The Spatiotemporal Patterns and Environmental Effects of Pelagic Communities in the Northwest Pacific Ocean Based on Sound Scattering Layer Descriptors.

The sound scattering layer (SSL) plays an important role in maintaining the structure and functioning of marine ecosystems. The spatiotemporal distribution of the SSL largely reflects the distribution of pelagic communities within the water column. Although acoustic data are widely used to investigate the distribution of communities within SSLs, a systematic framework for analyzing underlying environmental mechanisms remains limited. To address this, this study developed a model using SSL descriptors. SSL descriptors provide a new perspective for investigating community distributions in large marine ecosystems by capturing spatiotemporal variability in the structure and functioning of pelagic communities. We characterized the SSL using a suite of SSL descriptors. Descriptors indicative of community biomass then were used to fit generalized additive models. We applied this approach to an acoustic dataset collected in the Northwest Pacific Ocean during 2022-2024 to assess pelagic community distribution patterns and the key environmental drivers. This SSL descriptor-based modeling framework provides an innovative and robust approach for analyzing relationships between marine environmental variables and pelagic community distributions. Our results indicated that SSL descriptors are effective for monitoring and analyzing large-scale aggregations of pelagic communities. They support standardized monitoring of pelagic ecosystems and have high practical value in regions where species identification is difficult due to a lack of net sampling. This study provides a reference for further applications of SSL descriptors.