Macroinvertebrate fauna and water quality in two irrigation channels in the Shepparton irrigation region, Victoria

A large amount of water is diverted from rivers into irrigation channels in northern Victoria, but little is known of the biological communities of irrigation channels. A preliminary survey of macroinvertebrates and water quality was conducted in two irrigation channels southwest of Shepparton, Victoria. The macroinvertebrate fauna was relatively rich when compared to the surveys in disturbed streams in northern Victoria. Macroinvertebrate population and community structure changed with distance downstream in both channels. Taxa richness and abundance decreased and the community become more depauperate with increasing distance downstream. Similarly, water quality deteriorated with distance downstream in both channels, with EC turbidity, NO2-N, and PO4 increasing downstream in both channels, while NO3-N concentration decreased in only one of the two channels. However, the temporal stability of these relationships is unknown. There is scope for considerable biological investigations in irrigation channels, which would have practical and theoretical outcomes.