Ice algae in current water-ice environmental condition of the Arctic Ocean

Abstract

In the Arctic Ocean (AO) of today, there are noticeable changes in the composition and structure of biological communities inhabiting the water-ice environment. Over the past two decades, a decrease in the number of species of the sea ice flora and fauna has been noted in the central regions of the AO due to the changing physical environment of their habitat. In view of the current climatic instability in the AO, it is important to monitor and evaluate their composition, structure and dynamics of development. It is also important to preserve the methods of processing the materials collected in order to compare the state of the water-ice biota on similar spatial and temporal scales of the basin. In the present study, centric and pennate diatoms dominating in ice floristic communities were selected as indicators of changes. The aim of the work is to analyze the physical state of the water-ice environment and the species composition of ice diatoms based on the materials of the expeditions within the NABOS program at the Research Vessel (R/V) “Akademik Treshnikov” in the Arctic Basin in 2018 and 2021. The field work included observations of the state of the sea-ice cover in the area of the expeditions, the selection of ice cores to assess the salt composition and species composition of the algae, as well as CTD-sounding of the under ice — water layer. The analysis of the materials collected showed significant differences in the species composition and abundance of algae between the seasons, which indicates the formation of independent floristic communities in the current conditions of unstable physical environment in the central regions of the AO, which confirms the previously obtained results in the period 2007–2015. The materials under discussion were obtained in a short period of time and in limited spaces in the zones of production of annual ice in the waters of the shelf seas and zones of removal to the central regions of the AO. At the same time, short-term observations provide “instant” information about the qualitative and quantitative state of sea-ice biological communities. In order to obtain reliable estimates, long-term observations are needed, which may be organized in the near future based on new logistical approaches to the study of the marine Arctic.