scholarly journals Denitrification in the water column of the central Baltic Sea

2013 ◽  
Vol 106 ◽  
pp. 247-260 ◽  
Author(s):  
Tage Dalsgaard ◽  
Loreto De Brabandere ◽  
Per O.J. Hall
Keyword(s):  
Baltic Sea ◽  
Water Column

scholarly journals Bacteriohopanepolyols record stratification, nitrogen fixation and other biogeochemical perturbations in Holocene sediments of the central Baltic Sea

2013 ◽  
Vol 10 (4) ◽  
pp. 2725-2735 ◽  
Author(s):  
M. Blumenberg ◽  
C. Berndmeyer ◽  
M. Moros ◽  
M. Muschalla ◽  
O. Schmale ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Stable Stratification ◽  
The Baltic Sea ◽  
Allochthonous Input ◽  
The North ◽  
Water Column Stratification ◽  
Gotland Deep ◽  
History Of ◽  
The Baltic

Abstract. The Baltic Sea, one of the world's largest brackish-marine basins, established after deglaciation of Scandinavia about 17 000 to 15 000 yr ago. In the changeable history of the Baltic Sea, the initial freshwater system was connected to the North Sea about 8000 yr ago and the modern brackish-marine setting (Littorina Sea) was established. Today, a relatively stable stratification has developed in the water column of the deep basins due to salinity differences. Stratification is only occasionally interrupted by mixing events, and it controls nutrient availability and growth of specifically adapted microorganisms and algae. We studied bacteriohopanepolyols (BHPs), lipids of specific bacterial groups, in a sediment core from the central Baltic Sea (Gotland Deep) and found considerable differences between the distinct stages of the Baltic Sea's history. Some individual BHP structures indicate contributions from as yet unknown redoxcline-specific bacteria (bacteriohopanetetrol isomer), methanotrophic bacteria (35-aminobacteriohopanetetrol), cyanobacteria (bacteriohopanetetrol cyclitol ether isomer) and from soil bacteria (adenosylhopane) through allochthonous input after the Littorina transgression, whereas the origin of other BHPs in the core has still to be identified. Notably high BHP abundances were observed in the deposits of the brackish-marine Littorina phase, particularly in laminated sediment layers. Because these sediments record periods of stable water column stratification, bacteria specifically adapted to these conditions may account for the high portions of BHPs. An additional and/or accompanying source may be nitrogen-fixing (cyano)bacteria, which is indicated by a positive correlation of BHP abundances with Corg and δ15N.

scholarly journals Near-Bottom Hypoxia Impacts Dynamics of Bacterioplankton Assemblage throughout Water Column of the Gulf of Finland (Baltic Sea)

PLoS ONE ◽  
2016 ◽  
Vol 11 (5) ◽  
pp. e0156147 ◽  
Author(s):  
Peeter Laas ◽  
Elina Šatova ◽  
Inga Lips ◽  
Urmas Lips ◽  
Jaak Simm ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Gulf Of Finland ◽  
Bottom Hypoxia ◽  
The Gulf Of Finland

scholarly journals Genomic Variations Underlying Speciation and Niche Specialization of Shewanella baltica

mSystems ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Jie Deng ◽  
Jennifer M. Auchtung ◽  
Konstantinos T. Konstantinidis ◽  
Ingrid Brettar ◽  
Manfred G. Höfle ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Transition Zone ◽  
Anaerobic Respiration ◽  
Electron Acceptors ◽  
Gene Content ◽  
Content Type ◽  
Genomic Variations ◽  
Niche Specialization ◽  
Shewanella Baltica

ABSTRACT Shewanella baltica was the dominant culturable nitrate-reducing bacterium in the eutrophic and strongly stratified Baltic Sea in the 1980s, where it primarily inhabited the oxic-anoxic transition zone. The genomic structures of 46 of these isolates were investigated through comparative genomic hybridization (CGH), which revealed a gradient of genomic similarity, ranging from 65% to as high as 99%. The core genome of the S. baltica species was enriched in anaerobic respiration-associated genes. Auxiliary genes, most of which locate within a few genomic islands (GIs), were nonuniformly distributed among the isolates. Specifically, hypothetical and mobile genetic element (MGE)-associated genes dominated intraclade gene content differences, whereas gain/loss of functional genes drove gene content differences among less related strains. Among the major S. baltica clades, gene signatures related to specific redox-driven and spatial niches within the water column were identified. For instance, genes involved in anaerobic respiration of sulfur compounds may provide key adaptive advantages for clade A strains in anoxic waters where sulfur-containing electron acceptors are present. Genes involved in cell motility, in particular, a secondary flagellar biosynthesis system, may be associated with the free-living lifestyle by clade E strains. Collectively, this study revealed characteristics of genome variations present in the water column and active speciation of S. baltica strains, driven by niche partitioning and horizontal gene transfer (HGT). IMPORTANCE Speciation in nature is a fundamental process driving the formation of the vast microbial diversity on Earth. In the central Baltic Sea, the long-term stratification of water led to formation of a large-scale vertical redoxcline that provided a gradient of environmental niches with respect to the availability of electron acceptors and donors. The region was home to Shewanella baltica populations, which composed the dominant culturable nitrate-reducing bacteria, particularly in the oxic-anoxic transition zone. Using the collection of S. baltica isolates as a model system, genomic variations showed contrasting gene-sharing patterns within versus among S. baltica clades and revealed genomic signatures of S. baltica clades related to redox niche specialization as well as particle association. This study provides important insights into genomic mechanisms underlying bacterial speciation within this unique natural redoxcline.

scholarly journals Hypoxia and nitrogen processing in the Baltic Sea water column

2012 ◽  
Vol 57 (1) ◽  
pp. 325-337 ◽  
Author(s):  
Susanna Hietanen ◽  
Helena Jäntti ◽  
Christo Buizert ◽  
Klaus Jürgens ◽  
Matthias Labrenz ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Sea Water ◽  
The Baltic Sea ◽  
The Baltic

Seasonal variation of methane in the water column of Arkona and Bornholm Basin, western Baltic Sea

2014 ◽  
Vol 139 ◽  
pp. 332-347 ◽  
Author(s):  
W. Gülzow ◽  
U. Gräwe ◽  
S. Kedzior ◽  
O. Schmale ◽  
G. Rehder
Keyword(s):  
Seasonal Variation ◽  
Baltic Sea ◽  
Water Column ◽  
Bornholm Basin

scholarly journals Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

2013 ◽  
Vol 10 (1) ◽  
pp. 681-709 ◽  
Author(s):  
K. Dähnke ◽  
B. Thamdrup
Keyword(s):  
Baltic Sea ◽  
Water Column ◽  
Isotope Fractionation ◽  
Isotope Effects ◽  
Nitrogen Isotope ◽  
Current View ◽  
Underlying Assumption ◽  
Stable Isotope Fractionation ◽  
Seasonal Hypoxia ◽  
Preferential Uptake

Abstract. The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15N-isotope value (δ15N) to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes responsible for approximately one third of global nitrogen removal, have little to no isotope effect on nitrate in the water column. We investigated the isotope fractionation in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, Northern Germany), a site with seasonal hypoxia and dynamic nitrogen turnover. We found tremendously high denitrification rates, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 18.9‰ for nitrogen and 15.8‰ for oxygen in nitrate. While the input of nitrate to the water column remains speculative, these results challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculations may need to consider this variability, as both preferential uptake of light nitrate and release of the remaining heavy fraction can significantly alter water column nitrate isotope vales at the sediment-water interface.

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