Estrogenic effects of octylphenol on carp (<I>Cyprinus carpio</I>)

Abstract

The aim of the study was to investigate the estrogenic effects of octylphenol (OP) on carp (Cyprinus carpio). Vitellogenin (Vtg) and the parameters of growth and development were determined as biomarkers. The one-year-old carp from a large reservoir were kept in the laboratory for 7 days. Then they were exposed to OP under semi-static conditions for 32 days. They were fed once a day. The water temperature was (18±1) ℃ during the experiment. Five concentrations of OP at 10,50,100,300 and 500 μg/L were selected for this study. The mortality,abnormal behavior and appearance of the carp were recorded during the exposure. At the end of the exposure,fish were sampled to measure body weight,body length and gonadal weight,then plasma and liver homogenates were prepared for the determination of Vtg concentration by ELISA. The data were analysed with SPSS 11.5. At the end of exposure,it was found that there was no significant difference in the survival and growth of the fish. The exposure to OP caused obvious changes in gonadosomatic index (GSI). In accordance with the increase of the OP concentration,the GSIs of female carp increased,while that of male carp decreased. OP at 10 μg/L caused the GSIs of male carp decreased significantly (P0.05). The GSIs of female carp increased significantly when the OP concentration reached 50 μg/L (P0.05). OP induced the synthesis of Vtg in male carp. Vtg was not detected in plasma or liver homogenates in control groups,and it was detected in some of the samples in 10 μg/L group. The Vtg levels increased greatly when the OP concentration reached 50 μg/L (P0.05). The Vtg levels in 500 μg/L group were significantly lower than those in 300 μg/L (P0.01),but significantly higher than those in 100 μg/L group (P0.01). The results indicated that octylphenol (OP) has obvious impact on the gonadal development of carps. It can induce Vtg synthesis in male carps. OP has visible estrogenic effects on carp (Cyprinus carpio) although it did not affect the growth of the fish at low exposure concentrations.