Field surveys were conducted at the South Pond of Osaka Nanko Bird Sanctuary to examine the effect of sluice pipes on salinity, quality of bottom sediment and fauna of benthic animals. The installation of sluice pipes caused salinity increase with decreasing indicators of organic pollution of the bottom sediment. The fauna of benthic animals became rich in accompanied with salinity increase and a change from anaerobic sediment to aerobic one, which leaded to decreasing Chironomidae larvae and increasing gammarid animals. These findings suggest that the benthic fauna is still in the middle of biological succession and further observation should be done to confirm the restoration of benthic ecosystems of the pond.

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