanism of Cu toxicity is binding of Cu to thiol 373 groups in proteins and consequent damage to their structure (Letelier et al, 2005); this 374 has been noted as a reason for the sensitivity of plant ATPases to Cu (De Vos et al, 375 1991) and thus might also be related to the well-established effects of Cu on the 376 Na + /K + -ATPase in animals (e.g. Lauren and McDonald, 1986)). If Cu initially binds 377 to ATPase carrier proteins or ion pumps on the cell membrane, this may account forthe apparent similarity in the binding behaviour of the uptake sites in different taxa, 379 particularly because it is recognised that there is a high conservation of the amino acid 380 sequence and crystal structure of known ion pumps such as metazoan Na + /K + -381…”

Integrated physiological response of tilapia, Oreochromis mossambicus, to sublethal copper exposure

“…The advantage of our approach of ion-transport measurement is indicated by the high control net fluxes, as is demonstrated by a study of Dharmamba and Maetz (1972). In contrast, no positive net fluxes were observed in control rainbow trout and brown trout (Lauren and McDonald, 1986;Reader and Morris, 1988;Reid and McDonald, 1988). Generally, only influx and net flux are measured, with net fluxes determined from chances in the ion concentration in the water, whereas efflux is calculated from the difference between net flux and influx (Spry and Wood, 1985;McDonald, 1986, 1987;Reader and Morris, 1988;Reid and McDonald, 1988).…”

“…The inhibitory effect of Cu on the Na influx may be due to the high affinity of Cu for -SH groups of transport enzymes such as N a+ /K + -ATPase (Stagg and Shuttleworth, 1982b;Beckman and Zaugg, 1988). Cu-induced disturbanc es of the Na influx have also been observed in rainbow trout (Lauren and McDonald, 1986;McDonald et al, 1989). Exposure to high concentrations of Cu has been shown to cause histological alterations in the gills (Baker, 1969;Wilson and Taylor, 1993).…”