[A-OS15] Marine ecosystems and biogeochemical cycles: theory, observation and modeling

[AOS15-04] Environmental and biotic filters regulate fish community structure in the Eastern Bering Sea

*Irene Alabia^1,2, Jorge García Molinos¹, Takafumi Hirata¹, Hiromichi Ueno³, Sei-Ichi Saitoh¹ (1.Arctic Research Center, Hokkaido University, 2.International Arctic Research Center, University of Alaska Fairbanks, 3.Faculty of Fisheries Sciences, Hokkaido University)

Keywords:Community assembly processes, Biodiversity, Joint species distribution models, Eastern Bering Sea

Assembly processes shape the identity and abundance of species within ecological communities and are important for conserving biodiversity under the ubiquitous threats of climate change. Here, we inferred the influence of environmental and potential biotic associations on fish community structure in the Eastern Bering Sea across three decadal periods (1993-2023). We constructed decadal-based joint species distribution models to relate species information, environmental factors, functional traits, and phylogeny of 58 fish taxa to quantify the contributions of environmental and biotic filters in regulating the community structure. Our findings showed that changes in species abundances were comparably driven by environmental (38-45%) and biotic (43-51%) filtering, albeit the latter's contribution increased over time. The influence of traits on species responses to environmental factors was highest in the last decade (2013-2023; 53%), accompanied by a phylogenetically structured signal, suggesting shared ecological responses of related taxa. Residual species-to-species associations showed the highest (lowest) non-random co-occurrences beyond those explained by environmental covariates in the second (last) decade. The combined, yet varying inter-decadal impacts of environmental and biotic assembly processes altered the composition and abundance of the fish community in the area, raising significant repercussions on ecosystem structure, function, and provision of services.