Seasonal dynamics of prokaryotic community in Arctic sediments of the Pasvik River by multiplex antibody microarray profiling

Understanding the functional dynamics of benthic microbial communities in Arctic rivers is essential for predicting ecosystem responses to environmental change. This study investigated seasonal immunological profiles and functional guild dynamics of benthic microbial communities in the Pasvik River (Arctic Norway) using multiplex antibody microarrays. Sediment samples collected in spring (May) and summer (July) from nine stations, spanning riverine to brackish estuarine zones, were analysed through Fluorescence Sandwich Microarray Immunoassays (SMI) to assess spatial and seasonal variability in a culture-independent framework. Three different microarrays (the WIDE Life Detector Chip (WIDE LDChip), targeting broad microbial diversity; the psychrophile-Chip (PSYCHRO), focusing on psychrophilic bacteria; and the CYANOCHIP (CYANO), targeting cyanobacteria) were used. Distinct seasonal patterns emerged, with the WIDE LDChip revealing greater immunodetection diversity in July, although signal intensities were often higher in May. Psychrophilic microorganisms exhibited stronger and more diverse responses in spring, consistent with their adaptation to low temperatures. Cyanobacteria showed limited diversity but increased metabolic intensity during summer. Marked spatial heterogeneity was detected, with riverine stations displaying stronger overall reactivity, particularly in July; diversity indices (Shannon, Margalef, Simpson) confirmed significant spatial and seasonal changes in functional profiles. Overall, these findings highlight the influence of environmental gradients and seasonal transitions on the immunological profiles and functional guild composition of benthic microbial communities in Arctic rivers; they underscore their key role in regional biogeochemical cycles, demonstrating the effectiveness of multiplex microarray immunoassays for rapid detection of microbial biosignatures and for monitoring ecosystem function under natural and anthropogenic pressures in polar environments.