Effects of Cascading Hydropower Dam Operation on Benthic Macroinvertebrate Assemblages and Sediments in the Lancang River

Abstract

Li, J.P.; Cheng, D.M.; Zhao, A.D.; Liu, S., and Xuan, H., 2020. Effects of cascading hydropower dam operation on benthic macroinvertebrate assemblages and sediments in the Lancang River. In: Guido Aldana, P.A. and Kantamaneni, K. (eds.), Advances in Water Resources, Coastal Management, and Marine Science Technology. Journal of Coastal Research, Special Issue No. 104, pp. 465–472. Coconut Creek (Florida), ISSN 0749-0208.The operation of cascading hydropower dams may have complex and long-term effects on river ecosystems, where benthic macroinvertebrate assemblages and sediments are indicators of changes in dynamics. This study investigated how cascading hydropower dams in the middle and lower reaches of the Lancang River in China affect benthic macroinvertebrate assemblages and sediments. Benthic macroinvertebrate assemblages and sediments were sampled in the Manwan and Dachaoshan cascading dams in 2016. The structure and distribution pattern of benthic macroinvertebrate assemblages, and heavy metal and nutrient pollution in sediments were analyzed. The benthic macroinvertebrate assemblages were mainly composed of species from Oligochaeta, Mollusca, and Insecta. Corbicula fluminea (Mollusca) was the most dominant species. The potential ecological risk index of heavy metals was higher in the upstream of the Manwan dam (M1-M3), while nutrient pollution in sediments was higher in the downstream of the Dachaoshan dam (D1-D3). The correlation analysis revealed that the density of Mollusca was significantly correlated with heavy metal pollution in sediments, while the density of Oligochaeta was significantly correlated with nutrient pollution in sediments. Hence, the operation of cascading hydropower dams has significant accumulation effects on benthic macroinvertebrate assemblages, and heavy metal and nutrient pollution in sediments, in river ecosystems.