Climate warming-driven changes in the flux of dissolved organic matter and its effects on bacterial communities in the Arctic Ocean: A review

Abstract

The warming of the Arctic Ocean impacts the dissolved organic matter (DOM) imports into the Arctic region, which affects the local bacterial communities. This review addressed the current status of DOM inputs and their potential influences on bacteria data (e.g., population, production, and metabolic activity of bacteria), as well as the projected changes of DOM inputs and bacterial communities as a result of climate warming. Microbial communities are likely affected by the warming climate and the transport of DOM to the Arctic Ocean. Imported DOM can alter Arctic bacterial abundance, cell size, metabolism, and composition. DOM fluxes from Arctic River runoff and adjacent oceans have been enhanced, with warming increasing the contribution of many emerging DOM sources, such as phytoplankton production, melted sea ice, thawed permafrost soil, thawed subsea permafrost, melted glaciers/ice sheets, atmospheric deposition, groundwater discharge, and sediment efflux. Imported DOM contains both allochthonous and autochthonous components; a large quantity of labile DOM comes from emerging sources. As a result, the Arctic sea water DOM composition is transformed to include a wider range of various organic constituents such as carbohydrates (i.e., glucose), proteinaceous compounds (i.e., amino acid and protein-like components) and those with terrigenous origins (i.e., humic-like components). Changes to DOM imports can alter Arctic bacterial abundance, cell size, metabolism, and composition. Under current global warming projections, increased inflow of DOM and more diverse DOM composition would eventually lead to enhanced CO2 emissions and frequent emergence of replacement bacterial communities in the Arctic Ocean. Understanding the changes in DOM fluxes and responses of bacteria in the Arctic broadens our current knowledge of the Arctic Ocean’s responses to global warming.

The Arctic summer microbiome across Fram Strait: Depth, longitude, and substrate concentrations structure microbial diversity in the euphotic zone

“…ASVs predominantly correlated with DOC, amines, and sugar acids in the western Fram Strait compared to temperature and CHO in the eastern Fram Strait, with ASVs being associated with different bacterial families (Figure 5). Such trends are probably connected with phytoplankton distribution, which varies between eastern and western Fram Strait (Nöthig et al, 2015). Accordingly, analysis of chl-a concentrations in different size fractions indicated the prevalence of smaller phytoplankton (0.4-3 μm fraction) in eastern Fram Strait (Figure S5), in agreement with previous findings (Kilias et al, 2014;Metfies et al, 2016).…”

“…Bulk DOC concentrations were 12% higher in the western Fram Strait (Wilcoxon rank‐sum test, p < 0.05; Figure 2B). Presumably, this relates to higher concentrations of terrestrial‐ and ice‐derived DOC, which can constitute up to 30% of organic matter in Arctic waters (Nguyen et al, 2022; Opsahl et al, 1999). These patterns underscore that specific organic compounds prevail under Arctic versus Atlantic influence (Engel et al, 2019; Priest, Vidal‐Melgosa, et al, 2023; von Jackowski et al, 2020).…”

“…The concentrations of neutral carbohydrates (CHO), amino acids (AA), sugar acids, and amines peaked in the chl-max of the eastern Fram Strait (Wilcoxon ranksum test, p < 0.05), corresponding to elevated primary production (Nöthig et al, 2015) and availability of labile substrates (Piontek et al, 2014). Bulk DOC concentrations were 12% higher in the western Fram Strait (Wilcoxon rank-sum test, p < 0.05; Figure 2B).…”

“…The HAUSGARTEN/FRAM long-term observatory studies biological communities, benthopelagic coupling, and physical oceanography in the Fram Strait, the major gateway between the Atlantic and Arctic Oceans (Nöthig et al, 2015;Soltwedel et al, 2016). Here, polar water outflowing from the central Arctic Ocean via the East Greenland Current (EGC; western Fram Strait) meets Atlantic water flowing northward via the West Spitsbergen Current (WSC; eastern Fram Strait).…”

Ecological Interaction between Bacteriophages and Bacteria in Sub-Arctic Kongsfjorden Bay, Svalbard, Norway

“…In the present study, Sulfitobacter profundi ( Alphaproteobacteria ) was the predominant bacterial taxon detected in June. Although this bacterium is globally distributed [ 48 ] and frequently appears in polar regions [ 49 ], Nguyen et al [ 50 ] reported that Sulfitobacter profundi is an opportunistic species and can also occur in oligotrophic environments. Moreover, Sulfitobacter pontiacus ( Alphaproteobacteria ) and Pseudoalteromonas sp.…”