- The structure of benthic macrofauna and bioassessment of water quality in cascade dammed reservoirs of Lancang River
- 交通运输部水运科学研究所, 北京 100088
- 云南大学生态学与地植物学研究所, 昆明 650091
- Abstract：Although the cascading hydropower exploitation can maximize utilization the water power resources, it can result in a large-scale disturbance on the river ecosystem. Benthic macrofauna are generally considered as an indicator of biological group for the aquatic ecosystem change and succession in cascade dammed reservoirs. In this study, the middle and lower reaches of Lancang River were selected as study areas. The benthic macrofaunas were sampled in cascade dammed reservoirs including Manwan and Dachaoshan in 2016. The structure, distribution pattern of benthic macrofauna, and the bioassessment of water quality based on the biotic index (BI) were analyzed and performed. The results showed that the species composition of benthic macrofauna were mainly Oligochaeta, Mollusca, and chironomids, which belonged to Insecta. The dominant species of benthic macrofauna was Corbicula fluminea, which belonged to Mullusca. The density and biomass of benthic macrofaunas in the lacustrine zone were significantly higher than those in transition zone. As for the functional feeding group, the density composition of benthic macrofaunas was dominated by the gatherer-collector (GC) and filter-collector (FC), while the biomass composition was dominated by the filter-collector (FC). The abundance/biomass curves (ABC) and biotic index (BI) analysis indicated that the stability of benthic macrofauna and the water quality in upstream Manwan reservoir were better than that in downstream Dachaoshan reservoir, implying that the water quality gradually got worse in these cascading reservoirs along the longitudinal gradient of the river. The structure, distribution pattern of benthic macrofauna, and water quality revealed obviously cumulative and eutrophication effects caused by cascading reservoir operation in Lancang River.