Hidrológiai Közlöny 2010 (90. évfolyam)

6. szám - LI: Hidrobiológus Napok: „Új módszerek és eljárások a hidrobiológiában” Tihany, 2009. szeptember 30–október 2.

133 Malinsky-Rushansky, N„ T. Berman & Z. Dubinsky (1995) Seasonal dynamics of picophytoplankton in Lake Kinneret, Israel. - Freshwater Biol. 34: 241-254. 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. Pick, F. R. & D. M. Agbeti (1991) The seasonal dynamic and composition photosynthetic picoplankton communities in temperate lakes in Ontario, Canada. - Int. Revue ges. Hydrobiol. 76: 565-580. Somogyi B. & Vörös L. (2006) A pikoplankton fotoszintézisének karakterisztikái sekély tavakban. - Hidroógiai Közöny 86: 110-112. Somogyi, B.. Felföldi, T., Vanyovszki, J„ Agyi, A., Márialigeti, K. & Vörös, L. (2009) Winter bloom of picoeukaryotes in extremely shallow turbid soda lakes. - Aquat. Ecol. 43:735-744. Steemann-Nielsen, E. (1952) The use of radioactive carbon (C-14) for measuring organic production in the sea. - J. Const. Int. Explor. Mer. 18: 117-140. Stockner, J. G. & Antia, N. J. (1986) Algal picoplankton from marine and freshwater ecosystems: a multidisciplinary perspective. - Can. J. Fish. Aquat. Sei. 43:765-775. Vörös L. (1989) A pikoplankton jelentősége a Balatonban. - Hidrológiai Közlöny 69:321-327. Vörös, L. (1991) Importance of picoplankton in Hungarian shallow lakes. - Verh. Internat. Verein. Limnol. 24:984-988. Vörös, L., Mózes, A. & Somogyi, B. (2009) A five-year study on the phototrophic winter picoplankton in a large shallow lake (Lake Balaton, Hungary) - Aquat. Ecol. 43:727-734. Wetzel R G. & G.E. Likens (1991) Limnological Analyses. 2nd Ed. SpringerVerlag New York. 391 pp. The importance of picophytoplankton in Lake Balaton in winter B. Somogyi, A. Kiirthy , B. Németh' and L. Vörös' 'Balaton Limnological Research Institute of the HAS, Tihany - 2University of Debrecen, Debrecen Abstract: Primary production measurements in shallow lakes are mainly confined to the productive periods of the year. In winter, low temperature and irradiance restrict surely the algal growth; however the appearance of several algal groups (mainly picoeukaryotic algae) has been indicated in the temperate zone in winter. In this study, we determined the primary production of the total phytoplankton in Lake Balaton in February and June 2009. The contribution of the picoplankton fraction (<3 pm) to the total primary production was also determined. The photosynthesis of the total phytoplankton and the picoplankton was measured using 1

4C method in a photosynthetron under 10-1200 pmol m'

2 sec ' irradiance range. On the basis of the experimentally obtained photosynthesis/irradiance curves we determined the photosynthetic parameters (P

m

ax, Ik, a) of the size fractions and the surface-related planktonic primary production was calculated. The contribution of the picoplankton to the total primary production was 52 % in the Keszthely-basin and 24 % in the Siófok-basin. Their contribution showed diurnal and depthdependence variation in connection with the changing irradiance. The importance of the picoplankton in the primary production in Lake Balaton was similarly high in winter than in summer. Keywords: primary production, picoplankton, nanoplankton (Klossy Irén alkotása)