Developing an Assessment System Aiming at River Ecosystem Protection in the Laohegou Stream, an Upstream Tributary of the Yangtze River

This study was carried out in the Laohegou stream with elevations ranging from 763m-1,948m, which drains a surface area of 110 km² over its 52 km length. It is one of the upstream tributaries of the Yangtze River located in the southwest of China. We collected fishes, benthic invertebrates and water samples in 32 sampling sites from the upstream to estuary during March 2012 and March 2013. In addition, eight environmental variables were recorded during each sampling: longitude, latitude, elevation, dissolved oxygen, wet width, water depth, water temperature and current velocity. Based on the data collected, we established a comprehensive assessment system aiming at the river ecosystem protection. We also examined how the Hengshanzi Dam affected aquatic organism assemblages in the river. The possible influences of the dam on aquatic environment for fish were analyzed, which may provide the reference for the ecological assessment of dam removal.