What concentration of estrogen caused population decline in fathead minnows?
Whole-lake experiments with the synthetic estrogen 17alpha-ethinylestradiol exposed fathead minnows to approximately 5–6 nanograms per litre and documented feminisation, reproductive failure, and a severe population decline. The result is ecologically important because nanogram concentrations can occur downstream of wastewater inputs. Endocrine pathways operate through high-affinity receptors, so a low mass concentration need not imply a weak biological response. Community-level consequences can emerge when physiological injury changes survival, reproduction, species interactions, or the flow
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
