Seasonal Dynamics of Picocyanobacteria and Picoeukaryotes in a Large Shallow Lake (Lake Balaton, Hungary)

Abstract

The abundance and composition of autotrophic picoplankton (APP) were studied between February 2003 and March 2004 in Lake Balaton. Water samples were taken fortnightly in the eutrophic western basin and mesotrophic eastern basin. Our study, which took more than one year, revealed pronounced seasonal pattern of the picoplankton abundance and composition. According to our results there were three types of picoplankton in Lake Balaton: 1. Phycoerythrin-rich coccoid cyanobacteria (PE), dominant summer picoplankters in the mesotrophic lake area; 2. Phycocyanin-rich cyanobacteria (PC), the most abundant summer picoplankters in the eutrophic lake area; 3. Picoeukaryotes, dominant winter picoplankters in the whole lake. The observed abundance of picoeukaryotes (3 × 10 5 cells ml -1 ) was one of the highest ever found. Our study confirms that in Lake Balaton the colonial autotrophic picoplankton (colonial APP) become dominant in summer in the nutrient limited period. We have found strong negative relationship between the concentrations of available nitrogen forms and the colonial APP abundance. IntroductionSeasonal dynamics of marine and freshwater autotrophic picoplankton (APP) have been reported by several studies (CRAIG, 1984;WEISSE, 1988;STOCKNER, 1991;PICK and AGBETI, 1991;OCHS and RHEW, 1997;MALINSKY-RUSHANSKY et al., 1997;HEPPERLE and KRIENITZ, 2001;JASSER and ARVOLA, 2003), but the factors that regulate their abundance are little known. According to the latest results it seems there is a general trend in the autotrophic picoplankton (APP) dynamics: in the majority of temperate lakes having different depth and trophic state they showed a biphasic distribution.In a four-year study in the meso-to eutrophic Lake Constance WEISSE and KENTER (1991) found that in spring the autotrophic picoplankton (APP) abundance increased with the water temperature until the abundance reached the first maximum in April. Later in May it significantly decreased, and the second peak appeared in late summer, in August. The results reported by CALLIERI and PINOLINI (1995) from the subalpine Lake Maggiore were similar to the results obtained by WEISSE and KENTER (1991). They noticed that the first peak was in April, but the second was later, in late autumn-winter. The seasonality of autotrophic picoplankton (APP) in the shallow and dystrophic Lake Flosek (JASSER, 1997) was biphasic Internat. Rev. Hydrobiol.

Spatio-seasonal variability of chromophoric dissolved organic matter absorption and responses to photobleaching in a large shallow temperate lake

“…In late summer and early autumn, cyanobacterial blooms often occur in the Keszthely basin (I), extending westwards to the Szigliget (II) and Szemes (III) basins and very occasionally to the Sió-fok (IV) basin (Padisak and Reynolds, 1998;Présing et al, 2008;Hajnal and Padisák, 2008). The lowest phytoplankton biomass generally occurs in February when the lake can be ice covered; a small dinoflagellate bloom may also occur in April (Mózes et al, 2006).…”

Periodic picophytoplankton predominance in a large, shallow alkaline lake (Lake Fertő, Neusiedlersee)

“…In shallow mesotrophic lakes the abundance of the picoplankton ranges usually from 10 4 to 10 5 cells.mL x1 (Jasser, 1997;Szelag-Wasielewska, 2003;Mo´zes et al, 2006); however studies on Lake Balaton (Hungary), Lake Fertő (Hungary/Austria) and Lake Sekacz (Poland) describe one magnitude higher values (Vo¨ro¨s, 1989;Padisa´k and Dokulil, 1994;Szelag-Wasielewska, 1997). The contribution of the picoplankton to the total phytoplankton biomass in shallow mesotrophic lakes is usually between 1 and 17% (Vo¨ro¨s, 1989;Jasser, 1997;Szelag-Wasielewska, 1997;Szelag-Wasielewska, 2003).…”

Microcolony Formation by Single-Cell Synechococcus Strains as a Fast Response to UV Radiation

“…in late summer (3). Furthermore, peaks of microcolonies have been observed in summer or autumn in a variety of freshwater system (27,33,38).…”