The Seasonal Modulation of Organic Matter Utilization by Bacteria in the Danube–Black Sea Mixing Zone

Becquevort, Sylvie; Bouvier, Thierry; Lancelot, Christiane; Cauwet, Gustave; Deliat, Gaëlle; Егоров, В. Н.; Поповичев, В. Н.

doi:10.1006/ecss.2000.0651

Cited by 43 publications

(14 citation statements)

References 67 publications

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“…The latter value is in agreement with the observation by Raymond and Bauer (2000) who reported that 10 % of the DOC exported from the York river estuary within the mid-Atlantic Bight was labile. In the same sense, the biodegradable fraction of DOC in the range of 10-15 % has been reported previously in several other coastal areas (Deliat, 2001;Becquevort et al, 2002).…”

Section: Discussionsupporting

confidence: 56%

Organic carbon and bacterial heterotrophic activity in the maximum turbidity zone of the Seine estuary (France)

Servais

Garnier

2006

Aquat. Sci.

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The aim of this study is to understand the sources, biodegradability and fate of organic carbon entering the maximum turbidity zone (MTZ) of the Seine estuary. Dissolved (DOC) and particulate organic matter (POC), and their biodegradable fractions (BDOC and BPOC) were investigated immediately upstream and within the MTZ in various hydrological conditions together with bacterial production of free-living and particle-associated cells. At the entrance of the MTZ, average DOC was 3.6 mg C l -1 with a biodegradable fraction of 23 %. The DOC and BDOC/DOC ratio decreased linearly with increasing salinity, indicating a dilution of river freshwater with a higher DOC and higher BDOC/DOC ratio than marine waters. The organic content of suspended matter (SM) at the entrance of the MTZ was high (POC/SM ratios up to 10.6 %), especially during phytoplankton blooms when high BPOC/POC ratios were also found. Within the MTZ, the carbon content of SM was lower and less variable; the biodegradable fraction of POC in the MTZ was lower than upstream, illustrating the progressive bacterial degradation of BPOC within the MTZ. Total bacterial production in the MTZ fl uctuated between 0.2 and 5.1 µg C l -1 h -1 ; average production of free-living bacteria was 0.77 µg C l -1 h -1 while that of attached bacteria was 1.47 µg C g SM -1 h -1 . Growth rates of attached bacteria were, on average, three times higher than those of free-living ones. Bacterial activity can explain the decrease in the POC/SM ratio observed between summer and fall in the MTZ.

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Section: Discussionsupporting

confidence: 56%

Organic carbon and bacterial heterotrophic activity in the maximum turbidity zone of the Seine estuary (France)

Servais

Garnier

2006

Aquat. Sci.

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“…Based on the most recent Black Sea DOC data available [Ducklow et al, 2007], we estimate the mean annual concentration of DOM in riverine waters to be 222 uM C, virtually all of which is recalcitrant. Observations of total DOC concentrations at the Danube mouth were reported between 192 and 375 mM [Becquevort et al, 2002;Saliot et al, 2002], consistent with our estimate above.…”

Section: Boundary Conditionssupporting

confidence: 92%

Validation of an intermediate‐complexity model for simulating marine biogeochemistry under anoxic conditions in the modern Black Sea

Romaniello¹,

Derry

2010

Geochem Geophys Geosyst

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[1] We test the ability of a new 1-D intermediate-complexity box model (ICBM) that includes process-based C, N, P, O, and S biogeochemistry to simulate profiles and fluxes of biogeochemically reactive species across a wide range of ocean redox states. The ICBM was developed to simulate whole ocean processes for paleoceanographic applications and has been tested with data from the modern global ocean. Here we adapt the circulation submodel of the ICBM to simulate water mass exchange and eddy diffusion processes in the Black Sea but make only very minor changes to the biogeochemical submodel. We force the model with estimated natural and anthropogenic inputs of tracers and nutrients to the Black Sea and compare the results of the simulations to modern observations. Ventilation of the Black Sea is modeled by depth-dependent entrainment of Cold Intermediate Layer water into Bosphorus plume water and subsequent intrusion into deep layers. The simulated profiles of circulation tracers , salinity, CFC-12, and radiocarbon agree well with available data, suggesting that the model does a reasonable job of representing physical exchange. Vertical profiles of biogeochemically active components are in good overall agreement with observations. The lack of trace metal (Mn and Fe) cycling in the model results in some discrepancies between the simulated profiles and observation across the suboxic zone; however, the overall redox balance is not sensitive to this difference. We compare modeled basin-wide biogeochemical fluxes to available estimates, but in a number of cases uncertainties in modern budgets limit our ability to test the model rigorously. In agreement with earlier work we find that fixed N losses via thiodenitrification are likely a major pathway in the Black Sea N cycle. Overall, the same biogeochemical submodel used to simulate the modern global ocean appears to perform well in simulating Black Sea processes without requiring significant modification. The ability of a single model to perform across a wide range of redox states is an important prerequisite for applying the ICBM to deep time paleoceanographic problems. The model source code is available as MATLAB ™ 7 m-files provided as auxiliary material.

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“…Harris et al (2001) applied a growth efficiency of 40% to a large data set in the oligotrophic western Mediterranean Sea. Recently, Becquevort et al (2002) reported a growth yield of 23% as estimated from bioassays performed in the Danube-Black Sea mixing zone. Using a medium BGE of 30% (e.g.…”

Section: Doc Sourcesmentioning

confidence: 99%

“…While the biodegradable fraction of Po-derived DOC has not been determined, this fraction in other riverine DOC has been estimated to be on the order of 10 to 20% (Søndergaard & Middelboe 1995, Becquevort et al 2002. Whatever the mechanism of its production, the accumulation of slow-to-degrade DOC during the high-primary-productivity season is a common feature of many marine systems (e.g.…”

Section: Introductionmentioning

confidence: 99%

Major inter-annual variations in microbial dynamics in the Gulf of Trieste (northern Adriatic Sea) and their ecosystem implications

Umani¹,

Negro²,

Larato³

et al. 2007

Aquat. Microb. Ecol.

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The Seasonal Modulation of Organic Matter Utilization by Bacteria in the Danube–Black Sea Mixing Zone

Cited by 43 publications

References 67 publications

Organic carbon and bacterial heterotrophic activity in the maximum turbidity zone of the Seine estuary (France)

Organic carbon and bacterial heterotrophic activity in the maximum turbidity zone of the Seine estuary (France)

Validation of an intermediate‐complexity model for simulating marine biogeochemistry under anoxic conditions in the modern Black Sea

Major inter-annual variations in microbial dynamics in the Gulf of Trieste (northern Adriatic Sea) and their ecosystem implications

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