Drivers of the autumn phytoplankton development in the open Black Sea

Mikaelyan, Alexander S.; Shapiro, Georgy; Часовников, В. К.; Wobus, Fred; Zanacchi, Marcus

doi:10.1016/j.jmarsys.2017.05.006

Cited by 30 publications

(25 citation statements)

References 36 publications

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“…The Black Sea is known to have both a spring phytoplankton bloom in March and a fall phytoplankton bloom. The fall bloom, usually found in late October and November, occurs when strong winds cause mixing and entrainment of nutrients into euphotic waters (Mikaelyan et al, 2017). The spring bloom alternates between diatoms and coccolithophores (Mikaelyan et al, 2015), and the fall bloom is composed mostly of diatoms (Stel'makh et al, 2009).…”

Section: Study Sitementioning

confidence: 99%

Detection of Transient Denitrification During a High Organic Matter Event in the Black Sea

Fuchsman

Paul

Staley

et al. 2019

Global Biogeochemical Cycles

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N2 production by denitrification can occur in anoxic water or potentially inside organic particles. Here we compare data from the Black Sea, a permanently anoxic basin, during two organic matter regimes: suspended particulate organic matter concentrations were high in the oxycline after the spring bloom in March 2005 compared to lower organic matter concentrations in June 2005, May and October 2007, July 2008, and May 2001. For all cruises, N2 gas had a maximum in the suboxic zone (O2 < 10 μmol/L). During the high organic matter event (March 2005), an additional shallower N2 gas and δ15N‐N2 maxima occurred above the suboxic zone in the oxycline where oxygen concentrations were 30–50 μmol/L. Examination of 16S rRNA indicated that anammox bacteria were not present in the oxycline. The δ15N of biologically produced N2 in the oxycline in March 2005 was significantly enriched (+7‰ to +38‰), not depleted, as would be expected from water column fractionation. A simple diffusion calculation indicated that ammonium produced from remineralization inside particles could be oxidized to nitrate and then completely consumed by denitrification inside the particle. In this calculation, half of denitrified N atoms originated from organic N [δ15N = 11‰] and half of N atoms originated from ambient nitrate [δ15N = 5‰–7‰], producing enriched δ15N‐N2 values. We suggest that denitrifiers were active in microzones inside particulates in hypoxic waters above the suboxic zone of the Black Sea. Denitrification in particles may also explain previous data from the oxycline above ocean oxygen deficient zones.

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Section: Study Sitementioning

confidence: 99%

Detection of Transient Denitrification During a High Organic Matter Event in the Black Sea

Fuchsman

Paul

Staley

et al. 2019

Global Biogeochemical Cycles

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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].…”

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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“…Анализ динамики Хл в Чёрном море по спутниковым данным был выполнен А. С. Микаэляном с соавторами на основе многолетних данных [16,17]. В этих работах для восстановления Хл по спутниковым наблюдениям использовали два алгоритма: 1) разработанный NASA и скорректированный для специальных условий открытых вод Чёрного моря [16]; 2) разработанный для Чёрного моря в Институте океанологии имени П. П. Ширшова (далее -ИО РАН) [14].…”

Section: результатыunclassified

Динамика концентрации хлорофилла a в Чёрном море по спутниковым измерениям

Финенко

Мансурова

Суслин

2019

mbj

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The use of satellite data to study the chlorophyll a dynamics, in contrast to contact methods, allows carrying out large scale research with high frequency of measurements. Such observations were carried out in the Black Sea offshore and inshore areas from 1998 to 2015. They made it possible to estimate the annual and interannual chlorophyll a dynamics in the surface layer and to reveal the periodicity, intensity, and duration of mass development of algae. In the western and eastern cyclonic gyres as well as in the shelf zone off the Crimean and Caucasus coasts, annual chlorophyll dynamics had the same pattern as that repeating year after year. From August-September to April-May of the next year the variation of chlorophyll in most cases corresponded to normal distribution and had a form of a bell-shaped curve with maximum observed in December-January. During autumn period, the chlorophyll concentration gradually increased with water cooling and seasonal pycnoclyne weakening. In winter the chlorophyll concentration decreased due to increase of mixed layer depth. Spring phytoplankton intensive development was observed every year when convective mixing weakened and stability of water column increased.

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Drivers of the autumn phytoplankton development in the open Black Sea

Cited by 30 publications

References 36 publications

Detection of Transient Denitrification During a High Organic Matter Event in the Black Sea

Detection of Transient Denitrification During a High Organic Matter Event in the Black Sea

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

Динамика концентрации хлорофилла a в Чёрном море по спутниковым измерениям

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