Dynamics of the deep chlorophyll maximum in the Black Sea as depicted by BGC-Argo floats

Ricour, Florian; Capet, Arthur; D'Ortenzio, Fabrizio; Delille, Bruno; Grégoire, Marilaure

doi:10.5194/bg-18-755-2021

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Dynamics of the deep chlorophyll maximum in the Black Sea as depicted by BGC-Argo floats

Ricour, Florian; Capet, Arthur; D'Ortenzio, Fabrizio et al.

2021 • In Biogeosciences, 18, p. 755–774

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https://hdl.handle.net/2268/256777

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10.5194/bg-18-755-2021

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Keywords :

Deep Chlorophyll Maximum; Black Sea; Argo floats

Abstract :

[en] This paper addresses the phenology of the deep chlorophyll maximum (DCM) in the Black Sea (BS). We show that the DCM forms in March at a density level set by the winter mixed layer. It maintains this location until June, suggesting an influence of the DCM on light and nutrient profiles rather than mere adaptation to external factors. In summer, the DCM concentrates ~55 % of the chlorophyll in a 10 m layer at ~35 m depth and should be considered a major feature of the BS phytoplankton dynamics.

Research Center/Unit :

FOCUS - Freshwater and OCeanic science Unit of reSearch - ULiège

Disciplines :

Earth sciences & physical geography

Author, co-author :

Ricour, Florian ^✱; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > MAST (Modeling for Aquatic Systems)

Capet, Arthur ^✱; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > MAST (Modeling for Aquatic Systems)

D'Ortenzio, Fabrizio; Laboratoire d'Océanographie de Villefranche,, Sorbonne Universités, Villefranche-sur-Mer, France

Delille, Bruno ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)

Grégoire, Marilaure ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > MAST (Modeling for Aquatic Systems)

^✱ These authors have contributed equally to this work.

Language :

English

Title :

Dynamics of the deep chlorophyll maximum in the Black Sea as depicted by BGC-Argo floats

Publication date :

February 2021

Journal title :

Biogeosciences

ISSN :

1726-4170

eISSN :

1726-4189

Publisher :

European Geosciences Union (EGU), Germany

Volume :

Pages :

755–774

Peer reviewed :

Peer Reviewed verified by ORBi

Additional URL :

https://bg.copernicus.org/articles/18/755/2021/bg-18-755-2021.html
http://doi.org/10.5281/zenodo.4381774

Funders :

