Non-indigenous plant expansion reconstructing benthic food web in tidal flats of China

Coastal wetland ecosystems rely on a delicate balance between nutrient contributions from primary producers and the adaptive feeding strategies of macrobenthic consumers. This study utilizes a dual-tracer approach, combining stable isotope analysis (δ¹³C, δ¹⁵N) with fatty acid biomarker profiling, to investigate the ecological and biogeochemical mechanisms driving organic matter dynamics in habitats influenced by non-indigenous vegetation. The introduction of Spartina alterniflora and Kandelia obovata not only broadens the carbon source baseline of native mudflats, creating a bipolar isotopic spectrum but also reshapes macrobenthic food web structures. S. alterniflora, a rapidly decomposing C4 plant, shifts energy pathways from grazing based to detritus-based, which promotes short-term resource utilization, shortens food chains, and intensifies interspecific competition. Conversely, K. obovata contributes to a more diverse organic matter pool through its complex root architecture and slower-degrading litter, enhancing long-term ecosystem stability. Our findings demonstrate that using both isotopic tracers and fatty acid profiles effectively delineates spatial heterogeneity, trophic interactions, and the cascading effects of plant invasions on nutrient cycling. These insights highlight the need for flexible, stage-specific management strategies-ranging from dynamic monitoring and local biological substitution to integrated mechanical removal and mangrove restoration-to mitigate potential ecological destabilization and optimize blue carbon functions.