Dinoflagellate-cyanobacterium communication may determine the composition of phytoplankton assemblage in a mesotrophic lake

Assaf Vardi, Daniella Schatz, Karen Beeri, Uzi Motro, Assaf Sukenik, Alex Levine, Aaron Kaplan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

163 Scopus citations


The reasons for annual variability in the composition of phytoplankton assemblages are poorly understood but may include competition for resources and allelopathic interactions [1-4]. We show that domination by the patch-forming dinoflagellate, Peridinium gatunense, or, alternatively, a bloom of a toxic cyanobacterium, Microcystis sp., in the Sea of Galilee [5] may be accounted for by mutual density-dependent allelopathic interactions. Over the last 11 years, the abundance of these species in the lake displayed strong negative correlation. Laboratory experiments showed reciprocal, density-dependent, but nutrient-independent, inhibition of growth. Application of spent P. gatunense medium induced sedimentation and, subsequently, massive lysis of Microcystis cells within 24 hr, and sedimentation and lysis were concomitant with a large rise in the level of McyB, which is involved in toxin biosynthesis by Microcystis [6]. P. gatunense responded to the presence of Microcystis by a species-specific pathway that involved a biphasic oxidative burst and activation of certain protein kinases. Blocking this recognition by MAP-kinase inhibitors abolished the biphasic oxidative burst and affected the fate (death or cell division) of the P. gatunense cells. We propose that patchy growth habits may confer enhanced defense capabilities, providing ecological advantages that compensate for the aggravated limitation of resources in the patch. Cross-talk via allelochemicals may explain the phytoplankton assemblage in the Sea of Galilee.

Original languageAmerican English
Pages (from-to)1767-1772
Number of pages6
JournalCurrent Biology
Issue number20
StatePublished - 15 Oct 2002

Bibliographical note

Funding Information:
We thank Drs. U. Pollingher and T. Zohary for the phytoplankton biomass data; Dr. M. Hisbergues, Dr. E. Dittmann, and Prof. T. Boerner for the antibody against McyB; and Prof. L. Reinhold for helpful discussions. The Israeli Science Foundation (ISF) and the Israeli Ministry of Science and Technology (MOST) supported this research.


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