F.R.S.-FNRS - Fonds de la Recherche Scientifique

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since 12 February 2021

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Bibliography

Anderson, G.: Subsurface chlorophyll maximum in the northeast Pacific Ocean, Limnol. Oceanogr., 14, 386-391, 1969.
Ardyna, M., Babin, M., Gosselin, M., Devred, E., Bélanger, S., Matsuoka, A., and Tremblay, J.-É.: Parameterization of vertical chlorophyll a in the Arctic Ocean: Impact of the subsurface chlorophyll maximum on regional, seasonal, and annual primary production estimates, Biogeosciences, 10, 4383-4404, https://doi.org/10.5194/bg-10-4383-2013, 2013.
Argo: Argo float data and metadata from Global Data Assembly Centre (Argo GDAC), SEANOE, https://doi.org/10.17882/42182, 2020.
Argo Data Management Team (Carval Thierry, Keeley Robert, Takatsuki Yasushi, Yoshida Takashi, Loch Stephen, Schmid Claudia, Goldsmith Roger, Wong Annie, McCreadie Rebecca, Thresher Ann, Tran Anh): Argo user's manual V3.4, Ifremer, https://doi.org/10.13155/29825, 2021.
Beckmann, A. and Hense, I.: Beneath the surface: Characteristics of oceanic ecosystems under weak mixing conditions-a theoretical investigation, Prog. Oceanogr., 75, 771-796, 2007.
Capet, A., Troupin, C., Carstensen, J., Grégoire, M., and Beckers, J.-M.: Untangling spatial and temporal trends in the variability of the Black Sea Cold Intermediate Layer and mixed Layer Depth using the DIVA detrending procedure, Ocean Dynam., 64, 315-324, 2014.
Carranza, M. M., Gille, S. T., Franks, P. J., Johnson, K. S., Pinkel, R., and Girton, J. B.: When Mixed Layers Are Not Mixed. Storm-Driven Mixing and Bio-optical Vertical Gradients in Mixed Layers of the Southern Ocean, J. Geophys. Res.-Oceans, 123, 7264-7289, 2018.
Chiswell, S. M., Calil, P. H. R., and Boyd, P.W.: Spring blooms and annual cycles of phytoplankton: A unified perspective, J. Plankton Res., 37, 500-508, https://doi.org/10.1093/plankt/fbv021, 2015.
Churilova, T., Suslin, V., Krivenko, O., Efimova, T., Moiseeva, N., Mukhanov, V., and Smirnova, L.: Light absorption by phytoplankton in the upper mixed layer of the Black Sea: Seasonality and parametrization, Front. Mar. Sci., 4, 90, https://doi.org/10.3389/fmars.2017.00090, 2017.
Claustre, H., Antoine, D., Boehme, L., Boss, E., D'Ortenzio, F., D'Andon, O. F., Guinet, C., Gruber, N., Handegard, N. O., Hood, M., Johnson, K., Kortzinger, A., Lampitt, R., LeTraon, P.-Y., Le Quere, C., Lewis, M., Perry, M.-J., Platt, T., Roemmich, D., Sathyendranath, S., Send, U., Testor, P., and Yoder, J.: Guidelines towards an integrated ocean observation system for ecosystems and biogeochemical cycles, in: Proceedings of OceanObs'09: Sustained Ocean Observations and Information for Society, Vol. 1, edited by: Hall, J., Harrison, D. E., and Stammer, D., European Space Agency, Noordwijk, the Netherlands, 2009.
Coble, P., Gagosian, R., Codispoti, L., Friederich, G., and Christensen, J.: Vertical distribution of dissolved and particulate fluorescence in the Black Sea, Deep-Sea Res. Pt. A, 38, S985-S1001, 1991.
Cullen, J.: The deep chlorophyll maximum: Comparing vertical profiles of chlorophyll a, Can. J. Fish. Aquat. Sci., 39, 791-803, 1982.
Cullen, J.: Subsurface chlorophyll maximum layers: Enduring enigma or mystery solved?, Annu. Rev. Mar. Sci., 7, 207-239, 2015.
de Boyer Montégut, C., Madec, G., Fischer, A., Lazar, A., and Iudicone, D.: Mixed layer depth over the global ocean: An examination of profile data and a profile-based climatology, J. Geophys. Res.-Oceans, 109, 1-20, 2004.
Dubinsky, Z. and Stambler, N.: Photoacclimation processes in phytoplankton: Mechanisms, consequences, and applications, Aquat. Microb. Ecol., 56, 163-176, 2009.
