Coccolithophorids in the Black Sea: Their interannual and long-term changes

Mikaelyan, Alexander S.; Силкин, В. А.; Паутова, Л. А.

doi:10.1134/s0001437011010127

Cited by 56 publications

(35 citation statements)

References 21 publications

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“…In a number of works [3,4] it was shown that interannual variability of chlorophyll a concentration is closely related to the minimum winter temperature of the sea surface (SST) which is an indicator of winter severity and vertical mixing intensity. The bloom of phytoplankton, for example coccolithophores, in the warm period of the year significantly depends on winter cooling and on the amount of nutrients supplied during the winter, the phosphates in particular [9,10]. Among other important mechanisms of nutrient supply, horizontal cross-shelf transport can be noted.…”

mentioning

confidence: 99%

Impact of Winter Cooling on Water Vertical Entrainment and Intensity of Phytoplankton Bloom in the Black Sea

Kubryakova¹,

Kubryakov²,

Stanichny³

2018

PhO

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Vertical entrainment of nutrients and phytoplankton from the subsurface layers in autumn -winter is a cause of the surface phytoplankton bloom in the Black Sea in winter. Relationship of the winter heat flux and the sea surface temperature (SST) with the integral and surface phytoplankton biomass is assessed based on a series of simulations performed due to a 1D-biogeochemical model. The results show that during severe winters, intensity of phytoplankton bloom is 50% higher than that in warm winters. Winter entrainment of nutrients influences the phytoplankton biomass in the subsurface layer in summer, namely, after cold winters its maximum value exceeds the analogous one after warm winters by ≈30%. In-situ data is used to estimate the relation between the upper mixed layer depth and density, and the integral concentration of nitrates and phosphates in various regions of the basin. It is revealed that growth of the upper mixed layer density from 1014.0 to 1014.2 kg/m 3 results in increase of the integral concentration of nutrients in the upper layer by 2-2.5 times in the center and on the periphery of the basin; and when the density value achieves 1014.5 kg/m 3 the integral concentration becomes higher by 4-5 times. Thus the upper mixed layer density serves a good indicator of intensity of the nutrients inflow to the sea upper layers. Impact of winter cooling upon the upper mixed layer density is investigated using the model and in-situ data. It is shown that density equal to 1014.2 kg/m 3 is achieved in the basin center at SST 7.5-8° C, and on the sea periphery -at 6.5° C. The maximum density value 1014.8 kg/m 3 is recorded in the center of the sea (depth exceeds 2000 m) at SST < 5.5° C. During the same atmospheric conditions, the vertical nutrient transport is different in various regions of the Black Sea, which can affect the spatial features of bloom intensity in the basin. Acknowledgements:The data were obtained and processed within the framework of the State Order No. 0827-2014-0011 "The research of regularities of marine environment condition changes on the basis of operational observations and the data of marine area condition nowcast, forecast and reanalysis system" ("Operative oceanography" code); model calculations were carried out with the financial support of RFBR

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mentioning

confidence: 99%

Impact of Winter Cooling on Water Vertical Entrainment and Intensity of Phytoplankton Bloom in the Black Sea

Kubryakova¹,

Kubryakov²,

Stanichny³

2018

PhO

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“…The estimated concentration of the mineral suspension during coccolithophore bloom in 2012 was ~1 , corresponding under the order of values to the blooms fixed in 1992 and 2006. These data indicate that the observed bloom has been one of the most intense in recent years [20].…”

Section: Datamentioning

confidence: 67%

“…On the average the concentration value was 1.2 · 10 11 m -3 , which corresponds to the concentration of coccolithophore cell about 6 10 cells·l -1 . The obtained concentrations of the mineral suspension, as well as the 3 -4 times higher than usual reflectance coefficients, indicate that the bloom observed has been one of the most intense in recent years [20]. Conclusion.…”

Section: Datamentioning

confidence: 90%

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Determination of the Concentration of Seawater Components based on Upwelling Radiation Spectrum

