Macroinvertebrate Community Structure in Three‐Gorges Reservoir, China

Abstract

We investigated the macroinvertebrate community structure in Three-Gorges Reservoir during a three-year period after the reservoir became operational. Comparison with data of previous authors obtained before the damming showed that the benthic community changed drastically in the reservoir. Oligochaetes and chironomids dominate the present community. An apparent annual cycle in the benthic community (expressed as richness, density and community type) was found in the second year, lagging one year behind the annual cycle of transparency. After the second year, a Nais-Polypedilum community type, occurring in winter and spring with low inflow discharge and high transparency, was followed by a Limnodrilus community type that occurred in autumn and summer under contrasting conditions. Despite river regulation and damming, it appeared that macroinvertebrates in subtropical canyon-shaped reservoirs remained influenced by floods.

Spatial Distribution of Macroinvertebrate Community along a Longitudinal Gradient in a Eutrophic Reservoir‐Bay during Different Impoundment Stages, China

“…Little is known about the basic ecological information of this species. Some studies showed that they are frequent in Yangtze River, especially in January and April (SHAO et al, 2008;ZHANG et al, 2010). In addition, this study showed that they were dominant in spring.…”

“…In the Xiangxi Bay, chironomids had relatively higher abundances in the first year after the impoundment of TGR, but from August 2004, oligochaetes became the dominant group (relative abundance of total density over 90%), with the highest density in the middle reach (SHAO, 2008). Compared to that in the 1st stage (over 15000 ind/m 2 in April 2006, estimated from SHAO (2008)), the macroinvertebrate density of the bay declined dramatically from the 2nd impoundment stage, but the dominance of oligochaetes was not affected.…”

Changes in water types under the regulated mode of water level in Three Gorges Reservoir, China

“…The mainstream and Xiangxi Bay of the reservoir both are main areas ( Fig. 2) of long term ecological observation and research carried out by the Xiangxi Ecosystem Station, Chinese Academy of Sciences and China Three Gorges Project Corporation, and more detailed descriptions of the study areas can be found in the published literature (e.g., Shao et al, 2008;Xu et al, 2009a,c;Zhang et al, 2010).…”

“…Eutrophication and algal blooms have proven to be stubborn environmental problems all over the world for decades (Schindler, 2006;Smith et al, 2006), and also have become major problems of aquatic ecosystem degradation after many river dammings (Ha et al, 2003). Long-term studies of phytoplankton succession showed increases in algal biomass in many regulated rivers, resulting from increased nutrient inputs coupled with hydrologic changes (Górniak et al, 2003).…”

“…The impacts of TGD on ecological processes of water body have caused concern to aquatic ecologists worldwide (Cai and Hu, 2006). Many ecological studies of TGR after the first impoundment have been published in Chinese and international journals, including suspended solids (Xu et al, 2009a), water eutrophication (Cai and Hu, 2006;Xu et al, 2010a), algal blooms (Ye et al, , 2007Xu et al, 2009b,c), phytoplankton (Zeng et al 2006), zooplankton (Xue et al, 2006), and macroinvertebrates (Shao et al, 2008). For example, it was found that water residence time is an important regulatory factor for seasonal dynamics of suspended solids (Xu et al, 2009a), trophic status (Xu et al, 2010a) and water clarity (Xu et al, 2010b) after the first impoundment.…”