Impact of catchment land use on bacterial communities within stream biofilms

The bacterial community structure in epilithic biofilms within 18 different streams was characterised using a community DNA fingerprinting technique (automated ribosomal intergenic spacer analysis—ARISA). Each stream has previously been described in terms of the dominant catchment land use, relative level of human disturbance and using a broad suite of water quality variables. Combination of ARISA with multivariate statistical analysis and ordination revealed that bacterial communities in streams located within rural catchments were significantly different to those within urban catchments. Broad-scale catchment land use described the largest component of the observed variation with no single water quality variable found to be a dominant determinant of the observed bacterial community variability, assessed using distance based redundancy analysis (dbRDA) of the ARISA data. This study highlights the potential of bacterial ARISA to provide a rapid and cost-effective approach to monitor the impact of catchment land use on aquatic ecosystems, such as the influence of encroaching urban development on the ecological health of rural streams.