What group of pollutants has contributed to sex ratio shifts in fish?
Estrogens, including natural hormones and synthetic pharmaceutical analogues, can shift fish sex ratios by altering endocrine signalling during sensitive developmental periods. Exposure may induce vitellogenin in males, create intersex gonads, feminise genetic males, reduce sperm quality, and lower reproductive success. Fertilisers chiefly alter nutrient status, while heavy metals and chlorinated hydrocarbons have other toxic actions, although some compounds in those groups can also disrupt endocrine systems. Aquatic effects depend on chemical form, persistence, solubility, dose, and the capac
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology