How copper excess influences homeostasis of the bank vole (Myodes glareolus)

Copper is a physiologically occurring trace element, the availability of which to wild small mammals is constantly increasing. This research deals with the questions of how copper in doses equivalent to those found in the natural environment from polluted areas (Cu I – 150 mg kg-1, Cu II – 600 mg kg-1) influences homeostasis of small rodents. The following were used as indicators: ratios of organs to body mass, blood parameters (haematocrit, haemoglobin), copper, iron and zinc concentrations in selected tissues and in excrements. The bank vole was used as a model species (n = 72). Haematocrit was assessed using a haematocrit reader, while haemoglobin was determined with a spectrophotometer. The content of Cu, Fe and Zn was analyzed using the flame method. Ratios of the liver and kidneys to body mass were significantly lower in animals exposed to 600 mg kg-1 Cu than in the control. Copper accumulated in the liver, kidneys, brain and excrements of the Cu II animals of both sexes. It also influenced the iron and zinc homeostasis by decreasing the iron concentration in the kidneys of both sexes, in the liver of females and in male testes. Additionally, it caused a decline in iron excretion in females. Compared to the control, the zinc concentration was significantly higher in the liver and brain of animals exposed to copper solutions as well as in the kidneys of copper treated males. Along with an increase in copper, the zinc concentration in faeces decreased significantly. In conclusion, copper pollution influences negatively the homeostasis of small mammals. Consequently it may interfere with trophic chains, which could affect adversely the degree of biodiversity.