EBRU YEŞİM ÖZKAN, HASAN BAHA BÜYÜKIŞIK, Tufan KORAY, FATMA SABANCI

The İnfluence of changes in nutrient ratios on several biological processes in Inner Bay of Izmir

The dilution method was employed in Inner Bay of Izmir in order to measure the phytoplankton community potential growth rate and grazing rate in May 2005. In this study, the percentage of primary production consumed via grazing and the significance of grazing in food chain were emphasized. The dilution technique was studied on the natural sea water enriched with various Si:N and N:P ratios. Nitrogen limitation was observed in Si:N experiment series. The consumed percentage of primary production via grazing increased with the rising Si:N ratio while the grazed percentage of biomass was decreased. The net growth rate of phytoplankton was greater than the grazing rate at a Si:N ratio of 0.34 and 1.31. For greater ratios, grazing rate became higher than the net growth rate. From the data obtained, it was concluded that microplankton is able to keep the size of the algal populations around the steady state. The Si:N ratio in İzmir Bay is approximately 6 on May 18, 2005. Because of the nitrogen treatment that tends to increase this ratio in the sea water, microzooplankton grazing must limit phytoplankton blooms. The changes in Si:N ratios can account for the 83-98% of the taxon-specific grazing. Prorocentrum gracile, Cylindrotheca closterium and picoplankton were the most abundant species observed constantly both in Si:N ratio and N:P ratio series. Quite few and negative in situ growth rates revealed that nutrient limitation was also of great significance besides grazing on phytoplankton. The N:P ratio of 4 in the environment indicated that Prorocentrum gracile and Cylindrothece closterium would be consumed via grazing and picoplankton would be under pressure by nutrient limitation.

Anahtar Kelimeler:

fitoplankton, Türkiye, fizikokimyasal özellikler, deniz suyu, İzmir

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Basoglu, Ş. 1975. Hydrography and Sedimentology in Inner Part of Izmir Bay, PhD. thesis, İzmir: Ege University, 85 pp.

Berland, B.R., Maestnni, S.Y. and Grzebyk, D. 1995. Observations on possible life cycle stages of the dinoflagellates Dinophysis cf. acuininata, Dinophysis acuta and Dinophysis pavillardi. Aquat. Microb. Ecol., 9: 183-189.

Büyükışık, B. 1986. Comparative studies on nutrient dynamics in Izmir Bay (Inner Bay and Gülbahçe Bay). PhD. thesis, Izmir: Ege University.

Büyükışık, B. and Erbil, Ö. 1987. Researches’ on nutrient dynamics of İzmir Inner Bay, Doğa Tu. Müh. ve Çev. D.C., 11(3): 379-395.

Büyükışık, B., Sunlu, U., Sunlu, S., Sever, T.M., Kükrer, S., Orçun, E., Aydın, A., Köksal, Y., Yürür, E., Ergun, M. and Gençay, H. 2003. Measurements of phytoplankton community growth-rate and zooplankton grazing-rate via dilution method in İzmir Inner Bay. XII. National Fisheries Symposium, Reports release, Elazığ.

Estrada, M., Berdalet, E., Marrase, C., Arin, L. and MacLean, M.L. 1996. Effect of different nutrient combinations on phytoplankton development in microcosms. Intergovernmental Oceanographic Commission, UNESCO, Paris: 297-300.

Frost, B.W. 1972. Effects of size and concentration of foodparticles on the feeding behavior of the marine planktonic copepod Calanus pacificus. Limnol. Oceanogr., 17(6): 805-815.

Gallegos, C.L., Vant, WN. and Safi, K.A. 1996. Microzooplankton grazing of phytoplankton in Manukau Harbour, New Zealand. NZ. J. Mar. Freshwater Res., 30: 423–434.

Gaul, W. and Antia, A.N. 2001. Taxon-specific growth and selective microzooplankton grazing of phytoplankton in the Northeast Atlantic, Journal of Marine Systems, 30: 241-261.

Guillard, R.R.L. 1973. Handbook of Phycological Methods- Culture Methods and Growth Measurements. In: J.R. Stain (Ed.), Cambridge University Press, USA, 311 pp.

Hodkiss, I.J. and Ho, K.C. 1997. Are changes in N:P ratios in coastal waters the key to increased red tide blooms? Hydrobiologica, 352: 141-147.

Ignatiades, L., Psarra, S. and Zervakis, V. 2002. Phytoplankton size-based dynamics in the Aegean Sea (Eastern Mediterranean), J. Mar. Syst., 36: 1-2.

Krom, M.D., Kress, N., Brenner, S. and Gordon, L.I. 1991. Phosphorus limitation of primary productivity in the eastern Mediterranean Sea, Limnol. & Oceanogr. 36: 424-432.

Krom, M.D., Brenner, S., Kress, N., Neori, A. and Gordon, L.I. 1992. Nutrient dynamics and new production in a warm-core eddy from the eastern Mediterranean Sea. Deep-Sea Res., 39: 467-480.

