Dense infestations of a peregrine oligochaete worm, Eukerria saltensis (Beddard), have been linked to rice crop failures in southern New South Wales, Australia. The influence of E. saltensis on water quality and rice plant establishment was investigated in a series of laboratory experiments using a flooded Riverina clay soil. Worm densities of 20 and 40 per container (2548 and 5096 worms/m2, respectively) significantly increased water turbidity after 7 days incubation. Longer incubation periods led to turbidity levels of over 500 NTU being achieved (40 worms per container, 21 days incubation). Water pH was significantly reduced by densities of 10, 20, and 40 worms per container after 7 days under cyclical illumination, however in continuous darkness significant changes in pH related to worm density were only found after 21 days incubation. Nitrogen as NH4+ and total phosphorus increased significantly in the overlying water in response to increasing worm densities after 21 days incubation, however nitrogen...