Cyanobacteria and cyanobacterial toxins in the alkaline crater lakes Sonachi and Simbi, Kenya

Abstract

The phytoplankton communities and the production of cyanobacterial toxins were investigated in two alkaline Kenyan crater lakes, Lake Sonachi and Lake Simbi. Lake Sonachi was mainly dominated by the cyanobacterium Arthrospira fusiformis, Lake Simbi by A. fusiformis and Anabaenopsis abijatae. The phytoplankton biomasses measured were high, reaching up to 3159 mg l −1 in L. Sonachi and up to 348 mg l −1 in L. Simbi. Using HPLC techniques, one structural variant of the hepatotoxin microcystin (microcystin-RR) was found in L. Sonachi and four variants (microcystin-LR, -RR, -LA and -YR) were identified in L. Simbi. The neurotoxin anatoxin-a was found in both lakes. To our knowledge this is the first evidence of cyanobacterial toxins in L. Sonachi and L. Simbi. Total microcystin concentrations varied from 1.6 to 12.0 g microcystin-LR equivalents g −1 DW in L. Sonachi and from 19.7 to 39.0 g microcystin-LR equivalents g −1 DW in L. Simbi. Anatoxin-a concentrations ranged from 0.5 to 2.0 g g −1 DW in L. Sonachi and from 0 to 1.4 g g −1 DW in L. Simbi. In a monocyanobacterial strain of A. fusiformis, isolated from L. Sonachi, microcystin-YR and anatoxin-a were produced. The concentrations found were 2.2 g microcystin g −1 DW and 0.3 g anatoxin-a g −1 DW. This is the first study showing A. fusiformis as producer of microcystins and anatoxin-a. Since A. fusiformis occurs in mass developments in both lakes, a health risk for wildlife can be expected.

Tropical cyanobacterial blooms: a review of prevalence, problem taxa, toxins and influencing environmental factors

“…The frequent occurrence of cylindrospermopsin in Australia was expected given the higher frequency of recorded Cylindrospermopsis blooms (Griffiths and Saker, 2003). The second most encountered toxin in Africa was anatoxin, produced by blooms of Anabaenopsis, Arthrospira and Anabaena species (Ballot et al, 2005;Odokuma and Isirima, 2007). Despite the presence of Anabaena in tropical Asia, anatoxin was not detected, with the only two toxins detected being microcystin and cylindrospermopsin.…”

“…Blooms of Arthrospira fusiformis and Anabaenopsis abijitae that produced anatoxin-a were recorded in the Kenyan rift lakes (Ballot et al, 2005;Odokuma and Isirima, 2007) (Tab. 2; Fig.…”

A detailed time series assessment of the diet of Lesser Flamingos: further explanation for their itinerant behaviour

“…A toxic strain producing microcystin-YR and anatoxin-a was isolated from L. Sonachi, Kenya (Ballot et al, 2005). Microcystins (cyanobacterial hepatotoxins) and anatoxin-a (cyanobacterial neurotoxin) have been found to be present in cyanobacterial mats of the hot springs along the shores of L. Bogoria .…”

Toxin mixture in cyanobacterial blooms – a critical comparison of reality with current procedures employed in human health risk assessment

“…Spirulina fusiformis = platensis) was found to produce small amounts of both, microcystins and anatoxin-a (Ballot et al 2004;Ballot et al 2005). Positive ELISA-results were evidence for a possible contamination of Spirulina supplements with microcystins (Gilroy et al 2000).…”