First observation of intersex cyprinids in the Po River (Italy)

Barbel (Barbus plebejus, Cyprinidae) were captured in the Po River, upstrea m and downstream from the confluence of the Lambro River, a polluted tribut ary of the major Italian watercourse. The gonads of the two groups of barbe l have been histologically examined, and only the downstream specimens show ed histo-morphological alterations that can be related to the Lambro tribut ary as a source to the main river of endocrine disrupting chemicals, possib ly with estrogenic effects. In fact, 50% of the barbel captured (8 of 16 fi sh) in the downstream reach showed intersex gonads. (C) 2001 Elsevier Scien ce B.V. All rights reserved.