Christopher Siva

Diatoms As Indicators of Water Quality in Urban Streams: Urban Pollution Studies in the Swan River Basin, Perth, Western Australia Christopher Siva

The temporal and spatial distribution patterns of diatoms colonising artificial substrates were used to develop a model indicating different levels of degradation in urban streams of the Swan River, Perth, Western Australia. Diatom and algal based matrices were used to develop a multimetric index used to categorise the environmental condition of stream sites into four urban groups: (1) Streams in forested catchments with good to excellent ecological integrity and > lOkm from the estuary (2) Streams receiving estuarine water with partial stream degradation (3) Streams in proximity to agricultural land with moderate to severe stream degradation and 5-1Okm from the estuary (4) Streams in proximity to industrial sites with moderate to severe stream degradation and < 5km from the estuary Diatom and Cyanobacterial indicator species sampled from artificial substrates have been found to be useful for the assessment of stream conditions in Perth, Western Australia. This index provides environmental managers with a powerful tool to recommend remediation measures to rehabilitate natural streams impacted by urban pollution.