During the survey, 64 species of fishes belonging to 9 families and 5 orders were collected from the Three Gorges riverine section of the Yangtze River. Owing to the influence of Three Gorges Dam (TGD) and the Gezhouba Dam (GZD), species diversity of fish was obvious lower in the downriver section of GZD than that in the upriver section of TGD.
As a whole, the influence on POM by the construction of TGD and GZD was much less than those by the variation of physical discharge and riverine temperature of the Yangtze River.
Different fishes (shrimps) showed different temporal variations of δ13C and δ15N. The variation of δ13C and δ15N of carnivorous fishes (Siniperca chuatsi, Culter mongolicus mongolicus, Silurus asotus) from the Zigui section suggested that they held relative steady food source in the whole year, and had a ingesting climax in May and June. The δ13C of Pelteobagrus nitidus and P. vachellii varied obviously in the Zigui section (the upriver of TGD), and kept stable in the Sandouping section (the downriver of TGD).
Spatial variations of δ13C and δ15N of fishes (shrimps) suggest that fishes from the upriver of TGD (Wanzhou, Yunyang, Wushan, Zigui) ingested much more allochthonous food than fishes from the downriver of TGD and GZD.δ13C of some fish Generally, δ13C of fishes had a degressive tendency along with the flow direction of the Yangtze River.δ13C of the fish food webs of the Three Gorges section showed a wavy variation, with Zigui on the wave crest, Yunyang on the trough, and the wavy declining from Zigui to Yichang.