US EPA

2771447 

Journal Article 

Reproductive effects of estrogenic and antiestrogenic chemicals on sheepshead minnow (Cyprinodon variegatus) 

Brouwer, M 

1999 

Accumulating scientific data has shown that many synthetic chemicals can adversely affect the endocrine system of humans and wildlife. Some of these compounds have estrogenic or antiestrogenic effects. In this study, adult lab-reared male Sheepshead minnows (Cyprinodon variegates) were exposed to estrogenic 4-tert-octylphenol and females to antiestrogenic cadmium in aquaria to examine: (1) vitellogenin in male blood as sign of feminization, (2) F0 generation fecundity/fertility, (3) embryonic development/egg hatching/survival rate of F1 generation fry, and (4) effects on gonads. Histology showed increased testis anomalies and decreased later-stage sperm development (spermatozoa) with increasing OP exposure. No effects on embryo development/survival rate were observed. Breeding groups composed of control males and cadmium- exposed females behaved normally. However, groups composed of male fish exposed to the highest OP concentration and females exposed to the highest cadmium concentration failed to produce any eggs. 

Cyprinodon variegatus; Endocrinology; Vitellogenesis; Pollution effects; Sex hormones; Freshwater; Animal reproductive organs; Brackish