State of Benthic Communities in the Bays of the Novaya Zemlya Archipelago (Kara Sea) in 2020

Abstract— In 2020, the benthic communities of Rusanova Bay were investigated for the first time, alongside the repeated surveys conducted in Blagopoluchiya and Tsivolki Bays (Novaya Zemlya archipelago, Kara Sea). Mass extinction of the adult component of the bivalve Portlandia arctica population, which had been dominant from 2013 to 2016, was observed in the inner parts of these bays. In all three bays, the benthic communities were primarily composed of the bivalves Mendicula ferruginosa, juvenile Ennucula tenuis, Portlandia arctica, and Yoldiella spp. In Rusanova Bay, the number of small and juvenile bivalves was the highest, comprising 92% of the total density and reaching an abundance of 2900 ind/m². The high proportion of juveniles indicates the instability of the benthic fauna, which should lead to a rapid transformation of the inner bay communities over the next few years. It is proposed that environmental factors such as terrestrial runoff, sedimentation, and the temperature characteristics of the near-bottom layer, along with the invasion of the snow crab Chionoecetes opilio, have contributed to the observed changes in the benthic communities.