Ducklow, H. W., Hansell, D. A., and Morgan, J. A.: Dissolved organic carbon and nitrogen in theWestern Black Sea, Mar. Chem., 105, 140-150, 2007.
Ediger, D. and Yilmaz, A.: Characteristics of deep chlorophyll maximum in the Northeastern Mediterranean with respect to environmental conditions, J. Marine Syst., 9, 291-303, 1996.
Estrada, M., Marrase, C., Latasa, M., Berdalet, E., Delgado, M., and Riera, T.: Variability of deep chlorophyll maximum characteristics in the northwestern Mediterranean, Mar. Ecol. Prog. Ser., 92, 289-300, 1993.
Falina, A., Sarafanov, A., Özsoy, E., and Utku Turunçoǧlu, U.: Observed basin-wide propagation of Mediterranean water in the Black Sea, J. Geophys. Res.-Oceans, 122, 3141-3151, https://doi.org/10.1002/2017JC012729, 2017.
Fennel, K. and Boss, E.: Subsurface maxima of phytoplankton and chlorophyll: Steady-state solutions from a simple model, Limnol. Oceanogr., 48, 1521-1534, 2003.
Filonov, A. E.: Thermic structure and intense internal waves on the narrow continental shelf of the Black Sea, J. Marine Syst., 24, 27-40, https://doi.org/10.1016/S0924-7963(99)00077-9, 2000.
Finenko, Z., Churilova, T., and Lee, R.: Dynamics of the vertical distributions of chlorophyll and phytoplankton biomass in the Black Sea, Oceanology, 45, S112-S126, 2005.
Finenko, Z., Suslin, V., and Kovaleva, I.: Seasonal and long-term dynamics of the chlorophyll concentration in the Black Sea according to satellite observations, Oceanology, 54, 596-605, 2014.
Furuya, K.: Subsurface chlorophyll maximum in the tropical and subtropical western Pacific Ocean: Vertical profiles of phytoplankton biomass and its relationship with chlorophylla and particulate organic carbon, Mar. Biol., 107, 529-539, 1990.
Grégoire, M. and Beckers, J. M.: Modeling the nitrogen fluxes in the Black Sea using a 3D coupledhydrodynamicalbiogeochemical model: Transport versus biogeochemicalprocesses, exchanges across the shelf break and comparison of the shelf anddeep sea ecodynamics, Biogeosciences, 1, 33-61, https://doi.org/10.5194/bg-1-33-2004, 2004.
Huisman, J., van Oostveen, P., and Weissing, F. J.: Species Dynamics in Phytoplankton Blooms: Incomplete Mixing and Competition for Light, Am. Nat., 154, 46-68, https://doi.org/10.1086/303220, 1999.
Huisman, J., Pham Thi, N., Karl, D., and Sommeijer, B.: Reduced mixing generates oscillations and chaos in the oceanic deep chlorophyll maximum, Nature, 439, 322-325, 2006.
IOC, SCOR and IAPSO: The international thermodynamic equation of seawater - 2010: Calculation and use of thermodynamic properties, Intergovernmental Oceanographic Commission, Manuals and Guides No. 56, UNESCO, 196 pp., 2010.
IOCCG: Phytoplankton Functional Types from Space, edited by: Sathyendranath, S., Reports of the International Ocean-Colour Coordinating Group, No. 15, IOCCG, Dartmouth, Canada, 2014.
Ivanov, L. I., Beşiktepe, Ş., and Özsoy, E.: The Black Sea Cold Intermediate Layer, in: Sensitivity to Change: Black Sea, Baltic Sea and North Sea, edited by: Özsoy, E. and Mikaelyan, A., Springer Netherlands, Dordrecht, https://doi.org/10.1007/978-94-011-5758-2_20, 253-264, 1997.
Kara, A. B., Wallcraft, A. J., and Hurlburt, H. E.: Sea surface temperature sensitivity to water turbidity from simulations of the turbid Black Sea using HYCOM, J. Phys. Oceanogr., 35, 33-54, 2005.
Kara, A. B., Helber, R. W., Boyer, T. P., and Elsner, J. B.: Mixed layer depth in the Aegean, Marmara, Black and Azov Seas: Part I: General features, J. Marine Syst., 78, S169-S180, 2009.
Karabashev, G.: Diurnal rhythm and vertical distribution of chlorophyll fluorescence as evidence of bacterial photosynthetic activity in the Black Sea, Ophelia, 40, 229-238, 1995.
