The pelagic system

Smetacek, Victor; Bodungen, Bodo von; Bölter, Manfred; Bröckel, Klaus von; Dawson, R.; Knoppers, Bastiaan A.; Liebezeit, Gerd; Martens, Peter; Peinert, P.; Pollehne, Falk; Stegmann, P.; Wolter, K.; Zeitschel, B.

doi:10.1029/ln013p0032

Cited by 6 publications

(3 citation statements)

References 182 publications

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“…7b), which may affect local productivity patterns as studies in other shallow ecosystems indicate (Rozan et al, 2002). The feedbacks on primary production and the timing of the autumn bloom in Boknis Eck by benthic P release are suspected to be important but have not been investigated quantitatively (Smetacek et al, 1987).…”

Section: Iron and Phosphorus Remobilization And Fluxesmentioning

confidence: 99%

Modeling benthic–pelagic nutrient exchange processes and porewater distributions in a seasonally hypoxic sediment: evidence for massive phosphate release by <i>Beggiatoa</i>?

et al. 2013

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Abstract. This study presents benthic data from 12 samplings from February to December 2010 in a 28 m deep channel in the southwest Baltic Sea. In winter, the distribution of solutes in the porewater was strongly modulated by bioirrigation which efficiently flushed the upper 10 cm of sediment, leading to concentrations which varied little from bottom water values. Solute pumping by bioirrigation fell sharply in the summer as the bottom waters became severely hypoxic (< 2 μM O2). At this point the giant sulfide-oxidizing bacteria Beggiatoa was visible on surface sediments. Despite an increase in O2 following mixing of the water column in November, macrofauna remained absent until the end of the sampling. Contrary to expectations, metabolites such as dissolved inorganic carbon, ammonium and hydrogen sulfide did not accumulate in the upper 10 cm during the hypoxic period when bioirrigation was absent, but instead tended toward bottom water values. This was taken as evidence for episodic bubbling of methane gas out of the sediment acting as an abiogenic irrigation process. Porewater–seawater mixing by escaping bubbles provides a pathway for enhanced nutrient release to the bottom water and may exacerbate the feedback with hypoxia. Subsurface dissolved phosphate (TPO4) peaks in excess of 400 μM developed in autumn, resulting in a very large diffusive TPO4 flux to the water column of 0.7 ± 0.2 mmol m−2 d−1. The model was not able to simulate this TPO4 source as release of iron-bound P (Fe–P) or organic P. As an alternative hypothesis, the TPO4 peak was reproduced using new kinetic expressions that allow Beggiatoa to take up porewater TPO4 and accumulate an intracellular P pool during periods with oxic bottom waters. TPO4 is then released during hypoxia, as previous published results with sulfide-oxidizing bacteria indicate. The TPO4 added to the porewater over the year by organic P and Fe–P is recycled through Beggiatoa, meaning that no additional source of TPO4 is needed to explain the TPO4 peak. Further experimental studies are needed to strengthen this conclusion and rule out Fe–P and organic P as candidate sources of ephemeral TPO4 release. A measured C/P ratio of < 20 for the diffusive flux to the water column during hypoxia directly demonstrates preferential release of P relative to C under oxygen-deficient bottom waters. This coincides with a strong decrease in dissolved inorganic N/P ratios in the water column to ~ 1. Our results suggest that sulfide oxidizing bacteria could act as phosphorus capacitors in systems with oscillating redox conditions, releasing massive amounts of TPO4 in a short space of time and dramatically increasing the internal loading of TPO4 to the overlying water.

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Section: Iron and Phosphorus Remobilization And Fluxesmentioning

confidence: 99%

Modeling benthic–pelagic nutrient exchange processes and porewater distributions in a seasonally hypoxic sediment: evidence for massive phosphate release by <i>Beggiatoa</i>?

et al. 2013

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“…This amplifies annual recurrence by more or less severe phytoplankton blooms and the subsequent oxygen consumption in bottom waters (Rachor 1980(Rachor , 1982Rachor & Albrecht 1983;Steimle & Sindermann 1978;Swanson & Sindermann 1979;Meyer-Reil et al 1987). The onset of phytoplankton blooms begins in the North Sea in April to May (Steif 1988), in the Baltic Sea in March to April (Smetacek et al 1987). The blooms coincide with warming of the surface waters and with establishment of a temperature stratified water column.…”

