Assessment of river health in Australia by diatom assemblages - A review

Abstract

This paper summarises the findings of two national projects carried out by the author, covering the largest area ever investigated on the use of diatoms for monitoring river health in Australia, as well as to recommend future directions in diatom river monitoring in Australia. The first project (1995 to 1998) involved South-west Western Australia - well known for its forests and abundance of streams and rivers. Data on environmental variables and diatom taxa were obtained from 136 sites, out of which 117 were used as reference sites and 29 as monitoring (impacted) sites. Some 20 sites were randomly selected from the reference sites and used as 'test sites' to verify internal consistency of the reference sites which were considered to be relatively pristine. The streams and rivers were finally classified into four distinct groups based upon environmental factors and diatom distribution pattern. The second project involved monitoring the health of urban streams around the city of Perth, western Australia. The investigation (1996 to 1999) focussed on classification of the urban streams based on water quality parameters and 'stream conditions' and development of a predictive model using diatoms as biomonitors. Close to 180 sites were sampled with 30 environmental variables measured. All the sites were classified on the basis of seven environmental variables with the highest correlation coefficient with the sites, using the multivariate pattern analysis program PATN. The reference and monitoring sites were mostly separated on the basis of environmental factors and distinct diatom assemblages. Currently, a national protocol for assessing the health of all rivers using diatoms in Australia is being compiled.