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1

Diatom indices and stream typology in Estonia

100%
Vilbaste S., Jarvekulg R., Pall P., Piirsoo K., Trei T., Viik M.
Oceanological and Hydrobiological Studies
|
2004
|
issue 1
3-10
EN
This paper deals with the use of diatom indices in the assessment of streams in Estonia. The problem addressed is how rational it is to determine different types of streams or stream reaches based on diatom research. At the moment, there are five different typologies of running waters in Estonia, two of which are analyzed here. Diatom indices can be employed to assess the ecological quality of water but not the status or type of stream. The most promising diatom indices for such assessment are the Trophic Diatom Index, Watanabe Index, Descy Index, and Schiefele & Schreiner Index.
2

Effect of different light conditions on cyanobacteria and algal communities in Tatra Mts stream (Pland)

86%
Kawecka B.
|
|
issue 2
3-14
EN
Different light conditions at the open and shaded sites caused by marginal vegetation affected the structure of Cyanobacteria and algae communities, but had no effect on chlorophyll a content. In the open area Hydrurus foetidus (Villars) Trevisan, Homoeothrix janthina (Bornet et Flahault) Starmach, and diatoms (mainly Achnanthes minutissima Kutz. together with A. biasolettiana Grun. and species from the Gomphonema genus ) were the most numerous. In shadow the abundance of Hydrurus foetidus drastically decreased, whereas the diatom biomass index, Achnanthes minutissima and A. biasolettiana showed a tendency to reduce their number. On the contrary, the abundance of green algae and Cocconeis placentula Ehr. var. euglypta Ehr. increased. Chlorophyll a contents of both sites obtaining the highest values in summer - autumn and the lowest in the winter - spring seasons.
3

Water quality study of the Condor and Capivara streams, Porto Alegre Municipal District, Rs, Brazil, using epilithic diatom biocenoses as bioindicators

86%
Lobo E. A., Callegaro V. L. M., Wetzel C. E., Hermany G., Bes D.
Oceanological and Hydrobiological Studies
|
2004
|
issue 2
77-93
EN
The aim of this work was to evaluate the water quality of two urban streams, Condor and Capivara, in the Municipal District of Porto Alegre, RS, Brazil, by measuring physical, chemical and biological variables. Between May 1999 and August 2000, six field trips were taken to sample five sites distributed along the streams. Multivariate canonical correspondence analysis (CCA) was applied for the complete evaluation of physical, chemical and biological data. It was confirmed that phosphate had the largest impact on ordination and exhibited an evident eutrophication gradient. Mayamaea atomus, Amphora montana, Sellaphora pupula and Cyclotella meneghiniana were extremely abundant under such conditions.
4

Response to drying of cyanobacteria and algae communities in Tatra Mts stream (Poland)

86%
Kawecka B.
Oceanological and Hydrobiological Studies
|
2003
|
issue 1
27-38
EN
The structure, dynamics and chlorophyll a content of lithoreophilous communities of Cyanobacteria and algae in two periodically drying sectors of the stream: in its upper (alpine ), and middle part (forest) zones were investigated. In both sectors the diversity of species was low. After snow melt, in the upper part, the stones were successively colonized by Cyanobacteria (with Chamaesiphon polonicus (Rostafinski.) Hansgirg prevailing), and green alga Klebsormidium rivulare (Kutz.) Starmach, finally obtaining stable and abundant communities. In the middle part of the stream, a spring explosion of Klebsormidium rivulare and species from the Chlorococcales group was observed. They developed temporary, since they disappeared after the June spate. Later this area was colonised mainly by Homoeothrix janthina (Bornet et Flahault) Starmach, Hydrurus foetidus (Villars) Trevisan, and diatoms, coming from a neighbouring non drying part of the stream. The chlorophyll a content in both sectors was low (2 - 55.8 mg m ?2) .
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