Tissue-specific Cu bioaccumulation patterns and differences in sensitivity to waterborne Cu in three freshwater fish: rainbow trout ( Oncorhynchus mykiss), common carp ( Cyprinus carpio), and gibel carp ( Carassius auratus gibelio)

Abstract

Rainbow trout ( Oncorhynchus mykiss), common carp ( Cyprinus carpio) and gibel carp ( Carassius auratus gibelio) were exposed to copper (1–20 μM) in softened Antwerp City tap water at pH 7.3 ± 0.1 and with a water hardness of 292.4 ± 8.1 mg/L CaCO 3 (Ca 100.8 ± 3.0 mg/L; Mg 11.0 ± 0.2 mg/L). LC50s (96 h) were determined and copper accumulation in gills, liver, and kidney assessed over a 10-day period. Rainbow trout (96 h LC50: 3.3 μM/210 μg/L) were three times more sensitive to Cu exposure than common carp (96 h LC50: 10.4 μM/661 μg/L) and almost seven times more sensitive than gibel carp (96 h LC50: 22.0 μM/1398 μg/L). After 96 h, the incipient lethal level (ILL) was reached for common carp, and by the end of the experiment (>120 h) also for rainbow trout. The ILL was never reached for gibel carp. Survival analysis confirmed the differences in sensitivity shown by the 96 h LC50 values. At 1 μM Cu, the relative risk to die was six to seven times greater for rainbow trout as for common or gibel carp, respectively, while it was 9000 and 19,000 times greater at 5 μM Cu. Only the environmental Cu concentrations contributed significantly ( P < 0.001) to the Time-To-Death (TTD). Tissue Cu concentrations did not relate to TTD. Among species, a clear difference in metal handling was apparent, with high liver residues and liver accumulation rates for the most sensitive species, the rainbow trout, and lower liver but higher kidney residues and kidney accumulation rates for the most resistant species, the gibel carp. Gill concentrations and accumulation rates were lowest in the sensitive rainbow trout.