The work is devoted to the problems of mutual adaptation of two invasive commercial crab species - red king crab (Paralithodes camtschaticus) and snow crab (Chionoecetes opilio) - and the recipient ecosystem of the Barents Sea.
Data on the distribution of megabenthos communities obtained for the periods 2006-2010, 2011-2015 and 2016-2020 are presented. The dynamics of invasive crab populations and related changes that have occurred in the bottom communities of the Barents Sea during these periods are analyzed. Mechanisms of crab impact on bottom communities and prospects for further development of the Barents Sea water area by them are discussed.
The study is based on the results of quantitative and taxonomic analysis of bycatch in 6010 trawls with trawl "Campelen-1800", performed in the Barents Sea in 2006-2020 during the joint Russian-Norwegian ecosystem survey on vessels of Polar branch of FGBNU "VNIRO" and Institute of Marine Research (IMR, Norway, Bergen, Trømso).
During 2006-2010, red king crab dominated in megabenthos communities around Murmansk Bank and Kaninskaya Bank. Later in 2016-2020 it had spread north and east, and dominated the megabenthic communities also around Kanin Nos Peninsula, Kolguev Island, and at the southern slope of the Goose Bank. In 2006-2010 snow crab started to increase in numbers near the Novaya Zemlya Archipelago; only around the Goose Bank it was subdominant in the soft bottom megabenthic communities. During 2011-2015 snow crab started to dominate in megabenthic communities around the Goose Bank and the Novaya Zemlya Bank, the northern part of the Central Bank; and at the same time continued to increase as a subdominant species in almost all megabenthic communities near the Novaya Zemlya Archipelago. Later in 2016-2020 snow crab has dominated the megabenthos in the entrance to the Kara Sea between Novaya Zemlya Archipelago and Franz Josef Land Archipelago, on slopes of the Novaya Zemlya Bank, near the Central Bank, and in the South Novaya Zemlya Trench. The area with subdominance of snow crab increased and eventually covered the area from the Franz Josef Land and Novaya Zemlya Archipelago to the Perseus Bank toward the west and to the Pechora Sea in the south. The results show that within the current climatic condition red king crab will continue to spread and to become a dominant member of megabenthic communities of the southeastern Barents Sea (mainly in the Pechora Sea). Snow crab will continue to migrate from the east to the western part of the Barents Sea all the way to the Spitsbergen archipelago, where similar benthos communities exist, in case of cooling in the Arctic spreading will go faster. A possible future scenario would be that the shallow waters of the Spitsbergen archipelago will be the new reproductive center of snow crab population in the Barents Sea together with the present center near Novaya Zemlya Archipelago.