Cottus rhenanus density (number of individuals 300 m⁻²) in relation to abundance of six sediment types (A-F) in transects, in relation to the percentage area of large structures and riffles in a transect (G-H), and the mean transect depth (I). p-values indicate significance of a relation, determined using negative binomial GLM's. Significant relations were determined between C. rhenanus density and (F) a relatively high abundance of boulders (> 200 mm), (H) large structures (woody debris), and (I) the mean depth of a transect. The solid lines represent the predicted values with corresponding 95% confidence intervals (shown with dashed lines), predicted by the models of a significant relationship.