COPPER CONTRIBUTES TO THE AMPHIBIAN DECLINE

Although copper is an essential micronutrient normally subject to effective homeostatic control, excess dietary intakes can in some circumstances be toxic. Many of the toxic effects of copper, such as increased lipid peroxidation in cell membranes and DNA damage, are related to its role in the generation of oxygen free radicals. Both Cu deficiency and toxicity can occur in natural conditions and may lead to diminished animal reproduction,1 various organs dysfunctions,2 development of pathological lesions and, ultimately, to death.3 Copper can be released into the environment by both natural sources and human activities and it is very widespread in the environment. Aquatic environment is a concentrator for this metal. Soluble copper compounds is one of the most toxic metals to aquatic organisms and ecosystems.4 Our aim is to study the effects of copper accumulation in aquatic organisms. We have utilized adult Xenopus laevis and a concentration of 1mg/L of CuCl for 3 weeks which is the lower concentration required in the daily human diet. In aquatic environment the concentration of copper reaches higher values. Our preliminary data showed that, in treated Xenopus, the erythrocytes were smaller in size but more numerous. These data support the hypothesis of a possible microcytic anemia, whose symptoms are not just smaller size of the erythrocytes, but also their greater number to compensate the transport of oxygen. Moreover the dorsal skin showed morphological changes such as: erosion of the stratum corneum, disorder of the various layers that form the epidermis, increase in melanocytes and emptying of the mucous glands cells. Our data show that the Cu causes suffering in treated Xenopus suggesting that it is one of the pollutants involved in the decline of the amphibians.