V. DOBREVA, A. TSEKOV and I. VELCHEVA
Plovdiv University “Paisii Hilendarski”, BG - 4000 Plovidv, Bulgaria
DOBREVA, V., A. TSEKOV and I. VELCHEVA, 2008. Study of the effect of zinc on gill functions of the crucian carp Carassius gibelio Bloch. Bulg. J. Agric. Sci., 14: 182-185
This study presents the results of research on the effect of the growing concentrations of ZnSO4 (0.5, 1.0, 1.5 and 2.0 mg.l-1) on gill functions of the crucian carp Carassius gibelio Bloch. After a ninety-six hour exposure to Zn, it has been observed that fishes from all ZnSO4 concentrations have decreased breathing intensity (lower levels of the oxygen consumed) - 0.089-0.118 mg.g-1 weight per hour (31-48% less), compared to this of the controls - 0.171 mg.g-1 weight per hour. Furthermore, all fishes exposed to Zn show decreased oxygen deficiency resistance when compared to the controls. The mortality rate of the experimental fishes is from 40 to 71.4%, whereas by the controls it is 11.76%. The results obtained show that even the non-lethal concentrations of Zn compounds lead to gill function impairment of the crucian carp and in combination with a decreased amount of oxygen absorbed in water the effect can be lethal.