Phenology and drivers of the winter–spring phytoplankton bloom in the open Black Sea: The application of Sverdrup’s hypothesis and its refinements

Mikaelyan, Alexander S.; Часовников, В. К.; Kubryakov, A. A.; Stanichny, S. V.

doi:10.1016/j.pocean.2016.12.006

Cited by 24 publications

(23 citation statements)

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“…Recent studies show that the haline stratification, which determines the thickness of the main pycnocline in the Black Sea, is also undergoing strong changes [46]. In 1980-2010 decrease of salinity of the upper layer was noted, which should lead to a weakening of the vertical mixing (see works 1,2 , and also [47]). However, since 2015 a rather intensive increase in the upper layer salinity has been observed, partially compensating the thermal contribution to the density stratification of the Black Sea waters [15,45].…”

Section: Discussionmentioning

confidence: 99%

“…Large MLD can negatively affect the biological productivity of the basin, since the depth of the euphotic layer in winter is much smaller (~ 50 m) [4]. Therefore, in winter in the zones of the most intense downward movements on the continental slope and in the anticyclones a decrease in the chlorophyll a concentration can be expected [1,7].…”

Section: Winter Distribution Of Mld and Its Relation To Water Dynamicsmentioning

confidence: 99%

“…MLD variability strongly impact on the state of the marine ecosystem, as the vertical involvement of nutrients from the deep layers in ML is the main source of nutrients for phytoplankton in the central part of the Black Sea. The intensity of autumn-winter [1,2] and spring [3,4] blooming of diatoms directly depends on the vertical mixing processes. Summer blooming of coccolithophorids on an interannual scale correlates with winter cooling and the amount of phosphates involved in ML [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Summer blooming of coccolithophorids on an interannual scale correlates with winter cooling and the amount of phosphates involved in ML [5,6]. If the MLD significantly exceeds the photic layer thickness, in winter the phytoplankton blooming in the Black Sea can be suppressed [2] due to the general lack of illumination in ML [1,7].…”

Section: Introductionmentioning

confidence: 99%

“…Its three-dimensional structure (topography) is determined by the basin dynamics. On the basin scale, the dominant cyclonic circulation leads to pycnocline upraise in the cyclonic gyres in the central part of the sea and to its lowering over the continental slope in the Black Sea Rim Current zone (see the review in work 1 ). The intensity of the large-scale circulation at seasonal and interannual scales is determined by the wind vorticity [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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The Black Sea Mixed Layer Depth Variability and Its Relation to the Basin Dynamics and Atmospheric Forcing

Kubryakov¹,

Белокопытов²,

Zatsepin³

et al. 2019

PhO

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Spatio-temporal variability of the mixed layer depth (MLD) in different areas of the Black Sea in 1985-2017, its relationship with basin dynamics and atmospheric forcing are studied. Methods and Results. The study is based on the hydrological data archive for 1985-2017 including the measurements of the ship expeditions, the Argo buoys and the moored buoy "Aqalog". Seasonal and interannual variability of the mixed layer depth was determined using the density criterion (dr = = 0.07kg/m 3) between the surface layers and the base of the upper mixed layer. Conclusions. In January-March, the large-scale and mesoscale dynamics significantly affects the mixed layer depth variability. Minimum monthly average values of the mixed layer depth in winter are observed in the mesoscale cyclonic eddies and in the center of the sea (20-30 m), the moderate valueson the periphery of the basin (40-45 m) and the maximum onesin the mesoscale anticyclones (60-70 m). Several times the mixed layer depth values exceeding 150 m were detected in the downwelling areas of the basin. Analysis of the whole period (1985-2017) shows that the mixed layer density was never more than 1015 kg/m 3. This isopycnal limits the maximum possible depth of the upper mixed layer. The impact of wind velocity on the spatial and temporal variability of the mixed layer thickness is the largest in spring and autumn when the seasonal thermocline is weak. It is less important in summer when solar heating stabilizes the upper layer, and in winter when the mixed layer depth is large. Rise of the mixed layer depth in summer is observed in recent years that is associated with rise of the wind speed in a warm period of a year.

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Section: Discussionmentioning

confidence: 99%

Section: Winter Distribution Of Mld and Its Relation To Water Dynamicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The Black Sea Mixed Layer Depth Variability and Its Relation to the Basin Dynamics and Atmospheric Forcing

Kubryakov¹,

Белокопытов²,

Zatsepin³

et al. 2019

PhO

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Reconsideration of the phytoplankton seasonality in the open Black Sea

Yunev¹,

Carstensen

Stelmakh³

et al. 2020

Limnol Oceanogr Letters

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Phytoplankton production supports the entire food web of the open Black Sea, and it is believed that new production is sustained by inputs of nitrate from deeper waters during winter convective mixing. However, this current assertion is primarily based on analyses of chlorophyll a (Chl a) data, disregarding the large seasonal variations in cell-specific Chl a depending on the species, light intensity and nutrient concentrations. Our study shows that phytoplankton biomass in the open Black Sea primarily accumulates during late summer and autumn, when nitrate is depleted in the surface layer. The enhanced productivity could be driven by large diatoms harvesting nutrients from depths and nitrogen fixation by cyanobacteria, living in symbiotic relationship with diatoms.

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