Typology of aquatic habitats in the great ouse, a small regulated lowland river

Abstract

AbstractA study of aquatic habitat types was undertaken in August 1989 on the River Great Ouse. Habitat character at 44 sites was evaluated via twelve qualitative and quantitative environmental variables. Discriminant Analysis of the environmental data revealed a weak discrimination of sites corresponding with longitudinal changes in channel width. Distinction between the habitat types in the analysis was relatively weak. Compared with unregulated European lowland rivers of similar geomorphological origin, the Great Ouse possesses little transversal habitat diversity (abandoned channels, oxbows, etc.) and the ponding effect of water retention structures in downstream sections appears to have created a slight longitudinal gradient in channel width and depth. This comparatively low habitat heterogeneity corroborates a previous report of limited recruitment in the Great Ouse by 0 + fishes of both limnophilous and rheophilous reproductive guilds, with a predominance of generalist spawners.