Characterization of pelagic communities in the Pacific sector of the Arctic Ocean using a broadband acoustic system, net samplers, and optical instruments.

Rising Arctic temperatures are causing substantial declines in sea ice, altering ice retreat and formation in the Pacific Arctic and impacting marine communities. Despite the significant challenges facing the Pacific Arctic, there are still gaps in our understanding of the environmental impacts on pelagic communities, particularly sound scattering layers (SSLs), and their distributions in the southern Chukchi Sea (SCS), northern Chukchi Sea (NCS), and East Siberian Sea (ESS). This study utilized a wideband autonomous transceiver, net samplers, and optical instruments to explore SSLs in the Pacific Arctic, detailing their relationships with hydrographic properties. The findings indicated a greater vertical distribution of pelagic communities in the SCS than in the NCS and ESS. Significant differences in frequency spectra patterns were observed between the SCS and both the NCS and the ESS, though not between the NCS and the ESS. The correlations between the broadband acoustic and hydrographic values were generally weak to moderate. Elevated acoustic values in the SCS were linked to higher water temperature, dissolved oxygen, and chlorophyll and lower salinity. This study also revealed the behavioral properties of individual pelagic animals and identified Ctenophores and Copepods as the most abundant classes based on camera images and net samples. This research offers crucial insights into the distribution and interactions of pelagic communities with environmental factors, laying the groundwork for understanding climate change impacts. Additionally, this paper presents the first findings of frequency spectra from a broadband system in the Arctic Ocean. • Rapid decline of Arctic Sea ice causes a growing interest in fisheries resources. • The regional difference of SSL, the indicator of fisheries resources, was observed. • The frequency spectra of SSLs were significantly different across the Pacific Arctic. • Acoustic values of SSLs were closely related with essential environmental factors. • The results offer crucial insights into the pelagic communities in the Arctic Ocean. [ABSTRACT FROM AUTHOR]