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Contrasting microcystin production and cyanobacterial population dynamics in two Planktothrix dominated freshwater lakes

Janse, I. and Kardinaal, W.E.A. and Kamst-van Agterveld, M.P. and Meima, M. and Visser, P.M. and Zwart, G. (2005) Contrasting microcystin production and cyanobacterial population dynamics in two Planktothrix dominated freshwater lakes. Environmental Microbiology, 7, 1514-1524. ISSN 1462-2912.

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Official URL: http://dx.doi.org/10.1111/j.1462-2920.2005.00858.x

Abstract

Microcystin concentrations in two Dutch lakes with an important Planktothrix component were related to the dynamics of cyanobacterial genotypes and biovolumes. Genotype composition was analysed by using denaturing gradient gel electrophoresis (DGGE) profiling of the intergenic transcribed spacer region of the rrn operon (rRNA-ITS), and biovolumes were measured by using microscopy. In Lake Tjeukemeer, microcystins were present throughout summer (maximum concentration 30 µg l1) while cyanobacterial diversity was low and very constant. The dominant phototroph was Planktothrix agardhii. In contrast, Lake Klinckenberg showed a high microcystin peak (up to 140 µg l1) of short duration. In this lake, cyanobacterial diversity was higher and very dynamic with apparent genotype successions. Several genotypes derived from DGGE field profiles matched with genotypes from cultures isolated from field samples. The microcystin peak measured in Lake Klinckenberg could be confidently linked to a bloom of Planktothrix rubescens, as microscopic and genotypic analysis showed identity of bloom samples and a toxin-producing P. rubescens culture. Toxin-producing genotypes were detected in the microbial community before they reached densities at which they were detected by using microscopy. Cyanobacterial biovolumes provided additional insights in bloom dynamics. In both lakes, the microcystin content per cell was highest at the onset of the blooms. Our results suggest that while genotypic characterization of a lake can be valuable for detection of toxic organisms, for some lakes a monitoring of algal biomass has sufficient predictive value for an assessment of toxin production.

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:11731
Deposited On:23 Nov 2011 01:00
Last Modified:31 Mar 2014 10:41

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