Water Mass Controlled Vertical Stratification of Bacterial and Archaeal Communities in the Western Arctic Ocean During Summer Sea-Ice Melting

• Published in: Microbial ecology 2023-05, Vol.85 (4), p.1150-1163
• Main Authors: Vipindas, Puthiya Veettil, Venkatachalam, Siddarthan, Jabir, Thajudeen, Yang, Eun Jin, Cho, Kyoung-Ho, Jung, Jinyoung, Lee, Youngju, Krishnan, Kottekkatu Padinchati
• Format: Article
• Language: English
• Subjects: Ammonium; Ammonium compounds; Archaea - genetics; Arctic Regions; Bacteria; Bacteria - genetics; Biomedical and Life Sciences; Biosphere; Chemical analysis; Chlorophyll; Chlorophylls; Climate change; Deep water; Distribution; Ecology; Environmental factors; Geoecology/Natural Processes; Heterotrophic bacteria; Ice melting; Life Sciences; Melting; Microbial activity; Microbial Ecology; Microbiology; Microbiology of Aquatic Systems; Microorganisms; Mixed layer; Nature Conservation; Nutrient concentrations; Oceans and Seas; Ponds; Sea ice; Sea surface; Seawater; Seawater - microbiology; Stratification; Stratified water; Summer; Surface mixed layer; Surface water; Surface water masses; Tracking; Vertical distribution; Water; Water analysis; Water circulation; Water column; Water depth; Water masses; Water Quality/Water Pollution; Water stratification
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/s00248-022-01992-z

The environmental variations and their interactions with the biosphere are vital in the Arctic Ocean during the summer sea-ice melting period in the current scenario of climate change. Hence, we analysed the vertical distribution of bacterial and archaeal communities in the western Arctic Ocean from sea surface melt-ponds to deep water up to a 3040 m depth. The distribution of microbial communities showed a clear stratification with significant differences among different water depths, and the water masses in the Arctic Ocean – surface mixed layer, Atlantic water mass and deep Arctic water – appeared as a major factor explaining their distribution in the water column. A total of 34 bacterial phyla were detected in the seawater and 10 bacterial phyla in melt-ponds. Proteobacteria was the dominant phyla in the seawater irrespective of depth, whereas Bacteroidota was the dominant phyla in the melt-ponds. A fast expectation-maximization microbial source tracking analysis revealed that only limited dispersion of the bacterial community was possible across the stratified water column. The surface water mass contributed 21% of the microbial community to the deep chlorophyll maximum (DCM), while the DCM waters contributed only 3% of the microbial communities to the deeper water masses. Atlantic water mass contributed 37% to the microbial community of the deep Arctic water. Oligotrophic heterotrophic bacteria were dominant in the melt-ponds and surface waters, whereas chemoautotrophic and mixotrophic bacterial and archaeal communities were abundant in deeper waters. Chlorophyll and ammonium were the major environmental factors that determined the surface microbial communities, whereas inorganic nutrient concentrations controlled the deep-water communities.