Hidrológiai Közlöny 2009 (89. évfolyam)

6. szám - L. Hidrológiai Napok: "A hazai hidrobiológia ötven éve" Tihany, 2008. október 1-3.

45 vizében algák számára felvehető nitrogén (ásványi N >1000 pg l-l) és foszfor (P04-P -50 |xg l-l ), szemben a Balatonnal, ahol mindkettő a kimutatási határ közelében van. A viszonylagos tápanyaggazdagság viszont lehet magyarázat arra, hogy a Dunában a kolóniás formák részesedése jelentősen kisebb, mint a nyári hónapokban erősen tápanyag limitált Balatonban. A Dunában a kolóniaképződés a kifalás elleni védelemmel nem hozható összefüggésbe, amint azt már fentebb említettük, a Duna főágában a szűrő zooplankton tömege nagyságrenddel kisebb, mint a tavakban (V.-BALOGH et al. 1994). A mért környezeti paraméterek közül a Dunában legjobban a hőmérséklettel tudtuk összefüggésbe hozni a kolóniás formák megjelenését, mert szignifikáns pozitív korrelációt kaptunk a kolóniás formák részesedése és a vízhőmérséklet között (Pearson-féle korrelációs koefficiens: 0,713; p <0,001

) •APP abundancia T 200 600 • 500 " E 400 • I 300 " N > 200 " 100 CALLIERI, C. and M. L. PINOLINI, 1995: Picoplankton in Lake Maggiore, Italy. - Int. Rev. ges. Hydrobiol. 80: 491-501. DAVIS, L. N, K. A. PHILLIPS and H. G. MARSHALL, 1997: Seasonal abundance of autotrophic picoplankton in the Pagan River, a nutrient enriched subestuary of the James River, Virginia. - Virginia Journal of Science 48: 211-218. FELFÖLDY, L., 1987: A biológiai vízminősítés (4. javított és bővített kiadás). - Vízügyi hidrobiológia. 16, 1-2258. VGI, Budapest. GOLDYN R., E. SZELAG-WASIELEWSKA, I. WEGRZAK, 1999: Autotrophic picoplankton and bacterioplankton in the dam reservoir of Cybina. - [in:] Biological aspects of dam functioning. Proceedings of Phycological Conference, Lublin, September 1999, 55-57. HEPPERLE, D. and L. KRIENITZ, 2001: Systematics and ecology of chlorophyte picoplankton in germán inland waters along a nutrient gradient. - Internat. Rev. Hydrobiol. 86: 269-284. MALINSKY-RUSHANSKY, N., T. BERMAN, Z. DUBINSKY, 1997: Seasonal photosyntetic activity of autotrophic picoplankton in Lake Kinneret, Israel. - J. Plankton Res. 19: 979-993. MÓZES A., PRÉSING M.& VÖRÖS L., 2006: Seasonal dynamics of picocyanobacteria and picoeukaryotes in a large shallow lake (Lake Balaton, Hungary). - Internat. Rev. Hydrobiol. 91: 38-50. MÓZES A., B. SOMOGYI, B. KISS AND L. VÖRÖS, 2008: The contribution of autotrophic picoplankton in lowland rivers and shallow lakes Internat. Rev. Hydrobiol. (submitted). PHILIPS, E. J., S. BADYLAK and T. C. LYNCH, 1999: Blooms of cyanobacterium Synechococcus in Florida Bay, a subtropical inner-shelf lagoon. - Limnol. Oceanogr., 44: 1166-1175. SIN, Y., R. L. WETZEL and I. C. ANDERSON, 2000: Seasonal variations of size-fractioned phytoplankton along the salinity gradient in the York River estuary, Virginia (USA). - Journal of Plankton Res. Vol. 22, no. 10, pp.1945-1960. SZELAG-WASIELEWSKA, E., 2004: The smallest phototrophic organisms in a lowland river: comparison with other components of the phytoseston. - Oceanol. and Hydrobiol. Studies. Vol. XXXIII, No. 4, pp: 61-72. V.-BALOGH, K., A. BOTHAR, K. T. KISS & L. VÖRÖS, 1994: Bacterio-, phyto- and zooplankton of the River Danube (Hungary) Verh. Internat. Verein. Limnol. 25:1692-1694. WATERBURY, J. B„ S. W. WATSON, F. W. VALOIS, and D. G. FRANKS, 1986: Biological and ecological characterization of the marine unicellular cyanobacterium Synechococcus. -Can. Bull. Fish. Aquat. Sci. 214: 71-120. WEISSE, T. and U. KENTER, 1991: Ecological characteristics of autotrophic picoplankton in a prealpine lake. Int. Revue. ges. Hydrobiol. 76: 493-504. WEISSE, T., 1993: Dynamics of autotrophic picoplankton in marine and freshwater ecosystems. - In: Jones JG [ed.] Advances in Microbial Ecology. 13: 327-370. Plénum Press, New York. - v. ~ . ~ » « - , s? <V <$>• sCy Nv Qv 3. ábra. A pikoplankton évszakos dinamikája és a vízállás ingadozása a Duna gödi szakaszán a főágban 2002-2005 között Köszönetnyilvánítás A kutatást az OTKA (K73369) támogatta Irodalom AYUKAI, T., 1992: Picoplankton dynamics in Davies Reef Lagoon, the Great Barrier Reef, Australia. - Journal of Plankton Res. 14: 15931606. BERNARDI AUBRY, F., F. ACRI, M. BASTIANINI, A. PUGNETTI, and G. SOCAL., 2006: Picophytoplankton contribution to phytoplankton community structure in the Gulf of Venice (NW Adriatic Sea). Int. Rev. Hydrobiol. 91:51-70. Seasonal Dynamics of the picoplankton in the River Danube A. Mózes

1, K, T. Kiss

2, L. Vörös

3 'Eötvös Loránd University Faculty of Science, PhD School, Experimentál Plánt Biology, Budapest 2HAS Institute of Ecology and Botany Hungárián Danube Research Station, Göd ^Balaton Limnological Research Institute of the HAS, Tihany Abstract: The abundance and composition of autotrophic picoplankton (APP) were studied biweekly between October 2002 and February 2005 in the main arm of River Danube at Göd (1669 river km) and in its side arm respectively. The picofraction of phytoplankton was determined by epifluorescence microscopy. Our study revealed that the 0.8-1.2 (ím sízed coccoid cyanobacteria were the predominant members of the picoplankton fraction at booth sampling site. Their contribution to the totál picoplankton was 80%. Loose aggregates of 4-6-8 cells were often observed. Phycoerythrin rich cyanobacteria were not found at all. The occurrence and the abundance of picoeukaryotes were low during the investigation period. In the main arm of River Danube the observed totál picoplankton abundance varied between 0.02 1.6 x 10

5 cells ml"

1 with an average of 2.6 x 10

4 cells per milliliter. On the other hand in the side arm of River Danube the APP abundance was higher than in the main arm at each sampling time, i.e. increased from 0.05 cells ml"

1 to 2.3 x 10

5 cells ml"'. Our findings confirmed that in River Danube at Göd the APP contribution to the totál phytoplankton biomass was low, and never reached 5% during the investigation period. Our results demonstrated that in River Danube the seasonal dynamics of the APP was markedly water temperature and water discharge dependent. Key words: picoplankton abundance, seasonal dynamics, water temperature, water discharge