Xinyu Wang’s research while affiliated with Shanghai Ocean University and other places

The characteristics of macrobenthic community structure can accurately indicate the ecological health of aquatic environments. To elucidate the spatiotemporal responses of macrobenthic communities and environmental factors in reservoirs, this study investigated macrobenthos and environmental parameters in Yinghu Lake during spring (May), summer (August), and autumn (November). The results showed that the trophic level index (TLI), total nitrogen (TN) and total phosphorus (TP) were significantly higher and pH was significantly lower (P < 0.05) at the developed sites (DS) than at the undeveloped sites (UDS). The survey identified 32 macrobenthos species representing 3 phylums and 5 orders. PERMANOVA analyses showed that the macrobenthic community structure of Yinghu Lake differed significantly between regions, Limnodrilus hoffmeisteri from the gathering collectors (20.47%) and Corbicula fluminea from the filtering collectors (7.82%) were the primary species driving the differences. The results of the two-way ANOVA indicated that species richness, the Margalef index (D), and the functional feeding group Margalef index (FFG-D) were significantly lower in summer than in autumn (P < 0.05). FFG-D was also significantly lower at the DS compared to the UDS (P < 0.05), while the interaction effects of season and region on these indicators were not significant (P > 0.05). Redundancy analysis (RDA) and generalized additive modelling (GAM) indicated that the permanganate index (CODMn) and total dissolved solids altered the macrobenthic community structure towards oligochaete and gathering collectors-dominated assemblages. Moreover, macrobenthic diversity was constrained by high total dissolved solids concentrations, sediment organic carbon (OC_s), soluble reactive phosphorus (SRP), low sediment total phosphorus (TP_s), high water temperature, and deep water. In summary, the spatiotemporal variations in water quality and macrobenthos communities in the reservoir were influenced by natural conditions and anthropogenic disturbances. This study provides valuable insights into the spatiotemporal dynamics of macrobenthic communities and contributes to a more comprehensive understanding of the role of biodiversity in maintaining the stability of large reservoir ecosystems.

The Danjiangkou Reservoir is the water source of the middle route of China’s South-to-North Water Diversion Project, encompassing the Dan Reservoir and Han Reservoir. However, little is known about the ecological functions of this important ecosystem. Based on a survey conducted in 2023 in the Dan Reservoir, a mass balance model was constructed using Ecopath with Ecosim 6.6 software to characterize its food web structure and ecosystem properties. The model consisted of 18 functional groups, including producers, consumers, and detritus, covering the entire process of energy flow in the ecosystem. The outputs indicated that the fractional trophic level of functional groups in the Dan Reservoir ecosystem ranged from 1.00 to 3.50. The ecotrophic efficiencies of the main economic fish species were all less than 0.9, and the ecotrophic efficiencies of phytoplankton and detritus were less than 0.5. There were two main food chains: the detritus food chain (39%) and the grazing food chain (61%). The total energy transfer efficiency between trophic levels was only 6.02%, and there was a significant phenomenon of energy transfer blockage between trophic levels II and V. Analysis of the overall characteristics of the ecosystem revealed that the total primary production to total biomass (67.96619), connectance index (0.274), and Finn’s cycling index (2.856) of the Dan Reservoir ecosystem all indicate that the ecosystem is immature, with low nutrient recycling efficiency and poor resistance to external disturbances. This may be related to the low proportion of silver carp and bighead carp in the reservoir and the unreasonable structure of the fish community. Our results suggest that it is necessary to scientifically adjust the structure of the fish community, enhance the proportion of filter-feeding and omnivorous fish to improve the energy flow efficiency, and promote the maturity and stability of the Dan Reservoir.