Original paper

Occurrence and toxicity of cyanobacterial blooms dominated by Anabaena lemmermannii P. Richter and Aphanizomenon spp. in boreal lakes in 2003

Lepistö, Liisa; Rapala, Jarkko; Lyra, Christina; Berg, Katri A.; Erkomaa, Kirsti; Issakainen, Johanna

Abstract

Anabaena lemmermannii P. Richter is one of the dominant species in cyanobacterial mass occurrences in boreal lakes, even in relatively oligotrophic ones. Adverse health effects reported by swimmers were possibly caused by A. lemmermannii, since the species is capable of producing hepatotoxins (microcystins) and different types of neurotoxins (anatoxin-a, anatoxin-a(S) and putatively PSP-toxins). The phylogenetic position of A. lemmermannii is not clear since the morphotypes of Anabaena and Aphanizomenon have been intermixed in phylogenetic studies. Aphanizomenon species are also capable of producing neurotoxins. In the summer 2003, a total of 106 cyanobacterial bloom samples were analysed microscopically and for the toxins. In this study, 32 cyanobacterial blooms dominated or co-dominated by A. lemmermannii and 15 blooms by Aphanizomenon spp. were treated in order to compare the toxin concentrations of the different bloom types in boreal lakes. Seven reports of adverse health effects by swimmers were connected to the blooms, six of them to A. lemmermannii blooms from oligotrophic or mesotrophic lakes, and one to an Aphanizomenon bloom from a eutrophic lake. However, due to the relatively low number of the adverse health reports, no clear connection could be made to toxin concentrations observed. Microcystins, anatoxin-a, PSP-toxins and putatively anatoxin-a(S) were detected in the A. lemmermannii blooms, occasionally in high concentrations, while only microcystins and low anatoxin-a concentrations were detected in the Aphanizomenon blooms. Microcystin-containing blooms were detected in humic, eutrophic lakes with low total N to total P ratio. Higher microcystin concentrations were detected in the blooms during the late blooming period. Blooms that contained anatoxin-a were detected in oligo-humic, oligotrophic and mesotrophic lakes with high total N to total P ratio. The field data presented in this study suggests that Anabaena lemmermannii blooms were generally more toxic than Aphanizomenon spp. blooms, that neurotoxic blooms were mainly connected to A. lemmermannii, and that hepatotoxic and neurotoxic blooms occurred in different lake types.

Keywords

anabaena lemmermanniiaphanizomenon sppcyanobacterial bloomsmicrocystinanatoxin-aanatoxin-a(s)psp-toxins