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Winter versus summer blooming of phytoplankton in a shallow lake: effect of hypertrophic conditions

Toporowska M., Pawlik-Skowrońska B., Krupa D., Kornijów R.

Polish Journal of Ecology

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2010

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Vol. 58, nr 1

3-12

EN

The comparison of species richness, abundance and diversity of phytoplankton blooms, which developed both in winter and summer seasons as an effect of lake hypertrophy, was the aim of this study. In the ice-covered lake (0.30 mg PO[4]-P L[^-1], 1.35 mg NH[4]-N L[^-1]; TSI[SD] = 64; TSI[chl] = 93), the algal bloom, responsible for high concentration of dissolved oxygen in water, consisted mainly of the centric diatom Stephanodiscus minutulus (3.9 x 10[^7] ind. L[^-1]) accompanied by Limnothrix redekei (Cyanobacteria), Koliella longiseta (Chlorophyceae), > 1.1 x 10[^6] ind. L[^-1] each, as well as Mallomonas sp. (Chrysophyceae) and Monoraphidium komarkovae (Chlorophyceae), >5.0 x 10[^5] ind. L[^-1] each. The toxic cyanobacterium Planktothrix agardhii of extremely long trichomes (up to 0.93 mm) and potentially toxic dinoflagellate Peridinium aciculiferum f. inerme occurred also in high numbers (1.9 x 10[^5] ind. L[^-1] and 7.7 x 10[^4] ind. L[^-1], respectively). In summer (0.05 mg PO[4]-P L[^-1]; 0.42 mg NH[4]-N L[^-1]; TSI[SD] = 78; TSI[chl] = 102), the phytoplankton bloom consisted of P. agardhii (average total abundance 49.4 x 10[^6] ind. L[^-1]) and ten other taxa of Cyanobacteria, Bacillariophyceae, Chlorophyceae and Cryptophyceae (average total abundance 17.9 x 10[^6] ind. L[^-1]). The total phytoplankton abundance was 1.5 times higher in summer than in winter and the total biomass of the most abundant species was approximately 4 times higher in warm (139.8 mg L[^-1]) than in cold season (32.5 mg L[^-1]). The values of the Shannon-Weaver diversity index were very low, however, over 2 times higher in summer (0.60) than in winter (0.31). The obtained results revealed that in the hypertrophic lake the very high nutrient concentrations (especially NH[4]-N and PO[4]-P), found both in winter and summer, were responsible for year-long mass development of phytoplankton. The winter phytoplankton was composed mainly of very small centric diatoms, whereas summer blooms were created by filamentous cyanobacteria (mainly Oscillatoriales; 98%).

2

Phosphorus release from the bottom sediments of Lake Rusałka (Poznań, Poland)

Kowalczewska-Madura K., Gołdyn R., Dondajewska R.

Oceanological and Hydrobiological Studies

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2010

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Vol. 39, No.4

135-144

EN

Experimental research conducted on bottom sediments from the eutrophic Lake Rusałka (Poznań, Poland) indicated that the phosphorus release process has a significant influence on the functioning of the ecosystem. Internal loading was very intense in the deepest part of the lake, where it reached up to 29.84 mg m^-2 d^-1 P under anaerobic conditions. This part of the lake, however, was insignificant to overall internal loading. The highest loading was from the lake shallows, which covered 92% of the bottom area. Total mean annual loading to the ecosystem was 1214.5 kg year^-1 P, i.e., 3.31 g m^-2 year^-1 P.

3

Influence of type of substrate and water chemistry on the structure and succession of periphytic ciliate communities in hypertrophic lake

Mieczan T., Puk A.

Archives of Environmental Protection

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2010

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Vol. 36, no. 2

13-24

EN

The aims of the study was to establish whether differences exist between periphytic ciliate communities on different substrates; to determine whether colonization time would yield an abundance and taxonomic composition of ciliates; to assess the effect of physical and chemical factors on the distribution of ciliates in a shallow hypertrophic lake. Generally the species richness as well as the abundance of periphytic ciliates are determined mostly by the habitats and chemical properties of the waters (especially the content of total organic carbon and nitrate nitrogen), and, to a lesser extent, by the type of the colonized substrate. Moreover, exposition time of the substrates affected both an increase in the richness of periphytic ciliates and the changes in their trophic structure. At the beginning of the experiment the substrates were intensively colonized by typically bacterivorous species, yet prolonged exposition time resulted in an increasing proportion of omnivorous species.

PL

Celem pracy było porównanie składu taksonomicznego i liczebności zespołu orzęsków peryfitonowych zasiedlających różne podłoża; określenie, w jaki sposób czas ekspozycji podłoży wpływa na obfitość tych mikroorganizmów oraz analiza zależności pomiędzy wybranymi właściwościami fizyczno-chemicznymi wód a orzęskami w jeziorze hypertroficznym. Wykazano, że zarówno bogactwo gatunkowe jak i obfitość orzęsków peryfitonowych w największym stopniu determinują zasoby pokarmowe siedliska oraz właściwości chemiczne wód (głównie zawartość całkowitego węgla organicznego oraz azotu azotanowego), w mniejszym zaś stopniu rodzaj kolonizowanego podłoża. Czas ekspozycji podłoży wpływał zarówno na wzrost obfitości peryfitonowych orzęsków jak i zmianę ich struktury troficznej. Na początku eksperymentu podłoża były intensywnie kolonizowane przez gatunki typowo bakteriożerne, wraz ze wzrostem czasu ekspozycji podłoży wzrastał udział gatunków wszystkożernych.