Klausmeier, C. A. and Litchman, E.: Algal games: The vertical distribution of phytoplankton in poorly mixed water columns, Limnol. Oceanogr., 46, 1998-2007, https://doi.org/10.4319/lo.2001.46.8.1998, 2001.
Konovalov, S. and Murray, J.: Variations in the chemistry of the Black Sea on a time scale of decades (1960-1995), J. Marine Syst., 31, 217-243, 2001.
Konovalov, S. K., Murray, J. W., Luther, G. W., and Tebo, B. M.: Processes controlling the redox budget for the oxic/anoxic water column of the Black Sea, Deep-Sea Res. Pt. 2, 53, 1817-1841, https://doi.org/10.1016/j.dsr2.2006.03.013, 2006.
Kopelevich, O. V., Sheberstov, S. V., Yunev, O., Basturk, O., Finenko, Z. Z., Nikonov, S., and Vedernikov, V. I.: Surface chlorophyll in the Black Sea over 1978-1986 derived from satellite and in situ data, J. Marine Syst., 36, 145-160, https://doi.org/10.1016/S0924-7963(02)00184-7, 2002.
Kubryakova, E. A. and Kubryakov, A. A.: Warmer winter causes deepening and intensification of summer subsurface bloom in the Black Sea: The role of convection and self-shading mechanism, Biogeosciences Discuss. [preprint], https://doi.org/10.5194/bg-2020-210, 2020.
Lavigne, H., D'Ortenzio, F., Ribera D'Alcalà, M., Claustre, H., Sauzède, R., and Gacic, M.: On the vertical distribution of the chlorophyll a concentration in the Mediterranean Sea: A basinscale and seasonal approach, Biogeosciences, 12, 5021-5039, https://doi.org/10.5194/bg-12-5021-2015, 2015.
Letelier, R. M., Karl, D. M., Abbott, M. R., and Bidigare, R. R.: Light driven seasonal patterns of chlorophyll and nitrate in the lower euphotic zone of the North Pacific Subtropical Gyre, Limnol. Oceanogr., 49, 508-519, 2004.
Macedo, M., Duarte, P., Ferreira, J., Alves, M., and Costa, V.: Analysis of the deep chlorophyll maximum across the Azores Front, Hydrobiologia, 441, 155-172, 2000.
Margolin, A. R., Gerringa, L. J. A., Hansell, D. A., and Rijkenberg, M. J. A.: Net removal of dissolved organic carbon in the anoxic waters of the Black Sea, Mar. Chem., 183, 13-24, https://doi.org/10.1016/j.marchem.2016.05.003, 2016.
Margolin, A. R., Gonnelli, M., Hansell, D. A., and Santinelli, C.: Black Sea dissolved organic matter dynamics: Insights from optical analyses, Limnol. Oceanogr., 2018.
Marra, J.: Analysis of diel variability in chlorophyll fluorescence, J. Mar. Res., 55, 767-784, 1997.
Mignot, A., Claustre, H., D'Ortenzio, F., Xing, X., Poteau, A., and Ras, J.: From the shape of the vertical profile of in vivo fluorescence to Chlorophyll-a concentration, Biogeosciences, 8, 2391-2406, https://doi.org/10.5194/bg-8-2391-2011, 2011.
Mignot, A., Claustre, H., Uitz, J., Poteau, A., D'Ortenzio, F., and Xing, X.: Understanding the seasonal dynamics of phytoplankton biomass and the deep chlorophyll maximum in oligotrophic environments: A Bio-Argo float investigation, Global Biogeochem. Cy., 28, 856-876, 2014.
Mikaelyan, A. S., Chasovnikov, V. K., Kubryakov, A. A., and Stanichny, S. V.: Phenology and drivers of the winter-spring phytoplankton bloom in the open Black Sea: The application of Sverdrup's hypothesis and its refinements, Prog. Oceanogr., 151, 163-176, 2017a.
Mikaelyan, A. S., Shapiro, G. I., Chasovnikov, V. K., Wobus, F., and Zanacchi, M.: Drivers of the autumn phytoplankton development in the open Black Sea, J. Marine Syst., 174, 1-11, https://doi.org/10.1016/j.jmarsys.2017.05.006, 2017b.
Mikaelyan, A. S., Kubryakov, A. A., Silkin, V. A., Pautova, L. A., and Chasovnikov, V. K.: Regional climate and patterns of phytoplankton annual succession in the open waters of the Black Sea, Deep-Sea Res. Pt. I, 142, 44-57, https://doi.org/10.1016/j.dsr.2018.08.001, 2018.
