The Three Gorges Dam is the largest water conservancy project in the world, and the</p><p>Three Gorges Reservoir Area (TGRA) possesses precious fish resources. Currently,</p><p>due to the lack of efficient biodiversity monitoring tools, the precise evaluation of fish</p><p>community composition in a riverine reservoir has been restricted. Here, we</p><p>investigated fish resources using 12S-rDNA barcoding in the TGRA before and after</p><p>175 m water level during the first year of a 10-year Yangtze fishing ban. Our results</p><p>showed that the fish composition exhibited obvious seasonal differences. The</p><p>environmental water levels, land use, and spatial characteristics less influenced the</p><p>development of fish communities. Based on Infer Community Assembly Mechanisms</p><p>(iCAMP) by phylogenetic bin-based null model analysis, 66.12% of unexplained</p><p>variables were driven by stochastic processes of community assembly and</p><p>unmeasured key factors. We developed a growth-limiting index (GLI) and firstly applied</p><p>it for inferring fish environmental adaptability, revealing the growth adaption response</p><p>of reservoir fish species to environmental pressure. Compared to the downstream from</p><p>the dam, fish population growth at the low- or high-water levels was partly inhibited.</p><p>However, seven species of tiny or medium-sized fish showed strong adaptability in the</p><p>reservoir region at both water levels. Taken together, this study clarified the patterns of</p><p>fish community assembly in the TGRA and provided unique insights for chronic</p><p>monitoring fish diversities in a reservoir.
