Observations have shown that the arctic climate system is shifting. As river discharge increases, the sea-ice-free season lengthens, and air, sea and permafrost warm, the arctic shelf ecosystem can be expected to be transformed. Given the importance of fluvial discharge to shelf sea dynamics, the Lena Delta and Laptev Sea region are used measure the trajectory of processes critical to these transformations for the Arctic as a whole. This special issue examines processes in transition, from the land surface, hydrological inputs to the region of freshwater influence, over coastal mass transfer, water column chemistry of terrestrially-derived suspended and dissolved material, to fluvial transport to resulting changes in shelf hydrography. As a group, the special issue contributions create a multidisciplinary focus on land-shelf fluxes and their influence on the arctic shelf seas.