In Situ Ecological Floating Bed Remediation Alters Internal Trophic Structure: A Case Study of Meiliang Bay, Lake Taihu

Ecological floating beds are effective in mitigating lake eutrophication. To examine the effects of their in situ remediation processes on the food sources and trophic structures of consumers, particularly fish, this study used stable isotope techniques to compare cage enclosures, net enclosures, and natural lake area in Meiliang Bay, Lake Taihu. The results revealed that among basic carbon sources, only the δ13C values of phytoplankton and POM differed significantly, while most consumers showed no significant differences in carbon and nitrogen stable isotope characteristics across the three remediation areas. In cage enclosures, the food chain transitioned from being grazing-based, dominated by phytoplankton, to detritus-based, primarily relying on SOM. In contrast, net enclosures enhanced the utilization of phytoplankton. The trophic levels of most consumers in cage enclosures were significantly lower than those in net enclosures and the natural lake area. Trophic niche indices indicated that cage enclosures exhibited the highest trophic diversity and the lowest trophic redundancy. The in situ remediation using ecological floating beds altered the food resource conditions within the remediation areas due to differences in the degree of enclosure provided by the floating beds and interception facilities. These changes have consequently reshaped the internal trophic structure through trophic cascade effects.