Spring phenology of the Arctic Ocean shelf production system

Abstract The shelf areas of the Arctic Ocean host some of the world’s most productive marine ecosystems, yet their under-ice early-season phenology and inter-trophic dynamics remain poorly understood amid rapid climate change. Addressing these knowledge gaps, we assembled a data-driven biophysical model integrating high-resolution ocean physics with biological dynamics across ice algae ( Nitzschia frigida ), Arctic copepods ( Calanus glacialis ), and fish larvae ( Boreogadus saida , reliant on C. glacialis nauplii). The model accurately recreated observed spatio-temporal production and recruitment patterns and revealed how the northern Barents Sea’s unique geography and ocean-climate facilitate key habitat and phenological synchrony, yielding large-scale biological export across the bio-region. Consequently, these geographically linked multi-trophic adaptations appear highly vulnerable to climate-forced shifts—e.g., proportion of C. glacialis in zooplankton is reduced up to 26% per 1 °C increase—as open-water area rises and ice-associated production and habitat degrades. Our findings thus provide timely insights for anticipating ecosystem disruptions from ongoing ice loss.