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

Kawecka B.

Oceanological and Hydrobiological Studies

2003

Vol. 32, No. 1

27-38

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 (Rostafiński) Hansgirg prevailing), and green alga Klebsormidium rivulare (Kütz.) 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) .

Effect of different light conditions on cyanobactria and algal communities in Tatra Mts stream (Poland)

Kawecka B.

Oceanological and Hydrobiological Studies

2003

Vol. 32, No. 2

3-13

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 Kütz. 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 obtain the highest values in summer - autumn and the lowest in the winter - spring seasons.