Benthic invertebrates investigation in the East River and habitat restoration strategies

The stream ecology of the East River is studied using benthic macro-invertebrates as indicator species. Samples were taken from 12 selected sites with different environmental conditions, from the upper reaches to the lower reaches. Four sites were selected to assess restoration strategies. The taxon richness, number density, biodiversity, and bio-community indices of benthic invertebrates remain at a relatively high level in the upper and middle reaches of the East River, but reduce to nearly zero in the lower reaches. The main ecological stresses are loss of habitat because of reclamation and the separation of riparian waters from the river. An important restoration strategy is to create multiple habitats with high habitat diversity, such as riparian lakes, wetlands, backwaters and sluggish flow zones, and to reconnect separated oxbow lakes with the river. Riparian waters should be managed in a similar way in Zengjiang Bay, allowing river flow to carry fine sediments into the riparian waters. Consequently, the fine sediment can deposit to form a mud layer. Fishes and invertebrates may live and spend parts of their life cycle in riparian waters. The Fengshuba Dam causes instantaneous fluctuation in flow discharge, and the aquatic ecology in the downstream reaches is impacted. A restoration strategy is required to adjust the operation scheme of the reservoir. Slope erosion and landslides also impact the stream ecology; the main restoration strategy for this is reforestation.