Abstract
Trace metal contamination in the aquatic ecosystem occurs worldwide: although copper is an essential trace metal, it is considered as a pollutant at certain levels in China. Freshwater crayfish Cambaroides dauricus is a commercially important wild species in northeastern China, in which is an important heavy industry area. The population of C. dauricus was decreasing sharply due to the environmental pollution and human intervention over the past 20 years. However, nothing is known regarding the responses of this species to trace metal toxicants. This study aimed to determine the acute and chronic toxicity of Cu and its toxicological effects on respiratory metabolism, as well as Cu accumulation in C. dauricus. The acute (96 h) median lethal concentration (LC50) value of 32.5 mg/L was detected in C. dauricus. Then, acute (96 h; 8.24, 16.48 mg/L) and sub-chronic (14 days; 2.06, 4.12 mg/L) exposure in Cu was investigated by estimating the oxygen consumption rate, ammonium excretion rate, and Cu accumulation. Both acute and sub-chronic Cu exposure induced an inhibition of the oxygen consumption rate and ammonium excretion rate, and thereby, an increased O:N ratio. The shift in O:N ratio indicated a metabolic substrate shift towards lipid and carbohydrate metabolism under Cu stress. Cu accumulation in the hepatopancreas and muscles throughout the study was found to be time-dependent and concentration-dependent. The maximum accumulation in the hepatopancreas and muscle were almost 31.6 folds of the control after 14 days’ exposure to 4.12 mg/L concentration. Based on the present work, we suggest that crayfish be considered a potential bioindicator of environmental pollution in freshwater systems. The study provides basic information for further understanding of the toxicological responses of this species to trace metals.
Highlights
Trace metal contamination in the aquatic ecosystem occurs worldwide: copper is an essential trace metal, it is considered as a pollutant at certain levels in China
Trace metal contamination in aquatic ecosystems has begun to grow at an alarming rate and constitutes a significant global problem[1]
As shown in the Report on the State of the Ecology and Environment in C hina[2] and the Environmental quality bulletin of China’s coastal waters[3], the high concentration trace metal pollution have been reported in coastal waters, rivers and estuaries, even in the underground water, due to the directly discharged industrial pollution sources, domestic pollution sources and comprehensive drain outlets
Summary
Trace metal contamination in the aquatic ecosystem occurs worldwide: copper is an essential trace metal, it is considered as a pollutant at certain levels in China. Freshwater crayfish Cambaroides dauricus is a commercially important wild species in northeastern China, in which is an important heavy industry area. This study aimed to determine the acute and chronic toxicity of Cu and its toxicological effects on respiratory metabolism, as well as Cu accumulation in C. dauricus. As shown in the Report on the State of the Ecology and Environment in C hina[2] and the Environmental quality bulletin of China’s coastal waters[3], the high concentration trace metal pollution have been reported in coastal waters, rivers and estuaries, even in the underground water, due to the directly discharged industrial pollution sources, domestic pollution sources and comprehensive drain outlets. The northeastern China is an important heavy industry area, the serious water pollution, especially of heavy metal pollution, has resulted in the population of C. dauricus decreasing significantly to endangered species over the past 20 years. As far as we know, no research has been examined the effects of trace metals on this species
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