Decadal community structure shifts with cold pool variability in the eastern Bering Sea shelf

Area of Science:

• Marine Ecology
• Oceanography
• Fisheries Acoustics

Background:

• The eastern Bering Sea (EBS) features a cold pool, a subsurface layer below 2°C, influenced by seasonal sea ice (SSI).
• Cold pool dynamics are critical for regional zooplankton and fish populations.
• Understanding these dynamics is vital for predicting ecosystem changes.

Purpose of the Study:

• To assess the relationship between biological scattering communities and cold pool variations in the EBS.
• To investigate how acoustic backscatter changes with temperature and SSI over different climate regimes.
• To identify potential indicators for ecosystem regime shifts.

Main Methods:

• Utilized multifrequency (200 and 460 kHz) acoustic backscatter data from 2008-2018.
• Coupled acoustic data with bottom temperature and regional SSI data.
• Analyzed data across cold (2006-2013) and warm (2014-2018) regimes.

Main Results:

• Acoustic backscatter was significantly higher (2 orders of magnitude) during the cold regime compared to the warm regime.
• Multifrequency analysis revealed shifts in frequency-dependent scattering communities during the warm regime.
• Seasonal sea ice was a stronger predictor of biological scattering in the cold regime, while temperature and SSI had equal predictive power in the warm regime.

Conclusions:

• Coupled cold pool and frequency-dependent scattering dynamics may serve as indicators of ecosystem regime shifts.
• These findings can inform management strategies for the EBS and adjacent Arctic ecosystems.
• Acoustic data provide a valuable tool for monitoring changes in marine ecosystems.