Effects of water-borne copper and lead on metabolic and excretion rate of bahaii loach (Turcinoemacheilus bahaii)

Beyond the role of anthropogenic activities, natural sources of metal contaminations are still controversial, together counting, however, as a major threat to inland and coastal waters, becoming an even more prominent stressor for aquatic life. To address the effects of metals on the physiological response of fish, standard metabolic rate (SMR), maximum metabolic rate (MMR), aerobic scope (AS) and factorial aerobic scope (FAS) as well as specific rate of ammonia excretion (Jamm) of Turcinoemacheilus bahaii were determined following different water-borne Cu2+ and Pb2+ treatments. Following LC50-96 h determination, 72 fish (BW = 1.153 ± 0.56 g and TL = 6.155 ± 0.97 cm) were exposed to different amounts of Cu2+ and Pb2+ in 9 different treatments (eight fish/treatment), including 0.910 mg l−1 Cu2+ for 24 h, 0.455 mg l−1 Cu2+ for 7d, 0.182 mg l−1 Cu2+ for 14d and 0.091 mg l−1 Cu2+ for 30 d as well as 124.430 mg l−1 Pb2+ for 24 h, 62.215 mg l−1 Pb2+ for 7d,12.443 mg l−1 Pb2+ for 14d, 6.221 mg l−1 Pb2+ for 30d and control. The SMR of fish was reduced following exposures to all Cu2+ and Pb2+ treatments (P < 0.05), except for 30d exposure as compared with the control. The MMR remained steady following all Cu2+ treatments while it was raised significantly (P < 0.05) following Pb2+ treatments at 7, 14 and 30d exposure. Although the AS showed a similar pattern to MMR, the FAS was elevated (P < 0.05) following all the treatments when compared with control. Lower Jamm were observed following all metals-treated fish in comparison with control (P < 0.05). In addition, higher (P < 0.05) levels of injuries were observed following all Cu2+ and Pb2+ treatments in gills and kidneys. The results suggest that Cu2+ and Pb2+ over the experimental period could impair the metabolic and excretory capacities, hence affecting the possible physiological performance of fish.