Histochemical and biochemical markers in trout larvae exposed to river sediments

Rainbow trout larvae (Oncorhynchus mykiss) were exposed to bottom sediments collected from 4 sites of the River Po, located close to the springs (UP) of the main Italian river and downstream the confluence of 3 tributaries of its middle reach, the Rivers Ticino (TI), Adda (AD) and Lambro (LA), which drain areas characterized by increasing anthropogenic stress. After 7 days of exposure the trout larvae were examined for both biochemical and histochemical markers and results indicate the presence of a toxicological risk for the fish community of the AD- and particularly LA-downstream stretches. The reach of the River Po receiving the Ticino River was confirmed to be less hazardous in conjunction with the UP area.