The importance of site selection in monitoring the macroinvertebrate communities of the Yarra River, Victoria.

The condition of the macroinvertebrate fauna of the Yarra River deteriorates progressively downstream from the virtually pristine headwater areas, through cleared rural areas in the mid-Yarra, to urban areas in the lower sections of the Yarra. It was found during a four year study, that the physico-chemical parameters affecting the fauna varied substantially in relation to the different physical characteristics of each site. In general, it is suggested that nutrients and the riparian vegetation had greatest impact on the riffle communities, and turbidities had greatest impact on the pool communities. The physical characteristics of each site also influenced the type and degree of response in the fauna to fluctuations in flow. Full consideration should therefore be given to the type of stream habitat sampled when attempting to determine which water quality parameters have significant long-term effects on the condition of the fauna.