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Ağırbaş, Ertuğrul; Feyzioglu, Ali Muzaffer; Kopuz, Ulgen

doi:10.4194/1303-2712-v14_3_14

Cited by 11 publications

(3 citation statements)

References 24 publications

(50 reference statements)

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“…Seasonal differences in normalized (on Chl-a) phytoplankton light absorbance capacity were related to strong changes in environmental conditions in UML, mainly due to the averaged PAR within UML (Figure 6). Observed seasonal dynamics of (UML) and euphotic zone in the deep open waters of the Black Sea are consistent with intraannual changes of these parameters (Z uml and Z eu ) in the Black Sea outlined earlier (Ivanov and Belokopytov, 2011;Agirbas et al, 2014).…”

Section: Discussionsupporting

confidence: 60%

Light Absorption by Phytoplankton in the Upper Mixed Layer of the Black Sea: Seasonality and Parametrization

et al. 2017

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Standard NASA ocean color algorithm OC4 was developed on the basis of ocean optical data and while appropriate for Case 1 oceanic waters could not be adequately applied for the Black Sea waters due to its different bio-optical properties. OC4 algorithm is shown to overestimate chlorophyll concentration (Chl-a) in summer and underestimate Chl-a during early spring phytoplankton blooms in the Black Sea. For correct conversion of satellite data to Chl-a, primary production and other indicators regional algorithms should be developed taking into account bio-optical properties of the Black Sea waters. Light absorption by phytoplankton pigments-a ph (λ) have been measured in open sea and shelf Black Sea waters in different seasons since 1998. It was shown that the first optical depth was located within the upper mixed layer (UML) for most of the year with the exception of the spring when seasonal stratification was developing. As a result spectral features of water leaving radiance were determined by optical properties of the UML. Significant seasonal differences in Chl-a specific light absorption coefficients of phytoplankton within UML have been revealed. These differences were caused by adaptive changes of composition and intracellular pigment concentration due to variable environment conditions-mainly light intensity. Empirical relationships between a ph (λ) and Chl-a were derived by least squares fitting to power functions for different seasons. Incorporation of these results will refine the regional ocean color models and provide improved and seasonally adjusted estimates of chlorophyll a concentration, downwelling radiance and primary production in the Black Sea based on satellite data.

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Section: Discussionsupporting

confidence: 60%

Light Absorption by Phytoplankton in the Upper Mixed Layer of the Black Sea: Seasonality and Parametrization

et al. 2017

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“…Chl-a was the lowest value in April (0.54 µg/L) and while Ch l-a was 1.41 µg L-1 in March, it decreased sharply in April and increased again to 1.65 µg L-1 in May (Figure 1). Ch l-a concentration was used as the basic criteria of the phytoplankton bio mass and researched intensively seasonal, annual and monthly variations (Vedernikov and Demidov, 1993;Oguz et al, 2002;Kopelevich et al, 2002;Moncheva, 2003;Agirbas et al, 2014). The Black Sea is characterized with two seasonal peaks of Chl-a in Autumn and Spring (Lalli and Parsons, 2004).…”

Section: Resultsmentioning

confidence: 99%

“…In the same sampling period, salinity of the sea surface was 18 ppt and it reached 19 ppt in 100 m depending on the depth. Agirbas et al (2014) reported that the thickness of the CIL was observed to be larger (65-130 m) in the coastal station of the Southeastern Black Sea (Trab zon coastline) and the salinity varied greatly within the range of 18 to 21‰ in the CIL during March 2010-December 2010. Measurements at Southeastern Coastal Site of the Black Sea (off Trab zon) took a decade (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011) and were docu mented by Alkan et al (2013).…”

Section: Statisticsmentioning

confidence: 99%

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Ozdemir¹,

Caf²,

Feyzioglu³

et al. 2017

Turk. J. Fish. Aquat. Sci.

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Noctiluca scintillans reached the highest abundance (5105 ind/m 3 ) in April; and April was an important period in the Black Sea ecosystem because of the seasonal thermocline. While the relationship between temperature and abundance was important (P<0.05, r 2 =-0.8), the relationship was not important between salinity and abundance (P<0.05, r 2 =-0.06); and Chlorophyll-a (Chl-a) and abundance (P<0.05, r 2 =-0.2). It was determined that total lipid was 0.5% in wet weight (WW). It was shown that the main Saturated Fatty Acids (SFA) were 16:0 (24%) and 18:0 (6%), main M onounsaturated Fatty Acids (MUFA) were 18:1ω-9c (22%) and 16:1ω-7 (4%), main Polyunsaturated Fatty Acids (PUFA) were 18:2ω-6c (19%) and 20:4ω-6c (8%). Phytosterols were the most important sterols in N. scintillans; and stigmasterol was 60 µg/gr and β-sterol was 8µg/gr as the most important ones in phytosterols. α-tocopherol was the highest amount (10.8 µg/g) in lipophilic vitamins. It was found that M alondialdehyde (M DA) was 65 µg/g, total protein was 10 mg/g, Glutathione (GSH) was 10565 µg/g and GSSG) was 49 µg/g. Consequently, PUFA and α-tocopherol were the most important biochemical parameters and α-tocopherol may reduce toxicity in blooms of N. scintillans because of inhibitory effect of α-tocopherol on lipid oxidation. Additionally, we can say that N. scintillans is a resistant dinoflagellate against oxidative stress.

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Mercury in the Black Sea: New Insights From Measurements and Numerical Modeling

Rosati

Heimbürger

Canu

et al. 2018

Global Biogeochemical Cycles

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Redox conditions and organic matter control marine methylmercury (MeHg) production. The Black Sea is the world's largest and deepest anoxic basin and is thus ideal to study Hg species along the extended redox gradient. Here we present new dissolved Hg and MeHg data from the 2013 GEOTRACES MEDBlack cruise (GN04_leg2) that we integrated into a numerical 1‐D model, to track the fate and dynamics of Hg and MeHg. Contrary to a previous study, our new data show highest MeHg concentrations in the permanently anoxic waters. Observed MeHg/Hg percentage (range 9–57%) in the anoxic waters is comparable to other subsurface maxima in oxic open‐ocean waters. With the modeling we tested for various Hg methylation and demethylation scenarios along the redox gradient. The results show that Hg methylation must occur in the anoxic waters. The model was then used to simulate the time evolution (1850–2050) of Hg species in the Black Sea. Our findings quantify (1) inputs and outputs of Hg T (~31 and ~28 kmol yr −1 ) and MeHg T (~5 and ~4 kmol yr −1 ) to the basin, (2) the extent of net demethylation occurring in oxic (~1 kmol yr −1 ) and suboxic water (~6 kmol yr −1 ), (3) and the net Hg methylation in the anoxic waters of the Black Sea (~11 kmol yr −1 ). The model was also used to estimate the amount of anthropogenic Hg (85–93%) in the Black Sea.

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Cited by 11 publications

References 24 publications

Light Absorption by Phytoplankton in the Upper Mixed Layer of the Black Sea: Seasonality and Parametrization

Light Absorption by Phytoplankton in the Upper Mixed Layer of the Black Sea: Seasonality and Parametrization

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Mercury in the Black Sea: New Insights From Measurements and Numerical Modeling

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