RESUMEN
At present volumetric activity of ß-emitting radionuclides in water at various locations of the Techa River ranges from 5 to 40-Bq/L; a specific activity of ß-emitting radionuclides in the bottom sediments at various locations ranges 10 Ito 106 Bq/kg dry weight. A significant increase of the erythroblast content in blood as compared to that in the roach from the reference watercourse (the Miass River) was observed during spawning in the spring. Due to this fact the number of erythrocytes was equal to that in the control animals under chronic radiation exposure at the dose rates of 0.9 and 16 µGy/day, and was insufficient at the dose rate of 108 gGy/day. During summer feeding no changes in the indexes of erythropoiesis in roach were observed under chronic radiation exposure at the dose rate of 0.9 µGy/day; the number of erythrocytes in the peripheral blood declines when the dose rates are 16 and 108 µGy/day. When performing a regression analysis, we revealed a dose-rate-dependent decrease in the absolute number of erythrocytes, normocytes, polychromatocytes, dividing and non-dividing erythroid cells in the peripheral blood of roach from the Techa River and an increase of a relative number of normochromatophylic erythrocytes.