Section: Dynamics Of Modern Shelf and Epicontinental Sea Anoxiamentioning

confidence: 99%

“…The blooms coincide with warming of the surface waters and with establishment of a temperature stratified water column. Duration of the blooms lasts from several weeks to several months (Smetacek et al 1987;Steif 1988), but depends largely on the persistence of warm and calm weather. In the North Sea, like in most temperate waters, diatoms dominate during early bloom stages (April and May) and may reach more than 70% of plankton biomass (Steif 1988).…”

Section: Dynamics Of Modern Shelf and Epicontinental Sea Anoxiamentioning

confidence: 99%

Distribution, dynamics and palaeoecology of Kimmeridgian (Upper Jurassic) shelf anoxia in western Europe

Oschmann

1991

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Facies and related macrobenthic associations in the Kimmeridgian epeiric basin in Western Europe are arranged along an onshore-offshore gradient. It ranges from an intermediate-to-high-energy nearshore zone to a low-energy oxygen-controlled offshore environment.Anoxia in the Kimmeridgian epeiric basin was not a permanent feature and cannot be described by the classical models which define aerobic, dysaerobic and anaerobic facies zones. These models have been proposed for deep (slope and basin) environments, in which the oxygen values at a certain depth remain in general constant. In contrast, anoxia in the Kimmeridgian is more dynamic and resembles modern anoxia occurring in eutrophic shelf and epeiric basins (e.g. the coastal areas of Mid-Atlantic Bight, North Sea and Baltic Sea) and exhibit remarkable annual oxygen fluctuations.Therefore, in contrast to the classical models, a modified oxygen zonation for shelf environments is introduced, in order to explain the palaeoenvironment and dynamic alternation of Kimmeridgian anoxia. Both end members, the aerobic and the anaerobic environment, do occur as well. However, the short-term fluctuations prevent establishment of the dysaerobic zone. Instead, there is a seasonal anaerobic to anoxic environment, here defined as poikiloaerobic zone, which is colonized only by a few opportunists.

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Growth Rates, Age Determination, and Calcification Levels in Flustra foliacea (L.) (Bryozoa: Cheilostomata): Preliminary Assessment

Fortunato

Schäfer

Blaschek

2012

Lecture Notes in Earth System Sciences

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The pelagic system

Cited by 6 publications

References 182 publications

Modeling benthic–pelagic nutrient exchange processes and porewater distributions in a seasonally hypoxic sediment: evidence for massive phosphate release by <i>Beggiatoa</i>?

Modeling benthic–pelagic nutrient exchange processes and porewater distributions in a seasonally hypoxic sediment: evidence for massive phosphate release by <i>Beggiatoa</i>?

Distribution, dynamics and palaeoecology of Kimmeridgian (Upper Jurassic) shelf anoxia in western Europe

Growth Rates, Age Determination, and Calcification Levels in Flustra foliacea (L.) (Bryozoa: Cheilostomata): Preliminary Assessment

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The pelagic system

Cited by 6 publications

References 182 publications

Modeling benthic–pelagic nutrient exchange processes and porewater distributions in a seasonally hypoxic sediment: evidence for massive phosphate release by &lt;i&gt;Beggiatoa&lt;/i&gt;?

Modeling benthic–pelagic nutrient exchange processes and porewater distributions in a seasonally hypoxic sediment: evidence for massive phosphate release by &lt;i&gt;Beggiatoa&lt;/i&gt;?

Distribution, dynamics and palaeoecology of Kimmeridgian (Upper Jurassic) shelf anoxia in western Europe

Growth Rates, Age Determination, and Calcification Levels in Flustra foliacea (L.) (Bryozoa: Cheilostomata): Preliminary Assessment

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Modeling benthic–pelagic nutrient exchange processes and porewater distributions in a seasonally hypoxic sediment: evidence for massive phosphate release by <i>Beggiatoa</i>?

Modeling benthic–pelagic nutrient exchange processes and porewater distributions in a seasonally hypoxic sediment: evidence for massive phosphate release by <i>Beggiatoa</i>?