Abstract <p>Bivalves (Bivalvia) are one of the main components of Arctic ecosystems, but their trophic ecology is poorly understood. This study presents the trophic characteristics of bivalves found along a submeridional transect from the Lena River delta to the northern shelf boundary during an expedition aboard the R/V <i>Akademik Mstislav Keldysh</i> (cruise no. 73) in the Laptev Sea in September–October 2018. Based on the abiotic characteristics of the sampling stations and the δ¹³C values in the soft tissues of bivalves, four groups of stations were identified: delta-proximal stations, midshelf stations, methane seeps stations, and non-methane stations at the northern shelf boundary. A decrease in the influence of terrigenous organic matter carried by the Lena River runoff on the carbon isotope composition of bivalves was observed with increasing distance from the delta: delta-proximal stations (δ¹³C –28.1 ± 0.5‰), midshelf stations (δ¹³C –24.9 ± 0.3‰), and background stations near the northern shelf boundary (δ¹³C –22.2 ± 0.9‰). At methane stations, the δ¹³C values in bivalve tissues were lower than at background stations (–27.6 ± 0.5 and –22.2 ± 0.9‰, respectively).</p>