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The Scientific World Journal
Volume 2012 (2012), Article ID 504135, 14 pages
Research Article

Plankton Microorganisms Coinciding with Two Consecutive Mass Fish Kills in a Newly Reconstructed Lake

1Department of Ichthyology and Aquatic Environment, School of Agricultural Sciences, University of Thessaly, 384 46 Volos, Greece
2Department of Botany, School of Biology, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece
3Department of Biological Applications and Technology, University of Ioannina, 451 10 Ioannina, Greece

Received 6 October 2011; Accepted 4 December 2011

Academic Editors: B. A. P. da Gama, J. B. Gurtler, and G. Hobbs

Copyright © 2012 Andreas Oikonomou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Lake Karla, Greece, was dried up in 1962 and its refilling started in 2009. We examined the Cyanobacteria and unicellular eukaryotes found during two fish kill incidents, in March and April 2010, in order to detect possible causative agents. Both microscopic and molecular (16S/18S rRNA gene diversity) identification were applied. Potentially toxic Cyanobacteria included representatives of the Planktothrix and Anabaena groups. Known toxic eukaryotes or parasites related to fish kill events were Prymnesium parvum and Pfiesteria cf. piscicida, the latter being reported in an inland lake for the second time. Other potentially harmful microorganisms, for fish and other aquatic life, included representatives of Fungi, Mesomycetozoa, Alveolata, and Heterokontophyta (stramenopiles). In addition, Euglenophyta, Chlorophyta, and diatoms were represented by species indicative of hypertrophic conditions. The pioneers of L. Karla’s plankton during the first months of its water refilling process included species that could cause the two observed fish kill events.