Abstract
Permanent sea-ice cover and low primary productivity in the mostly ice-covered Central Arctic ocean basins result in significantly lower biomass and density of macrobenthos in the abyssal plains compared to the continental slopes. However, little is known on bathymetric and regional effects on the macrobenthos diversity. This study synthesizes new and available macrobenthos data to provide a baseline for future studies of the effects of Arctic change on macrofauna community composition in the Arctic basins. Samples collected during three expeditions (in 1993, 2012 and 2015) at 37 stations on the slope of the Barents and Laptev Seas and in the abyssal of the Nansen and Amundsen Basins in the depth range from 38 m to 4381 m were used for a quantitative analysis of species composition, abundance and biomass. Benthic communities clustered in five depth ranges across the slope and basin. A parabolic pattern of species diversity change with depth was found, with the diversity maximum for macrofauna at the shelf edge at depths of 100–300 m. This deviates from the typical species richness peak at mid-slope depths of 1500–3000 m in temperate oceans. Due to the limited availability of standardized benthos data, it remains difficult to assess if and how the significant sea-ice loss observed in the past decade has affected benthic community composition. The polychaete Ymerana pteropoda and the bryozoan Nolella sp. were found for the first time in the deep Nansen and Amundsen Basins.
Highlights
The deepest parts of the Central Arctic, including the abyssal plains of the Nansen and Amundsen Basins separated by the Lomonossov Ridge, are among the least studied areas of the global oceans
Macrobenthos of the Central Arctic Ocean is controlled by food availability
We summarized published data on the biomass and abundance for the depth ranges used in our study (Table 7)
Summary
The deepest parts of the Central Arctic, including the abyssal plains of the Nansen and Amundsen Basins separated by the Lomonossov Ridge, are among the least studied areas of the global oceans. Most surveys of Arctic benthos have been conducted on the shelf or upper slope, whereas data from the deep basins remain rare and scattered in time and space. First data on the deep-sea fauna of the Central Arctic were obtained in 1935 using trawls and dredges not suitable for collecting quantitative samples. Qualitative descriptions of the Central Arctic bathyal and abyssal fauna were made by Soviet expeditions on the vessels Sadko in 1935–1937 and F. First quantitative data using mini-LUBS corer and “Okean” grabs were collected in the 1970s in the Canadian Basin from the American Fletcher’s
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