N) provides a powerful tool for estimating the trophic positions of consumers in food webs. We measured δ¹⁵N in 28 fish species and 26 invertebrate species that were collected from Liaodong Bay June and August, 2010. The trophic levels of these organisms ranged from 2.98 to 4.84, but were generally within the range of 3.70–4.56. δ¹⁵N values changed in a large proportion (50%) of fish between July and August, suggesting that δ¹⁵N values vary among species and seasonally. The largest increase wasPlatycephalus indicus (1.84‰). Furthermore, δ¹⁵N values decreased in 87.5 of the invertebrates in August. The decrease in 6 invertebrate species was > 1‰ (37.5), suggesting that invertebrates exhibit greater seasonal variation in δ¹⁵N than fish. We compared the δ¹⁵N values for 10 invertebrate species in the nearshore waters and offshore waters of Liaodong Bay to determine whether the inshore seawater environment and ecosystem is influenced by anthropogenic nitrogen inputs.