The influence of shelfbreak forcing on the alongshelf penetration of the Danube buoyant water, Black sea

Yankovsky, Alexander E.; Lemeshko, E. M.; Ilyin, Y.P.

doi:10.1016/j.csr.2004.03.007

Cited by 20 publications

(16 citation statements)

References 25 publications

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“…They employed Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) data and a coupled biophysical model to show two prevailing patterns on the transport of nutrient‐rich, low‐salinity waters imported through the Danube delta: an along‐shelf distribution favoring coastal advection toward south (prevailing in winter) and an offshore tendency favoring northeastward distribution with the potential for reaching the basin interior (prevailing in summer). Yankovsky et al [2004] discussed the influence of the basin‐wide MRC on the southward advection of Danube waters. In addition, topographic features can influence the buoyancy‐driven coastal current, such as the convergence of isobaths around capes, which intensifies processes associated with water and sediment dispersal around coastal headlands [ Bastos et al , 2002, 2003].…”

Section: Regional Setting Of the Northwestern Black Seamentioning

confidence: 99%

“…Consequently, despite studies of particulate matter dynamics in the Danube‐influenced area in terms of particulate inputs of nutrients (mainly phosphorous) and pollutants (along with their biogeochemical implications) which adsorb strongly on particles [ Guieu et al , 1998; Tankéré et al , 2001; Guieu and Martin , 2002; Lancelot et al , 2002], there is a lack of information regarding the marginal dispersal patterns of river‐borne materials and their relation to hydrological features. Some studies on the physical characteristics of the Danube River plume and resulting circulation have been carried out by Kourafalou and Stanev [2001], Beckers et al [2002], Yankovsky et al [2004], and Kourafalou et al [2005].…”

Section: Introductionmentioning

confidence: 99%

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River‐induced particle distribution in the northwestern Black Sea (September 2002 and 2004)

Karageorgis¹,

Kourafalou²,

Anagnostou³

et al. 2009

J. Geophys. Res.

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[1] Observations from two comprehensive oceanographic surveys on the northwestern Black Sea are analyzed to reveal the hydrological characteristics of the shelf area around the Danube delta in relation to particulate matter dynamics. These processes have broader implications on flows through the adjacent complex strait system. The surveys cover both a period of high (September 2002) and low (September 2004) discharge of the Danube River. The resulting low-salinity waters generally occupied the upper 10-15 m within the 20-30 m thick warm layer that was separated by deeper cooler waters through a sharp thermocline. The buoyant plume was influenced by the discharge conditions and the prevailing wind patterns. The plume structure was identified using in situ bottle data, continuous beam transmission and fluorescence profiles, and satellite remotely sensed data. Particulate matter concentration values correlated with low-salinity riverine waters and their maxima were recorded in the immediate vicinity of the Danube branches, decreasing rapidly toward the open sea. The preferred particle transport pathway in 2002 was along a narrow strip near the coast, with a south-southwest direction, favored by the strong northeasterlies which predominated prior to the cruise. Low-salinity waters and riverine particles in 2004 were characterized by mostly offshore removal, attributed to calmer northwesterlies prior to the survey. Changes in ambient stratification due to wind-driven vertical displacements of the seasonal thermocline appeared to also influence the plume dynamics. The downwelling (upwelling) conditions that prevailed in 2002 (2004) were revealed in both the in situ vertical profile temperature measurements and the satellite-derived sea surface temperature patterns.

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Section: Regional Setting Of the Northwestern Black Seamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

River‐induced particle distribution in the northwestern Black Sea (September 2002 and 2004)

Karageorgis¹,

Kourafalou²,

Anagnostou³

et al. 2009

J. Geophys. Res.

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“…The Danube annually discharges 77% of the total river runoff to the Black Sea and 85% of the runoff entering the northwestern shelf. The resulting buoyant plume, augmented with freshwater by southward coastal current fed by the Nistru (Dniestr), Dniepr, and Southern Bug rivers, propagates onto the shelf and along the coast toward the southwest (Stanev et al, 2002;Yankovsky et al, 2004). The coastal plume further interacts with the western cyclonic gyre of the Rim Current, forming quasi-persistent anticyclonic eddies over the middle shelf ( Fig.…”

Section: Basin Characteristicsmentioning

confidence: 99%

“…The coastal plume further interacts with the western cyclonic gyre of the Rim Current, forming quasi-persistent anticyclonic eddies over the middle shelf ( Fig. 2; Oguz et al, 1993;Korotaev et al, 2003;Yankovsky et al, 2004). Via its plume, the quantity and quality of Danube water and suspended-sediment discharge exerts a strong influence on sedimentation, water-column and sediment chemistry, and ecosystems of the northwestern shelf of the Black Sea (Bacescu et al, 1971;Humborg et al, 1997;Lancelot et al, 2002 and papers therein).…”