Lee¹,

Shybanov²,

Korchemkina³

et al. 2016

PhO

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Results of seawater reflectance measurements carried out in the Black Sea coastal waters in the summer-autumn season, 2002-2014 on the oceanographic platform of the Experimental Department of MHI are discussed. The data were obtained using the spectrophotometer developed in the Marine Optics Department of MHI. Special measuring technique allows one to take into account the light reflected by the sea surface that eliminates necessity in sub-surface probing and provides higher accuracy as compared to the results of the model simulations. The measurements show that in the summer-autumn period the sea reflectance spectra are of almost constant shape with a smooth peak in the range 480-500 nm. The peak values usually lie within between 1% (October) and 2% (July), except for the spectra measured during the coccolythophore bloom in 2012 when the peak values reached 6.6% (4.5% on average). The semi-analytical algorithm of reflectance data processing permits to obtain inherent optical properties of seawater including the phytoplankton pigments' concentration, absorption by nonliving organic matter and scattering by marine particles, and also to detect the auxiliary photosynthetic pigments from the reconstructed phytoplankton absorption spectrum. Special optimization technique permitting to simplify and to stabilize calculations is introduced. The chlorophyll-a concentrations obtained using the algorithm are in good agreement with direct biological data. Simultaneous measurements of reflectance and chlorophyll-a concentration performed during the sub-satellite experiment in [2002][2003][2004] have shown that discrepancy between the modeled and the measured concentrations was about 10%. The considered method permits to carry out operational sub-satellite monitoring of marine environment and, in particular, to validate the algorithms for processing remote sensing data.

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“…There are also longterm trends that reduce or increase the contribution of one or other of the species in the community structure. In particular, in the Black Sea the coccolithophore growth has been heightened over the last two decades (Pautova et al 2007;Mikaelyan et al 2011). Obviously, to become successfully fixed in the ecosystem, the invasive species should be installed in the appropriate seasonal complex or they can at least coexist with the dominant species in a given season.…”

Section: Introductionmentioning

confidence: 97%

Mechanisms of regulation of invasive processes in phytoplankton on the example of the north-eastern part of the Black Sea

et al. 2016

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In the north-eastern part of the Black Sea, the seasonal complexes of dominant species of phytoplankton were fixed: small-celled diatom (spring), coccolithophores (late spring, early summer) and large diatoms (summer and autumn). In May-June 2005 and 2006, two invasive species of marine diatoms Chaetoceros throndsenii (maximal abundance 1.92 9 10 5 cells/l) and Chaetoceros minimus (1.6 9 10 5 cells/l) were recorded. These species have been incorporated in the complex of the late spring and early summer and grew simultaneously with the coccolithophore Emiliania huxleyi. The coccolithophore was dominant species, whose abundance had reached the level of a bloom. C. throndsenii was observed over the entire area from the coast to the centre of the sea; C. minimus were recorded at coastal stations and only at two stations of the open sea. Stratification of the water mass and the low (below the Redfield) ratio of nitrogen to phosphorus were observed at this time. Then, C. throndsenii was not marked even once, and C. minimus has been registered once on a shelf in June 2011. Experimental studies (2005) have shown that intensive growth C. throndsenii requires the simultaneous addition of nitrogen and phosphorus in a ratio close to the Redfield ratio. C. minimus shows the intensive growth only at high concentrations of phosphorus and at low nitrogento-phosphorus ratio (the experiment was carried out in June 2011). Mathematical modelling shows that C. throndsenii and Emiliania huxleyi form a stable couple whose growth is limited by different factors: the diatoms by nitrogen and the coccolithophores by phosphorus. C. minimus might not be able to form a stable couple with coccolithophores because they have the same limiting factor, i.e. phosphorus. However, this species could become the dominant one, if low (0.5-1) nitrogen-tophosphorus ratio conditions were stable for more than 2 months. However, this scenario is improbable in natural circumstances since the existence of this complex seasonal rarely exceeds 1.5 months.

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Coccolithophorids in the Black Sea: Their interannual and long-term changes

Cited by 56 publications

References 21 publications

Impact of Winter Cooling on Water Vertical Entrainment and Intensity of Phytoplankton Bloom in the Black Sea

Impact of Winter Cooling on Water Vertical Entrainment and Intensity of Phytoplankton Bloom in the Black Sea

Determination of the Concentration of Seawater Components based on Upwelling Radiation Spectrum

Mechanisms of regulation of invasive processes in phytoplankton on the example of the north-eastern part of the Black Sea

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