4 - Year Algal Blooms Monitoring of the Western Black Sea Coast Using Sentinel - 3 Data
DOI:
https://doi.org/10.29227/IM-2026-01-01-0031Keywords:
chlorophyll-a, algal blooms, phytoplankton, eutrophication, Sentinel-3 data, Western Black Sea coastAbstract
Data on chlorophyll - a contents in algae (open waters) obtained using Sentinel - 3 satellite images, for days close to the equinoxes and solstices in the 2022 – 2025 years, highlighted that the coastal area in the western Black Sea is slightly affected by eutrophication. In the studied area – Musura Gulf and the coastal zone from the shore to approximately 5 km offshore of the Black Sea, between the southern breakwater of the Sulina Channel and the mouth of the Saint George Branch – overall, chlorophyll - a concentrations values ranging from 0.02 – 2.00 μg/L were recorded. The highest values of the mean chlorophyll - a contents were identified in the day close to the summer solstice of 2024 (1.78 μg/L) in the coastal area, as well as in the day close to the spring equinox of 2025 (1.63 μg/L) in the Musura Gulf. The lowest value of the mean chlorophyll - a contents recorded in the Musura Gulf was 0.92 μg/L, in the day close to the winter solstice of 2025, and in the coastal area, 0.69 μg/L, in the days close to the winter solstice of 2024 and 2025. Therefore, the Black Sea waters in the mentioned days are classified as ultra - and oligotrophic.
References
Degens, E.T., & Ross, D.A. (1974). The Black Sea – Geology, Chemistry and Biology. In: Degens, E. T., Ross, D. A., Eds., American Association of Petroleum Geologists: Memoir 20, American Association of Petroleum Geologists, Tulsa, Oklahoma, U.S.A., 633 pp. https://doi.org/10.4319/lo.1974.19.6.1016
Murray, J.W. (1991). Black Sea Oceanography: Results from the 1988 Black Sea Expedition: Introduction and summary. Deep - Sea Research Part A. Oceanographic, 38, S661 - S665. https://doi.org/10.1016/s0198 - 0149(10)80002 - 0
Mutihac, V., & Mutihac, G. (2010). The geology of Romania in the Central - East - European geostructural context. Ed. Didactică și Pedagogică , Bucharest, 648 pp. (in Romanian).Acheampong, C. (2018). Deriving algal concentration from Sentinel - 2 through a downscaling technique for algal bloom monitoring: a case near the intake of a desalination plant. PhD thesis, 1 – 53.
BSC (2008). State of the Environment of the Black Sea (2001 – 2006/7), edited by Temel Oguz, Publications of the Commission on the Protection of the Black Sea Against Pollution (BSC) 2008 - 3, Istanbul, Turkey, 448 pp.
Grégoire, M., Alvera - Azcaráte, A., Buga, L., Capet, A., Constantin, S. et al. (2023). Monitoring Black Sea environmental changes from space: New products for altimetry, ocean colour and salinity. Potentialities and requirements for a dedicated in - situ observing system. Frontiers in Marine Science, 9, 1 – 21.
https://doi.org/10.3389/fmars.2022.998970
Bodík, I. (2006). Wastewater treatment in the postcommunist Danube River Basin. In: The Environment and Sustainable Development in the New Central Europe, 167 – 182. https://doi.org/10.2307/j.ctt9qcjc1.17
Frîncu, R. - M. (2021). Long - Term Trends in Water Quality Indices in the Lower Danube and Tributaries in Romania (1996 - 2017). International Journal of Environmental Research and Public Health, 18 (1665), 1 – 16. https://doi.org/10.3390/ijerph18041665
Halder, J., Vystavna , Y., & Wassenaar, L.I. (2022). Nitrate sources and mixing in the Danube watershed: implications for transboundary river basin monitoring and management. Scientific Reports, 12(2150), 1 – 9.
https://doi.org/10.1038/s41598 - 022 - 06224 - 5
Lancelot, C., Staneva, J., Van Eeckhout , D., Beckers, J. - M., & Stanev, E. (2002). Modelling the Danube - Influenced North - Western Continental Shelf of the Black Sea. II: Ecosystem Response to Changes in Nutrient Delivery by the Danube River after Its Damming in 1972. Estuarine, Coastal and Shelf Science, 54, 473 – 499. https://doi.org/10.1006/ecss.2000.0659
Reschke, S., Ittekkot, V., & Panin, N. (2002). The Nature of Organic Matter in the Danube River Particles and North - western Black Sea Sediments. Estuarine, Coastal and Shelf Science, 54, 563 – 574.
https://doi.org/10.1006/ecss.2000.0665
Ajeagah, G.A., Cioroi, M., Praisler, M., Constantin, O., Palela, M., & Bahrim, G. (2013). An Ecological Assessment of the Pollution Status of the Danube River Basin in the Galati Region — Romania. Journal of Water Resource and Protection, 5, 876 – 886. https://doi.org/10.4236/jwarp.2013.59089
Diaz, R.J., & Rosenberg, R. (2008). Spreading Dead Zones and Consequences for Marine Ecosystems. Science, 321, 926 – 929. https://doi.org/10.1126/science.1156401
Turner, A.M., & Chislock, M.F. (2010). Blinded by the stink: nutrient enrichment impairs the perception of predation risk by freshwater snails. Ecological Applications, 20(8), 2296 – 2302. https://doi.org/10.1890/10 - 0208.1
Uyar, N., Marangoz, A.M., Kocabaş, S., Mutlu, S., & Atabay, H. (2023). Detection of chlorophyll a on the Black Sea Coast with Sentinel - 2 Satellite. International Journal of Chemistry and Technology, 7(1), 48 – 56.
https://doi.org/10.32571/ijct.1201634
Vollenweider, R.A., Giovanardi, F., Montanari, G., & Rinaldi, A. (1998). Characterization of the trophic conditions of marine coastal waters with special reference to the NW Adriatic Sea: proposal for a trophic scale, turbidity and generalized water quality index. Environmetrics, 9, 329 – 357.
Gitelson, A.A., Gurlin, D., Moses, W.J., & Yacobi , Y.Z. (2011). Remote Estimation of Chlorophyll - a Concentration in Inland, Estuarine, and Coastal Waters. In: Weng, Q. (Ed.), Advances in Environmental Remote Sensing: Sensors, Algorithms, and Applications. CRC Press, 18, 439 – 468. https://doi.org/10.1201/b10599 - 27
Nikitine, B. (1925). The biological conditions of the Black Sea observed in 1923 – 25. Nature, 116, 863.
https://doi.org/10.1038/116863b0
Acheampong, C. (2018). Deriving algal concentration from Sentinel - 2 through a downscaling technique for algal bloom monitoring: a case near the intake of a desalination plant. PhD thesis, 1 – 53.
OECD (Organization for Economic Cooperation and Development) (1982). Eutrophication of Waters, Monitoring, Assessment and Control. OECD Publication, Paris, 154 pp.
https://doi.org/10.1002/(sici)1099 - 095x(199805/06)9:3<329::aid - env308>3.0.co;2 - 9
Vuță, L.I., & Dumitran , G.E. (2013). Assessment of water quality at the Romanian Black Sea shore. U.P.B. Scientific Bulletin, Series D: Mechanical Engineering, 75(2), 195 – 206.