Mikaelyan, A. S., Mosharov, S. A., Kubryakov, A. A., Pautova, L. A., Fedorov, A., and Chasovnikov, V. K.: The impact of physical processes on taxonomic composition, distribution and growth of phytoplankton in the open Black Sea, J. Marine Syst., 208, 103368, https://doi.org/10.1016/j.jmarsys.2020.103368, 2020.
Miladinova, S., Stips, A., Garcia-Gorriz, E., and Macias Moy, D.: Formation and changes of the Black Sea cold intermediate layer, Prog. Oceanogr., 167, 11-23, https://doi.org/10.1016/j.pocean.2018.07.002, 2018.
Moré, J. J.: The Levenberg-Marquardt algorithm: Implementation and theory, in: Numerical analysis, Springer, Berlin, Heidelberg, 105-116, 1978.
Murray, J. W., Top, Z., and Özsoy, E.: Hydrographic properties and ventilation of the Black Sea, Deep-Sea Res. Pt. A, 38, S663-S689, 1991.
Navarro, G. and Ruiz, J.: Hysteresis conditions the vertical position of deep chlorophyll maximum in the temperate ocean, Global Biogeochem. Cy., 27, 1013-1022, 2013.
Nelson, N. B. and Siegel, D. A.: The global distribution and dynamics of chromophoric dissolved organic matter, Annu. Rev. Mar. Sci., 5, 447-476, https://doi.org/10.1146/annurev-marine-120710-100751, 2013.
Organelli, E., Bricaud, A., Antoine, D., and Matsuoka, A.: Seasonal dynamics of light absorption by chromophoric dissolved organic matter (CDOM) in the NW Mediterranean Sea (BOUSSOLE site), Deep-Sea Res. Pt. I, 91, 72-85, https://doi.org/10.1016/j.dsr.2014.05.003, 2014.
Organelli, E., Claustre, H., Bricaud, A., Schmechtig, C., Poteau, A., Xing, X., Prieur, L., D'Ortenzio, F., Dall'Olmo, G., and Vellucci, V.: A novel near-real-time quality-control procedure for radiometric profiles measured by bio-argo floats: Protocols and performances, J. Atmos. Ocean. Tech., 33, 937-951, 2016.
Ostrovskii, A. G. and Zatsepin, A. G.: Intense ventilation of the Black Sea pycnocline due to vertical turbulent exchange in the Rim Current area, Deep-Sea Res. Pt. I, 116, 1-13, https://doi.org/10.1016/j.dsr.2016.07.011, 2016.
Özsoy, E., Di Iorio, D., Gregg, M. C., and Backhaus, J. O.: Mixing in the Bosphorus Strait and the Black Sea continental shelf: Observations and a model of the dense water outflow, J. Marine Syst., 31, 99-135, https://doi.org/10.1016/S0924-7963(01)00049-5, 2001.
Para, J., Coble, P. G., Charrière, B., Tedetti, M., Fontana, C., and Sempéré, R.: Fluorescence and absorption properties of chromophoric dissolved organic matter (CDOM) in coastal surface waters of the northwestern Mediterranean Sea, influence of the Rhône River, Biogeosciences, 7, 4083-4103, https://doi.org/10.5194/bg-7-4083-2010, 2010.
Parslow, J. S., Boyd, P.W., Rintoul, S. R., and Griffiths, F. B.: A persistent subsurface chlorophyll maximum in the Interpolar Frontal Zone south of Australia: Seasonal progression and implications for phytoplankton-light-nutrient interactions, J. Geophys. Res.-Oceans, 106, 31543-31557, 2001.
Podymov, O., Zatsepin, A., Kubryakov, A., and Ostrovskii, A.: Seasonal and interannual variability of vertical turbulent exchange coefficient in the Black Sea pycnocline in 2013-2016 and its relation to variability of mean kinetic energy of surface currents, Ocean Dynam., 70, 199-211, https://doi.org/10.1007/s10236-019-01331-w, 2020.
Proctor, C. and Roesler, C.: New insights on obtaining phytoplankton concentration and composition from in situ multispectral Chlorophyll fluorescence, Limnol. Oceanogr.-Meth., 8, 695-708, 2010.
Ras, J., Claustre, H., and Uitz, J.: Spatial variability of phytoplankton pigment distributions in the Subtropical South Pacific Ocean: Comparison between in situ and predicted data, Biogeosciences, 5, 353-369, https://doi.org/10.5194/bg-5-353-2008, 2008.
Richardson, T. L. and Cullen, J. J.: Changes in buoyancy and chemical composition during growth of a coastal marine diatom: Ecological and biogeochemical consequences, Mar. Ecol.-Prog. Ser., 128, 77-90, 1995.
