Abstract: Thirty three fishes and nine species of invertebrates were collected in the Yangtze Estuary during November 2014 to October 2015. The isotope composition and trophic level of common fishery organisms were analyzed by using the stable carbon and nitrogen isotope techniques. The results showed that fishery organisms had great variations in stable carbon and nitrogen isotopes. δ¹⁵N values of fish ranged from 9.26‰ to 15.39‰, and δ¹³C values ranged from -29.78‰ to -14.25‰; invertebrates showed δ¹⁵N values between 7.73‰ and 13.53‰, and δ¹³C values from -22.22‰ to -14.84 ‰. We calculated the trophic level of each consumer by Scapharca subcrenata as baseline animal. The result showed that the trophic level of fishes ranged from 2.49 to 4.60 (including 3 levels); carnivorous Acipenser sinensis showed the highest level (4.60±0.02), while Hypophthalmichthys molitrix showed the lowest level (2.49±0.02); invertebrates ranged from 2.00 to 3.84 (including 2 levels), and crab Eriocheir sinensis showed the highest level (3.84±0.02). There was a positive relationship between trophic level and body length of Collichthys lucidus, Lateolabrax maculatus, Acanthogobius ommaturus. By analyzing the established estuarine food web continuous nutrition spectrum, this study provides a theoretical basis for development and protection of the fishery resources in the Yangtze Estuary.

Key words: vegetation type, regression model., soil nutrient, spatial prediction, Kriging