Effects of sewage effluents on some reproductive parameters in adult Zebra fish (Danio rerio)

Sewage treatment plants are sources of anthropogenic substances in the environment. Sewage effluents elicit adverse effects on the reproductive abilities of aquatic organisms. The aim of the project was to assess the efficiency of the treatment processes at a sewage treatment plant in Sweden with zebra fish as test models for aquatic organisms. The project entailed the exposure of adult male and female zebra fish to the sewage effluents (A1- A7) for 21 days. The reproductive parameters monitored were spawning ability, fertilization, fecundity and vitellogenin concentration. Fish exposed to effluent A2 (after sedimentation treatment) had a higher number of successful spawning compared to the controls (A1 and A8). Fish in groups A3 (outlet L1), A4 (biofilter) and A5 (ozone) exhibited a decrease in spawning ability. Adult female fish exposed to effluent A4 exhibited low fecundity compared to the controls. The processes at the sewage treatment plant need to be optimized to forestall adverse effects on the reproductive abilities of aquatic organisms.