Research
| Title： | A pulse-stairstep longitudinal pattern of larval fish assemblages in a channelized floodplain river downstream of a dam: dominant influences of major tributaries with a confluence refuge concept |
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| First author： | Cao, Juan; Cheng, Fei; Wang, Zhen; Song, Yiqing; Xie, Songguang |
| Journal： | HYDROBIOLOGIA |
| Years： | 2023 |
| DOI： | 10.1007/s10750-023-05281-9 |
| Abstract： | We investigated larval fish assemblages in the Yangtze River downstream of the Three Gorges Dam to test the influence of tributary inputs on the longitudinal recovery pattern of the assemblages from negative impacts of dam regulation. Larval fish assemblages showed a pulse-stairstep longitudinal pattern. Specifically, two pulses of dramatically increased abundance of larval fish occurred immediately downstream of the confluences of Dongting Lake and Hanjiang River. Three stairsteps of larval fish abundance were observed, which were separated by the confluences of Hanjiang River and the Poyang Lake watershed inputs. Larval fish abundance kept relatively constant within a stairstep and increased apparently in the downstream direction among the stairsteps. While fish assemblages upstream of the confluence of Hanjiang River were highly variable, whereas those downstream were relatively similar. Our results demonstrated that tributary inputs shaped the longitudinal recovery pattern of the larval fish assemblages. We proposed the confluence refuge concept suggesting that confluence areas provide refuges and nursery grounds for fishes in the suboptimal river section negatively impacted by the dam. Hence, conserving the confluence areas of major tributaries and maintaining lateral connectivity of floodplain lakes are critical for fishery resource enhancement in such dam-regulated and highly channelized floodplain rivers. |
