Gill morphology of native brown trout Salmo trutta m. fario experiencing acute and chronic acidification of a brook in Bavaria FRG

Gill morphology of brown trout Salmo h t t a m.fano inhabiting a periodically acidified brook in the eastern part of Bavaria, Federal Republic of Germany, was studed by light and electron microscope.Gills from brown trout caught at a snowmelt period (pH 4.9; A1 0.8 mg I-') were characterized by an increase in mucous cells and excessive mucus production w h c h caused the fusion of secondary lamellae.Gills from brown trout sampled from the same brook in a dry period in September (pH 6.2 to 6.5; A1 0.1 mg I-') showed an increase in chloride cells In the secondary lamellar epithelium and an attachment of opposing cells, epithelia1 or chloride cells in the respiratory epithelium of neighbouring secondary lamellae.