Ricour, F. and Capet, A.: Fricour/DCM-Black-Sea-Paper: Final release of data and scripts used in the frame of the paper entitled "Dynamics of the Deep Chlorophyll Maximum in the Black Sea as depicted by BGC-Argo floats", https://doi.org/10.5281/zenodo.4381774, 2020.
Roesler, C., Uitz, J., Claustre, H., Boss, E., Xing, X., Organelli, E., Briggs, N., Bricaud, A., Schmechtig, C., Poteau, A., D'Ortenzio, F., Ras, J., Drapeau, S., Haëntjens, N., and Barbieux, M.: Recommendations for obtaining unbiased chlorophyll estimates from in situ chlorophyll fluorometers: A global analysis of WET Labs ECO sensors, Limnol. Oceanogr.-Meth., 15, 572-585, 2017.
Röttgers, R. and Koch, B. P.: Spectroscopic detection of a ubiquitous dissolved pigment degradation product in subsurface waters of the global ocean, Biogeosciences, 9, 2585-2596, https://doi.org/10.5194/bg-9-2585-2012, 2012.
Schmechtig, C., Claustre, H., Poteau, A., and D'Ortenzio, F.: Bio-Argo quality control manual for the Chlorophyll-A concentration, Ifremer, https://doi.org/10.13155/35385, 2018.
Stanev, E., He, Y., Grayek, S., and Boetius, A.: Oxygen dynamics in the Black Sea as seen by Argo profiling floats, Geophys. Res. Lett., 40, 3085-3090, 2013.
Stanev, E. V., Bowman, M. J., Peneva, E. L., and Staneva, J. V.: Control of Black Sea intermediate water mass formation by dynamics and topography: Comparison of numerical simulations, surveys and satellite data, J. Marine Res., 61, 59-99, https://doi.org/10.1357/002224003321586417, 2003.
Sverdrup, H. U.: On conditions for the vernal blooming of phytoplankton, J. Cons. Int. Explor. Mer., 18, 287-295, 1953.
Terzić, E., Lazzari, P., Organelli, E., Solidoro, C., Salon, S., D'Ortenzio, F., and Conan, P.: Merging bio-optical data from Biogeochemical-Argo floats and models in marine biogeochemistry, Biogeosciences, 16, 2527-2542, https://doi.org/10.5194/bg-16-2527-2019, 2019.
Tugrul, S., Basturk, O., Saydam, C., and Yilmaz, A.: Changes in the hydrochemistry of the Black Sea inferred from water density profiles, Nature, 359, 137-139, 1992.
Varela, R., Cruzado, A., Tintore, J., and Garcia Ladona, E.: Modelling the deep-chlorophyll maximum: A coupled physical-biological approach, J. Marine Res., 50, 441-463, 1992.
Wong, A., Keeley, R., Carval, T., and the Bio Argo Team: Argo Quality Control Manual for CTD and Trajectory Data, Ifremer, https://doi.org/10.13155/33951, 2018.
Xing, X., Morel, A., Claustre, H., Antoine, D., D'Ortenzio, F., Poteau, A., and Mignot, A.: Combined processing and mutual interpretation of radiometry and fluorimetry from autonomous profiling Bio-Argo floats: Chlorophyll a retrieval, J. Geophys. Res.-Oceans, 116, C06020, https://doi.org/10.1029/2010JC006899, 2011.
Xing, X., Claustre, H., Blain, S., D'Ortenzio, F., Antoine, D., Ras, J., and Guinet, C.: Quenching correction for in vivo chlorophyll fluorescence acquired by autonomous platforms: A case study with instrumented elephant seals in the Kerguelen region (Southern Ocean), Limnol. Oceanogr.-Meth., 10, 483-495, 2012.
Xing, X., Claustre, H., Boss, E., Roesler, C., Organelli, E., Poteau, A., Barbieux, M., and D'Ortenzio, F.: Correction of profiles of insitu chlorophyll fluorometry for the contribution of fluorescence originating from non-algal matter, Limnol. Oceanogr.-Meth., 15, 80-93, 2017.
Yilmaz, A., Ediger, D., Basturk, O., and Tugrul, S.: Phytoplankton fluorescence and deep chlorophyll maxima in the northeastern Mediterranean, Oceanol. Acta, 17, 69-77, 1994.
Yunev, O. A., Moncheva, S., and Carstensen, J.: Long-term variability of vertical chlorophyll a and nitrate profiles in the open Black Sea: Eutrophication and climate change, Mar. Ecol.-Prog. Ser., 294, 95-107, 2005