First observation of intersex cyprinids in the Po River žItaly/

Barbel ŽBarbus plebejus, Cyprinidae. were captured in the Po River, upstream and downstream from the confluence of the Lambro River, a polluted tributary of the major Italian watercourse. The gonads of the two groups of barbel have been histologically examined, and only the downstream specimens showed histo-morphological alterations that can be related to the Lambro tributary as a source to the main river of endocrine disrupting chemicals, possibly with estrogenic effects. In fact, 50% of the barbel captured Ž8 of 16 fish. in the downstream reach showed intersex gonads.