Abstract: Stable isotope analysis is an effective tool in studying mass and energy dynamics in aquatic ecosystem. Stable carbon isotope ratios (δ¹³C) are commonly used to trace consumers’ forging location; while stable nitrogen isotope ratios (δ¹⁵N) are used to estimate the trophic position of organism in the ecosystem. In this study, the food web of East Lake Taihu was constructed using stable isotope analysis with the aim of quantifying the trophic relationships among species and providing policy-makers scientific information for ecosystem-based management in Lake Taihu. Results showed that two trophic pathways were found in East Lake Taihu: the planktonic pathway and the littoralbenthic pathway, with phytoplankton and macrophytes as their carbon sources, respectively. The littoral-benthic pathway supports most of the fish populations. The top predators, carnivorous fishes such as culters, mandarin fish and catfish, dominate the highest trophic level.

Key words: Fanhe River watershed, soil and water assessment tool, boosted regression tree, quantitative analysis