Vulnerability of Nostoc muscorum Agardh (Cyanophyceae) motile hormogonia to ciliate grazing

Experiments were carried out to investigate if the stage of life cycle of Nostoc muscorum Agardh alters vulnerability to grazing by Pseudomicrothorax dubius Maupas. When the percentage of motile hormogonia of all counted trichomes exceeded 10%, most of the grazers (80%-100%) became satiated within 2...

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Bibliographic Details
Published in:Journal of phycology 2004-04, Vol.40 (2), p.271-274
Main Authors: Pajdak-Stos, A, Fialkowska, E, Fyda, J
Format: Article
Language:English
Subjects:
Ciliophora
Freshwater
Furgasonia blochmanni
Nassula tumida
Nostoc muscorum
Pseudomicrothorax dubius
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Summary:Experiments were carried out to investigate if the stage of life cycle of Nostoc muscorum Agardh alters vulnerability to grazing by Pseudomicrothorax dubius Maupas. When the percentage of motile hormogonia of all counted trichomes exceeded 10%, most of the grazers (80%-100%) became satiated within 2 h. In most cases (90%) grazers successfully attacked motile hormogonia. Attacks on nonmotile trichomes were much rarer (8%) and mainly unsuccessful. Direct observations revealed that hormogonia could be ingested by the ciliates as long as they remained motile. Hormogonia already adhered to the bottom were still recognized by ciliates as potential food but were not ingested. We did not observe attacks on old vegetative colonies. This is apparently the first report on the motile stage of Nostoc being susceptible to ciliate grazing. Experiments with other grazers, Nassula tumida Maskell and two different clones of Furgasonia blochmanni Faure-Fremiet, showed that only one clone of F. blochmanni was able to feed on motile hormogonia, whereas the second clone and N. tumida showed no interest in them.
ISSN:0022-3646
1529-8817
DOI:10.111/j.1529-8817.2004.03166.x