Küçüksezgin, F., Kontaş, A., Altay, O. and Uluturhan, E. 2005. Elemental composition of particulate matter and nutrient dynamics in the Inner Bay (Eastern Aegean). Journal of Marine Systems, 56: 67-84.

Landry, M.R. and Haset, R.P. 1982. Estimating the grazing impact of marine microzooplankton. Mar. Biol., 67: 283-288.

Landry, M.R., Kirshtein, J. and Constantinou, J. 1995. A refined dilution technique for measuring the community grazing impact of microzooplankton, with experimental tests in the central aquatorial Pacific, Mar. Ecol. Prog. Ser., 120: 53-63.

Landry, M.R., Constantinou, J., Latasa, M., Brown, S.L., Bidigare, R.R. and Ondrusek, M.E. 2000. Biological response to iron fertilization in the eastern equatorial Pacific (IronExII). III. Dynamics of phytoplankton growth and microzooplankton grazing. Mar. Ecol. Prog. Ser., 201: 57-72.

Lorenzen, C.J. 1966. A method for the continuous measurement of the in vivo chlorophyll concentration. Deep Sea Res., 13: 223-227.

Madden, C.J. and Day, Jr. J.W. 1992. An instrument system fort he high-speed mapping of chlorophyll-a and physico-chemical variables in surface waters. Eustaries., 15(3): 421-427.

Martin, D.F. 1972. Marine Chemistry, Vol. 1, Analytical Methods, Marcel Dekker Inc., New York, 389 pp.

Officer, C.B. and Ryhter, J.H. 1980. The possible importance of silicon in marine eutrophication. Mar. Ecol. Prog. Ser., 3: 83-91.

Pearl , H.W. 1997. Coastal eutrophication and harmful algal blooms: importance of atmospheric deposition and groundwater as “new” nitrogen and other nutrient sources. Limnol.& Oceanogr., 42(5-2): 1154-1165.

Redfield, A.C., Ketchum, B.H. and Richards, F.A. 1963.The influence of organisms on the composition of seawater. In: M.N. Hill (Ed.), The sea, ideas and observations on progress in the study of the seas, Interscience, NY: 26-77.

Paranjape, M.A. 1990. Microzooplankton herbivory on the Grand Bank (Newfounland, Canada): a seasonal study, Marine Biology, 107: 321-328.

Parsons, T.R., Maita, Y. and Laslli, C.M. 1984. A manual of chemical and biological methods for sea water analysis. Pergamon Press, NY., 173 pp.

Sommer, U. 1987. Factors controlling the seasonal variation in phytoplankton species composition-A case study for a deep nutrient-rich lake. Prog. Phycol. Res., 5: 124-178.

Sterner, R.W. 1985. The role of grazers in phytoplankton succestion, In: U. Sommer (Ed.), Plankton Ecology, Springer-Verlag, Berlin: 107-170.

Strickland, J.D.H. and Parsons, T.R. 1972. A Practical Handbook of Seawater Analysis, Bull. No. 167, Fisheries Research Board of Canada, Ottawa, 310 pp.

Strom, S.L. and Welschmeyer, N.A. 1991. Pigment-specific rates of phytoplankton growth and microzooplankton grazing in the open subarctic Pacific Ocean. Limnol& Oceanogr., 36: 50-63.

Sunlu, U., Büyükışık, B., Koray, T., Bröckel, K.V., Sunlu, S., Sever, M., Aydın, H., Aksu, M., Aydın, A. and Orçun, E. 2006. Impacts of the activation of Big Channel Project on the lower nutritional levels in waters of İzmir Bay, 102Y116 TÜBITAK-YDABAG Project.

Suttle, C.A. and Harrison, P.J. 1988. Ammonium and phosphate uptake rates, N:P supply ratios and evidence for N and P limitation in some oligotrophic lakes. Limnol and Oceanogr., 33: 186-202.

Tilman, D., Kiesling, R., Kilham, S.S. and Johnson, F.A. 1986. Green, blue-green and diatom algae: taxonomic differences in competitive ability for phosphorus, silicon and nitrogen. Arch Hydrobiol., 106: 473-485.

Tselopides, A., Zervakis, V., Polychronaki, T., Danovaro, R. and Chronis, G. 2000. Distribution of nutrients and particulate organic matter in relation to the prevailing hydrographic features of Cretan Sea (NE Mediterranean). Prog. Oceanogr., 46: 113-142.

Verity, P.G., Wassmann, P., Frischer, M.E., Howard Jones, M.H., Allen, A.E. 2002. Grazing of phytoplankton by microzooplankton in the Barents Sea during early summer, Journal of Marine Systems, 38: 109-123.

Wood, R.D. 1975. Hydrobotanical Methods. University Park Press, Baltimor, 173 pp.