Spatio-temporal characteristics of demersal fish community in the Chukchi and northern Bering Seas: significant distributional records and interannual variations in species composition and biodiversity

The Chukchi and northern Bering Seas, which serve as the only gateway for Pacific water entering the Arctic Ocean, have experienced profound declines in sea ice cover as well as increases in oceanic temperature. In this region, fish responses to climate change are of widespread concern, but time-series data are limited because of the harsh environment. Four Chinese National Arctic Research Expeditions with stations spanning substantial latitudes in both the Chukchi and northern Bering Seas were conducted in alternating summers (July-September, every 2 years) from 2010 to 2016, indicating that demersal fish had large spatial and interannual fluctuations in species composition and biodiversity. A total of 58 fish species were identified, including several taxa that were rarely sampled previously or repeatedly encountered in the border regions. The significant distributional records of these taxa may correspond to the probabilities that species have extended beyond the documented distribution limits and the interchanges between the Pacific and Atlantic faunas are promoted under the influence of climate change. The fish biodiversity patterns were quantitatively described using seven indices such as species richness and taxonomic diversity indices. The spatial and temporal variations in species composition and biodiversity may be related to differences and interannual oscillations in water mass and tight pelagic-benthic coupling. Additionally, our analyses suggested that fish communities in the Chukchi Sea, where the consequences of climate change seem to be more serious because of the simpler food web and the proximity to the central Arctic Ocean, appeared to be less affected by the currently changing environment than those in the northern Bering Sea. Time-series surveys would establish a foundation for distinguishing between acclimation to climate change and natural fluctuations.

Automated summary

Research conducted in the Chukchi and northern Bering Seas found significant spatial and interannual fluctuations in demersal fish species and biodiversity, likely due to differences and interannual oscillations in water mass and tight pelagic-benthic coupling. The study also suggested that fish communities in the Chukchi Sea are more seriously affected by climate change compared to those in the northern Bering Sea, possibly due to simpler food webs and proximity to the central Arctic Ocean. Time-series surveys could help distinguish between acclimation to climate change and natural fluctuations.