The interaction processes of the fish assemblages between the Yangtze River and Poyang Lake, China

Abstract

Lateral hydrological connectivity (LHC) maintains the high biodiversity and ecosystem functions in the river–floodplain system. We investigated the changes in the taxonomic and functional composition of fish assemblages in the lateral connection channel between the Yangtze River and Poyang Lake, China, during the dry and wet seasons and which factors drive the changes. The results indicated more lake‐residence species and fewer river–lake species in the channel during the wet season than the dry season, leading to significant seasonal differences in taxonomic compositions and trait patterns. Water temperature, water level and fish migration influenced fish assemblage structures in the channel. Water‐level fluctuations that limited food sources and suitable habitats promoted the migration of riverine and lake‐residence fish during both seasons. Water temperature and level also significantly influenced species‐specific migration. Water temperature influenced the spawning migration of river–lake fish during the wet season. Based on these results, we found temporal species‐specific migration dynamics in fish assemblages in the lateral channel that were related to species’ life‐history traits. Therefore, we inferred that the temporal–spatial interaction of the fish community in the river–floodplain system is essentially derived from the evolutionary adaption to the monsoon climate. This process is well studied and predictable, and can be beneficial for managing the river–floodplain systems. The invasion risk of the exotic species, including fish and macroinvertebrates, should be assessed before implementing LHC restoration.

Signals of Potential Species Associations Offer Clues about Community Organisation of Stream Fish across Seasons

“…Considering correlations between network nestedness and the unexplained residuals from the Boral model, we speculate that species competition may also play a key role in structuring fish communities along the Qiupu River. This is a reasonable suggestion, not least because fish usually occupy relatively similar niches in streams, which may lead to strong competition between co-occurring species, especially during the dry season, when only small habitat patches and few food resources are available for these animals [63,64].…”

Niche position accounts for the positive occupancy–abundance relationship of lake fishes

“…Five large rivers (i.e. Xiuhe River, Ganjiang River, Xinjiang River, Fuhe River and Raohe River) flow into Poyang Lake, and the water eventually flows northward into the Yangtze River through a narrow outlet, thereby forming a complex river–lake connected ecosystem (Zhang et al., 2021). The main terrain types in this area are mountains (36%), hills (42%), plains (12%) and water (10%).…”

Impact of hydrological processes on wetland landscapes and wintering migratory birds in a large floodplain lake (Poyang Lake, China)

“…In October, bird populations (including white cranes, bean geese and swan geese) begin to reach a peak in December and the following January, then decline again the following February (Zou et al, 2021). In addition, Poyang Lake is home to a variety of important and rare aquatic organisms in the Yangtze River Basin, such as the Yangtze River dolphin, cochineal fish and knife fish, and contains abundant fish species (Zhang et al, 2021). 1).…”