Section: Basin Characteristicsmentioning

confidence: 99%

River Delta Morphodynamics: Examples from the Danube Delta

Giosan¹,

Donnelly²,

Vespremeanu³

et al. 2005

River Deltas-Concepts, Models, and Examples

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The Danube, with its mouths at the Black Sea, has been economically and strategically one of the most important rivers in Europe; consequently, its delta has been studied since the Nineteenth Century. Although many morphological and sedimentological aspects of the Danube delta are well understood, its late Quaternary evolution remains ambiguous. This uncertainty reflects in part the complexity of the sea-level variations and water-chemistry changes related to the periodic isolation of the Black Sea during eustatic lowstands, but also a lack of accurate age control of the deltaic deposits. On the basis of a review of existing radiocarbon dates, we propose that the development of the delta at the open coast started approximately 6,000-5,500 14 C years ago, much later than the 9,000 14 C years BP previously suggested. Morphodynamics of the open-coast Danube delta has been determined largely by the interaction between fluvial deposition and the strong southward wave-induced longshore transport. Morphological and facies asymmetry displayed by the marine lobes of the Danube delta indicate that a strong and sustained southward-directed longshore transport has been a persistent process along the delta shore. Coastal evolution on the adjacent nondeltaic coast is also strongly coupled to the delta morphodynamics via the longshore transport. Analysis of recent deltaic progradation of the youngest open-coast lobes of Danube delta indicates that river-mouth morphodynamics is highly nonlinear, involving multiple feedbacks between subaerial deltaic progradation, deposition on the subaqueous delta, current and wave hydrodynamics as well as wave-current interactions. First, a feedback loop is activated by the hydraulic groin effect of the river plume, which leads to a mutually sustained progradation of the updrift coast and subaqueous delta at the mouth. Second, the development of a shallow subaerial delta platform, strongly offset to the downdrift direction, helps dissipate waves reaching the platform, leading to entrapment of sediment on the platform. Third, increased flood-induced deposition on the subaqueous delta platform, followed by wave reworking, leads to recurrent emergence of barrier islands at its offshore edge; longshore transport is then channeled (i.e., intensified and guided) by the new coast along the barrier, leading to a rapid alongshore expansion of the subaqueous delta in the downdrift direction. Although the sedimentation processes are complex, the resulting morphology at the mouth exhibits a tendency to self-organize that is reflected and preserved by the facies architecture of wave-influenced lobes.

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“…1). This feature and mesoscale exchanges between the shelf and deep basin over the broad topographic slope zone (Korotaev et al 2003, Yankovsky et al 2004 reduce eutrophication southward. The shelf lying roughly north of ~45°N receives considerable fresh water and nutrient discharges from the Danube, Dniepr, Dniestr and Bug Rivers, and thus offers a more eutrophic and ecologically complex system.…”

Section: Methodsmentioning

confidence: 99%

Abrupt transition of the northwestern Black Sea shelf ecosystem from a eutrophic to an alternative pristine state

Oğuz¹,

Velikova²

2010

Mar. Ecol. Prog. Ser.

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Long-term (1960Long-term ( -2005 ecological data were used to identify a regime shift in the northwestern Black Sea shelf and to assess whether it has recovered from its former eutrophic state. Following the collapse of fish stocks and the population explosion of the ctenophore Mnemiopsis leidyi between 1988 and 1991, anthropogenic P-PO 4 loads from the River Danube dropped strongly in 1992-1993. This decline in P-PO 4 levels was caused by reductions in fertilizer use and emissions from land-based point sources during the economic recession of former Eastern Bloc countries, as well as by the low discharge rate of the River Danube. Commencing in 1993, the phosphate limitation apparently maintained a low-energy, inefficient food web dominated by the dinoflagellate Noctiluca scintillans and jellyfish, and relatively low levels of phytoplankton, bacterioplankton, mesozooplankton and fish. This 'post-eutrophication' regime was markedly different from the classical phytoplankton-mesozooplankton-fish chain of the similarly low nutrient 'pre-eutrophication' regime prior to 1970. Therefore it appears that the food web can attain 2 alternative regimes during periods of low productivity of the ecosystem. The post-eutrophication state cannot be considered as a major improvement or restoration of the northwestern coastal ecosystem.

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The influence of shelfbreak forcing on the alongshelf penetration of the Danube buoyant water, Black sea

Cited by 20 publications

References 25 publications

River‐induced particle distribution in the northwestern Black Sea (September 2002 and 2004)

River‐induced particle distribution in the northwestern Black Sea (September 2002 and 2004)

River Delta Morphodynamics: Examples from the Danube Delta

Abrupt transition of the northwestern Black Sea shelf ecosystem from a eutrophic to an alternative pristine state

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