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1
Content available remote Vertical distribution of phototrophs in the pelagic zone of three small Lobelia lakes
Szeląg-Wasielewska E.
Oceanological and Hydrobiological Studies
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2010
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Vol. 39, No.2
121-133
EN
The community structure and biomass of pelagic phototrophs, with a particular focus on the picoplanktonic fraction, were studied in three small, soft-water lakes in the Pomerania Lake District (north Poland). The smallest phototrophs were usually dominated by picocyanophytes, both single-celled and colonial. Picochlorophytes were less frequent, and they formed dense populations only in one lake. The nano- and microplankton included many groups of organisms, but the main groups were comprised of dinoflagellates, chrysophytes and chroococcoid and/or filamentous cyanophytes and large raphidophytes. Community structure changed significantly with depth and in all lakes remarkable differences were observed between the epilimnion and both the meta- and hypolimnion. The hypolimnion was characterized by the presence of photosynthetic green sulfur bacteria or their symbiotic consortia.
2
Content available remote Functioning of the Lake Rusałka ecosystem in Poznań (western Poland)
Gołdyn R., Szeląg-Wasielewska E., Kowalczewska-Madura K., Dondajewska R., Budzyńska A., Podsiadłowski S., Domek P., Romanowicz-Brzozowska W.
Oceanological and Hydrobiological Studies
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2010
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Vol. 39, No.3
65-80
EN
Lake Rusałka is a shallow, artificial, strongly eutrophic reservoir. Thermal stratification is weak and comprises only about 8% of the bottom surface. In summer, the epilimnion is oversaturated with oxygen due to intensive phytoplankton growth (chlorophyll a up to 80.2 μg l^-1), while conditions in the hypolimnion are anaerobic. The high concentration of ammonium nitrogen and low N:P ratio stimulated intense growth of cyanobacteria in the period from June to November. The domination of rotifers in the metazooplankton and low diversity and biomass of benthic macroinvertebrates was the cause of low top-down pressure of these organisms on the phytoplankton. The most advantageous restoration measures were identified to improve water quality and make the recreational use of the lake possible.
3
Content available remote Auto- and heterotrophic picoplankton in a lowland river (Warta River, Poland)
Szeląg-Wasielewska E., Stachnik W.
Oceanological and Hydrobiological Studies
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2010
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Vol. 39, No.1
137-146
EN
The structure of plankton in a lowland river was studied with a particular focus on autotrophic as well as heterotrophic picoplankton cells. Water samples were collected in the middle, meridional section of the Warta River in 2005. Heterotrophic picoplankton (HPP) were represented by bacteria varying in size and form, but mainly by cocci and rods. HPP abundance ranged from 3.5 × 10^6 to 9.5 × 10^6 cells m1^-1. Autotrophic picoplankton (APP) densities were considerably lower and ranged from 1.2 × 10^3 to 92 × 10^3 cells ml^-1. They were represented by prokaryotes (picocyanobacteria) and eukaryotes (small chlorophytes). Both components occurred together but eukaryotic APP usually prevailed in terms of biomass. In terms of biomass, APP seemed to play a minor role in this ecosystem in comparison with heterotrophic picoplankton.
4
Content available remote Trophic state assessment based on late summer phytoplankton community structure: a case study for epilimnetic lake water
Szeląg-Wasielewska E.
Oceanological and Hydrobiological Studies
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2007
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Vol. 36, No.3
53-63
EN
Phytoplankton species composition, abundance and biomass were studied in samples taken from the epilimnion of Lake Strzeszyńskie in late August of each year from 2000-2005. The number of phytoplankton species was relatively low, with the greatest species diversity observed in the Chlorophyceae. Total phytoplankton abundance was high, with major contributions by picophytoplanktonic cyanobacteria, which formed aggregations. Total phytoplankton biomass was generally low, with the sum of the 2-5 biomass-dominant species always exceeding 50% of the total phytoplankton biomass. The taxonomic composition of the group of biomass dominants was relatively stable inter-annually. On the basis of phytoplankton biomass and chlorophyll a concentration, Lake Strzeszyńskie can be classified as oligo-mesotrophic and mesotrophic respectively. Trophic index values calculated on the basis of abundance of phytoplankton indicator taxa were higher than the values based on their biomass, and mean values indicate that the lake is mesotrophic or intermediate between mesotrophic and eutrophic.
5
Content available remote The smallest phototrophic organisms in a lowland river: comparison with other components of the phytoseston
Szeląg-Wasielewska E.
Oceanological and Hydrobiological Studies
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2004
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Vol. 33, No. 4
61--72
EN
The phytoseston of the Warta, a polluted eutrophic river in western Poland, was studied from spring to autumn 2003. The focus of the study was autotrophic picoplankton (APP). APP abundance fluctuated from 1.3×10sup>6 to 1.05×10sup>8cells Lsup>-1 and was characterized by a maximum in late July. APP biomass was low, ranging from 0.5 to 19.7μg C Lsup>-1. Both cyanobacteria and eukaryotic organisms were found within the picoplankton. The picocyanobacterial community was often dominated by colonial forms, mostly Aphanocapsa spp. and Cyanogranis ferruginea (Wawrik) Hindák. Eukaryotic picoplankton included chlorophytes of the genera Chlorella, Choricystis, and Pseudodictyosphaerium jurisii (Hindák) Hindák. Among the phytoplankton larger than 2 μm, the most abundant species were diatoms and chlorophytes, except in late August, when filamentous cyanobacteria dominated. The contribution of APP to the total phytoplankton biomass was usually below 1%, and the mean (0.6%) was close to the lower limit of values found in lakes.
6
Content available remote Changes in the phytoseston of a river-lake system in Drawieński National Park
Gołdyn R., Szeląg-Wasielewska E.
Oceanological and Hydrobiological Studies
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2004
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Vol. 33, No. 2
17--28
EN
The phytoseston in the Płociczna River originated mainly from lakes situated in its water course. It was more abundant and diverse in spring than in summer, which was related to differences in water discharge. The phytoseston abundance between the stations at the inlets and outlets of the successive lakes increased 9.7, 1.9 and decreased 1.4 times, respectively. A gradual reduction in the abundance of organisms was also noted at the outlets of successive lakes, which indicated a decrease in the trophic status of the water. The abundance of phytoseston between the outlets and inlets to the subsequent lakes (river stretch) decreased considerably. Disturbances in the river continuum system caused by the lakes situated in the river course resulted in the acceleration of potamoplankton succession.
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