[Impacts of Spartina alterniflora invasion on the benthic food web in the Yellow River Delta during autumn].

Spartina alterniflora was introduced into the Yellow River Delta (YRD) in 1990 with the purpose of shore protection and siltation accretion. However, it spread rapidly and became a severe threat to the local coastal wetland ecosystem. To assess the impacts of S. alterniflora invasion on the benthic food web, we sampled the potential food sources of macrobenthos in November 2020, analyzed the trophic level and the benthic food web structure based on stable isotope technique. Results showed that the average δ13C values of macrobenthic food sources followed an order: sediment organic matter (SOM) > S. alterniflora > benthic microalgae > particulate organic matter (POM) > Suaeda salsa. The average δ15N values significantly differed among food sources, ranging from 1.24‰ to 9.03‰. The trophic levels of different macrobenthos ranged from 1.73 to 4.19, of which the bivalve species was the lowest one. S. alterniflora and the decayed debris were the most important food sources for macrobenthos, but without any impact on the trophic level structure of macro-benthos. In conclusion, Spartina alterniflora invasion distinctly changed the composition of food sources of macrobenthos through a "bottom-up" effect, which would probably impact the local food web structure in the YRD wetland.