Effects of “Atlantification” on ecosystem properties of the Barents Sea investigated through qualitative loop analysis

Atlantification exposes northern and Arctic ecosystems to events that can drastically modify their structure and functions. One such event is species migration, which has been documented in the Barents Sea, where boreal species invaded the northern part of this ecosystem, reshaping its food webs. Although studies have forecasted deep consequences of this altered structure on ecological functions, it remains an open question which functions are more likely to be affected and with what consequences. In this paper we focus on ecosystem responses to stress, which could change as food web connectivity increases following the entry of boreal species. Because environmental stress may generate pulse and press perturbations, we analysed the food webs of the Northeast and the Northwest sectors of the Barents Sea before and after the immigration of boreal species, focusing on stability and resistance properties. Using qualitative loop analysis, our results show a decreased capacity to withstand pulse perturbation in the post-invasion models, but the same systems seem to be characterized by grater inertia and higher resistance to press perturbations.