Oxic, suboxic, and anoxic conditions in the Black Sea

Stewart, Keith; Kassakian, Steven Z.; Krynytzky, Marta; DiJulio, Doug; Murray, James

doi:10.1007/978-1-4020-5302-3_1

Cited by 22 publications

(15 citation statements)

References 51 publications

(46 reference statements)

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“…The presence of marker pigments for photosynthetic sulfur bacteria (that is, isorenieratene and okenone) have been often reported as evidence of euxinic conditions in ancient oceans ( Damsté and Köster, 1998 ; Brocks et al, 2005 ). These conditions are not common nowadays, although persistent euxinia can be found in deep silled basins such as the Black Sea, Baltic Sea and Cariaco Basin ( Millero, 1991 ; Stewart et al, 2007 ). Future climate change scenarios predict, however, an increasing of euxinia phenomena, mainly in coastal marine ecosystems ( Diaz and Rosenberg, 2008 ).…”

Section: Discussionmentioning

confidence: 99%

Connecting biodiversity and potential functional role in modern euxinic environments by microbial metagenomics

et al. 2015

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Stratified sulfurous lakes are appropriate environments for studying the links between composition and functionality in microbial communities and are potentially modern analogs of anoxic conditions prevailing in the ancient ocean. We explored these aspects in the Lake Banyoles karstic area (NE Spain) through metagenomics and in silico reconstruction of carbon, nitrogen and sulfur metabolic pathways that were tightly coupled through a few bacterial groups. The potential for nitrogen fixation and denitrification was detected in both autotrophs and heterotrophs, with a major role for nitrogen and carbon fixations in Chlorobiaceae. Campylobacterales accounted for a large percentage of denitrification genes, while Gallionellales were putatively involved in denitrification, iron oxidation and carbon fixation and may have a major role in the biogeochemistry of the iron cycle. Bacteroidales were also abundant and showed potential for dissimilatory nitrate reduction to ammonium. The very low abundance of genes for nitrification, the minor presence of anammox genes, the high potential for nitrogen fixation and mineralization and the potential for chemotrophic CO2 fixation and CO oxidation all provide potential clues on the anoxic zones functioning. We observed higher gene abundance of ammonia-oxidizing bacteria than ammonia-oxidizing archaea that may have a geochemical and evolutionary link related to the dominance of Fe in these environments. Overall, these results offer a more detailed perspective on the microbial ecology of anoxic environments and may help to develop new geochemical proxies to infer biology and chemistry interactions in ancient ecosystems.

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Section: Discussionmentioning

confidence: 99%

Connecting biodiversity and potential functional role in modern euxinic environments by microbial metagenomics

et al. 2015

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“…A permanent pycnocline in about 100-150m water depth prevents vertical exchange of water masses and deep-water ventilation. A pelagic redoxcline in this depth interval separates oxic surface water from sulphidic water favouring sapropel formation (Murray, 1900;Repeta et al, 1989;Özsoy and Ünlüata, 1997;Murray et al, 2007;Dellwig et al, 2010). With a maximum depth of about 2200m, the Black Sea represents the largest brackish and sulphidic water body on Earth (Demaison and Moore, 1980;Özsoy and Ünlüata, 1997).…”

Section: Climate and Environmental Setting Of The Black Sea Regionmentioning

confidence: 99%

Major hydrological shifts in the Black Sea “Lake” in response to ice sheet collapses during MIS 6 (130–184 ka BP)

Wegwerth

Dellwig

Wulf

et al. 2019

Quaternary Science Reviews

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Black Sea "Lake" record between 184 ka BP and 124 ka BP (MIS 6-5e) is presented.• Main parameters are δ 18 O, 87 Sr/ 86 Sr, Sr/Ca, and Mg/Ca of ostracods.• Higher temperatures and stadial-interstadial variability during early MIS 6.• Three long-term meltwater periods during insolation maxima and retreated ice sheets.• Caspian-Black Sea connection during meltwater periods, but different sources/pathways.

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“…Hypoxic environments are characterized by the depletion of oxygen with some demonstrating elevated concentrations of sulfides (Stewart et al ., ). Sulfide production can result from sulfate reduction coupled to the oxidation of reduced carbon compounds such as methane (Stewart et al ., ) or through the oxidation of organic matter where sulfate is used as the electron acceptor rather than oxygen (Fenchel et al ., ). Oxygen is the most thermodynamically favoured terminal electron acceptor followed by nitrate, nitrite then sulfate and finally carbon dioxide (Wright et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Marine bacterioplankton community turnover within seasonally hypoxic waters of a subtropical sound: Devil's Hole, Bermuda

Parsons

Nelson

Carlson

et al. 2014

Environmental Microbiology

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Understanding bacterioplankton community dynamics in coastal hypoxic environments is relevant to global biogeochemistry because coastal hypoxia is increasing worldwide. The temporal dynamics of bacterioplankton communities were analysed throughout the illuminated water column of Devil's Hole, Bermuda during the 6-week annual transition from a strongly stratified water column with suboxic and high-pCO2 bottom waters to a fully mixed and ventilated state during 2008. A suite of culture-independent methods provided a quantitative spatiotemporal characterization of bacterioplankton community changes, including both direct counts and rRNA gene sequencing. During stratification, the surface waters were dominated by the SAR11 clade of Alphaproteobacteria and the cyanobacterium Synechococcus. In the suboxic bottom waters, cells from the order Chlorobiales prevailed, with gene sequences indicating members of the genera Chlorobium and Prosthecochloris--anoxygenic photoautotrophs that utilize sulfide as a source of electrons for photosynthesis. Transitional zones of hypoxia also exhibited elevated levels of methane- and sulfur-oxidizing bacteria relative to the overlying waters. The abundance of both Thaumarcheota and Euryarcheota were elevated in the suboxic bottom waters (> 10(9) cells l(-1)). Following convective mixing, the entire water column returned to a community typical of oxygenated waters, with Euryarcheota only averaging 5% of cells, and Chlorobiales and Thaumarcheota absent.

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Oxic, suboxic, and anoxic conditions in the Black Sea

Cited by 22 publications

References 51 publications

Connecting biodiversity and potential functional role in modern euxinic environments by microbial metagenomics

Connecting biodiversity and potential functional role in modern euxinic environments by microbial metagenomics

Major hydrological shifts in the Black Sea “Lake” in response to ice sheet collapses during MIS 6 (130–184 ka BP)

Marine bacterioplankton community turnover within seasonally hypoxic waters of a subtropical sound: Devil's Hole, Bermuda

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