Abstract
Based on a three-year study on the prokaryotic community composition in peat bog lakes surrounded by a floating mat of Sphagnum sp. moss in the conditions of Northeast Poland (Central Europe), we verified the relationship between 20 water parameters and main Eubacteria and Archaea phyla for specific sites: the subsurface (pelagic zone), near-bottom (benthic zone), and the Sphagnum mat (ecotone zone). Abundance and composition of the main aquatic bacteria phyla (Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Actinobacteria, and Cytophaga-Flavobacteria) and Archaea were associated with different combinations of physico-chemical parameters of water, and followed temporal variations of temperature, dissolved organic carbon (DOC), aromaticity, and water color. Redundancy analysis (RDA) showed that water acidity is a less significant predictor of bacterial activity; however, we have found Betaproteobacteria negatively correlated (r = −0.49, p = 0.01), while Actinobacteria positively correlated (r = 0.21, p = 0.05) to pH. This relation was the most significant in the ecotone zone. In the overall bacteria community structure Betaproteobacteria dominated (18.3%) regardless of site or season, except for winter when, at low temperatures and DOC concentrations, Actinobacteria increased to 22.9%. The Archaea fraction was uniform (11%) in seasons and sites and showed no specific preferences to physico-chemical predictors. Although the water parameters from the Sphagnum mat did not differ significantly from pelagic water, its role as a source of allochthonous organic matter is crucial for bacteria activity. The relations between peat bog lake attributes and seasonal changes in bacterial diversity demonstrated a distinct divergent pattern for each prokaryote. Obtaining results will provide support for any future evaluation of the effects of environmental variables on prokaryotic community structures in peat bog lakes.
Highlights
Peat bog lakes, usually surrounded by Sphagnum-dominated peatland, create one of the most extensive types of wetlands in the temperate climate zone, characterized by high acidity, water color, and lower concentrations of mineral compounds, but higher concentration of organic matter when compared to eutrophic or oligotrophic lakes [1]
To other types of freshwater ecosystems, microorganisms play a fundamental role in the decomposition of organic matter and system respiration and, they recycle nutrients in a complex manner involved in various geochemical cycles as the nitrogen, phosphorus, and carbon cycles [2]
Betaproteobacteria dominated regardless of a site or season, except for winter, when the share of Actinobacteria increased to 22.9%
Summary
Usually surrounded by Sphagnum-dominated peatland, create one of the most extensive types of wetlands in the temperate climate zone, characterized by high acidity, water color, and lower concentrations of mineral compounds, but higher concentration of organic matter when compared to eutrophic or oligotrophic lakes [1]. These ombrotrophic ecosystems are decoupled from groundwater of the surrounding watershed and receive all water and nutrient inputs from the atmosphere. The unique feature of the humic lakes is the limited availability of nutrients, what makes other factors significant in the regulation of bacterial community composition (BCC), for example, the binding of metals and organic compounds affects their bioavailability and natural acidity [4]
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