Evaluation of seasonal physicochemical conditions and chlorophyll-a concentrations in Izmit Bay, Marmara Sea
Halim Aytekin Ergül
Department of Biology, Faculty of Science and Literature, Kocaeli University, 41380 Kocaeli, TURKEY
Vertical and horizontal gradient of temperature, salinity, density, chlorophyll-a, dissolved oxygen and pH were monitored seasonally between summer 2008 and spring 2010 in the eastern, central and western basins of Izmit Bay (Marmara Sea). Surface seawater temperature ranged from 7.5 to 26 °C during the study period. Thermal stratification was found to be significant in winter and summer. Surface water salinity ranged from 20.9 to 24.0 ‰ in summer 2008 and 2009 and reached up to 36.1 ‰ below halocline layer. Permanent pycnocline and a two-layered stratification were observed throughout the study. Sigma-t seasonally varied between 13.5 and 18.4 in the upper layer and increased up to 27.2 by increasing depth below the intermediate layer. Average seasonal Chl-a concentrations ranged from 1.5 in summer 2008 to 9.6 μg L-1 in spring 2010. The highest average Chl-a concentrations was found in the eastern basin during the study, whereas the maximum Chl-a level was measured as 18 μg L-1 in the central basin in spring 2010. Higher DO concentrations were measured in the western basin while the lowest (i.e., 0.2 mg L-1) was measured in the eastern basin located near the densely populated city center of the Kocaeli Province. Hypoxic conditions occurred in the intermediate layer in summer seasons while it was routinely present in the lower layer. Meteorological conditions impact the oceanography of the bay. In summer 2009, warm air temperature, weak wind speed, accordingly weak vertical water mixing accompanied with warm surface water resulted near surface hypoxia (i.e., below 4 m from the surface) in the eastern basin of Izmit Bay.
Keywords: Izmit Bay, Marmara Sea, chlorophyll-a, hypoxia, wind speed
Aksu, A., Balkis, N., Taşkin, Ö., Erşan, M. (2011) Toxic metal (Pb, Cd, As and Hg) and organochlorine residue levels in hake (Merluccius merluccius) from the Marmara Sea, Turkey. Environmental Monitoring and Assessment 182(1): 509-
Aktan, Y., Tüfekçi, V., Tüfekçi, H., Aykulu, G. (2005) Distribution patterns, biomass estimates and diversity of phytoplankton in İzmit Bay (Turkey). Estuarine, Coastal and Shelf Science 64(2–3): 372-384.
Algan, O., Altiok, H., Yuce, H. (1999) Seasonal variation of suspended particulate matter in two-layered Izmit Bay, Turkey. Estuarine Coastal and Shelf Science 49(2): 235-250.
Anatolian-Agency (2001) Fish mortality in the Gulf of Izmit.
Balkis, N. (2003) The effect of Marmara (Izmit) Earthquake on the chemical oceanography of Izmit Bay, Turkey. Marine Pollution Bulletin 46(7): 865-878.
Balkis, N., Senol, E., Aksu, A. (2007) Trace metal distributions in water column and surface sediments of Izmit Bay (Turkey) after Marmara (Izmit) earthquake. Fresenius Environmental Bulletin 16(8): 910-916.
Besiktepe, S.T., Sur, H.I., Ozsoy, E., Latif, M.A., Oguz, T., Unluata, U. (1994) The Circulation and Hydrography of the Marmara Sea. Progress in Oceanography 34(4): 285-334.
Ergül, H.A., Aksan, S. (2013) Evaluation of non-essential element and micronutrient concentrations in seafood from the Marmara and Black Seas. J. Black Sea/Mediterranean Environment 19(3): 312˗330.
Ergül, H.A., Belivermiş, M., Kılıç, Ö., Topcuoğlu, S., Çotuk, Y. (2013) Natural and artificial radionuclide activity concentrations in surface sediments of Izmit Bay, Turkey. Journal of Environmental Radioactivity 126:125-132.
Fisher, N.S., Reinfelder, J.R. (1995) The trophic transfer of metals in marine systems (Metal speciation and bioavailability in aquatic systems). New York: Wiley.
Fofonoff, P., Millard, R.C. (1983) Algorithms for computation of fundamental properties of seawater. Unesco Technical Papers in Marine Sciences 44: 53 pp.
Gündüz, M., Özsoy, E. (2015) Blocking of the upper layer flow in the Çanakkale (Dardanelles) Strait and its influence on fish catches. J. Black Sea/Mediterranean Environment 21(3): 13.
Karademir, A., Ergül, H.A., Telli, B., Kilavuz, S.A., Terzi, M. (2013) Evaluation of PCDD/F pollution in surface sediments of Izmit Bay. Environmental Science and Pollution Research 20(9): 6611-6619.
Kuscu, I., Okamura, M., Matsuoka, H., Awata, Y. (2002) Active faults in the Gulf of Izmit on the North Anatolian Fault, NW Turkey: a high-resolution shallow seismic study. Marine Geology 190(1-2): 421-443.
Küçük, A., Ergül, H.A. (2011) Seasonal variations of microplankton composition in İzmit Bay (Sea of Marmara). J. Black Sea/Mediterranean Environment 17(3): 216-222.
Mol, S., Doğruyol, H. (2012) The Effect of Climate Change on Seafood and their Consumption. Journal of FisheriesSciences 6(4): 341-356.
Morkoc, Tugrul, S., Okay, O. S., Legovic, T. (1997) Eutrophication of the Izmit bay, Marmara Sea. Croatica Chemica Acta 70(1): 347-359.
Morkoç, E., Tarzan, L., Okay, O., Tufekci, H., Tufekci, V., Tolun, L. (2007) Changes of oceanographic characteristics and the state of pollution in the Izmit bay following the earthquake of 1999. Environmental Geology 53(1): 103-112.
Oguz, T., Sur, H.I. (1986) A numerical modelling study of circulation in the Bay of Limit: Final Report. TUBITAK-MRI, Chemistry Department Publication, Gebze-Kocaeli, Turkey. 187-197 pp.
Okay, O.S., Tolun, L., Telli-Karakoc, F., Tufekci, V., Tufekci, H., Morkoc, E. (2001) Izmit Bay (Turkey) ecosystem after Marmara earthquake and subseqnent refinery fire: the long-term data. Marine Pollution Bulletin 42(5): 361-369.
Strickland, J.D.H., Parsons, T.R. (1988) A Practical Handbook of Seawater Analysis. Ottawa: Fisheries Research Board of Canada.
Tolun, L., Martens, D., Okay, O.S., Schramm, K.W. (2006) Polycyclic aromatic hydrocarbon contamination in coastal sediments of the lzmit Bay (Marmara Sea): Case studies before and after the Izmit Earthquake. Environment International 32(6): 758-765.
Tugrul, S., Polat, C. (1995) Quantitative comparison of the influxes of nutrients and organic-carbon into the sea-of-Marmara both from anthropogenic sources and from the Black-Sea. Water Science and Technology 32(2): 115-121.
Ünlüata, Ü., Oğuz, T., Latif, M.A., Özsoy, E. (1990) On the Physical Oceanography of the Turkish Straits. In: The Physical Oceanography of Sea Straits (ed. L. J. Pratt), Netherland: Kluwer Academic Publishers. pp. 25-60.