Publication Date:
2021-05-19
Description:
For decades frequent mass mortalities of Lesser Flamingos (Phoeniconaias minor Geoffroy)
have been observed at alkaline-saline Kenyan Rift Valley lakes. To estimate the potential
influence of toxic cyanobacteria on these mass deaths, the phytoplankton communities were
investigated in Lakes Bogoria, Nakuru, and Elmenteita. Cyanobacterial toxins were analyzed
both in the phytoplankton from the three lakes and in isolated monocyanobacterial strains of
Arthrospira fusiformis, Anabaenopsis abijatae, Spirulina subsalsa and Phormidium
terebriformis. Lake Bogoria was dominated by the cyanobacterium A. fusiformis. In L.
Nakuru and L. Elmenteita the phytoplankton mainly consisted of A. fusiformis, Anabaenopsis
abijatae and A. arnoldii, and in L. Nakuru an unknown Anabaena sp. was also found.
Furthermore, this is the first time A. abijatae and the unknown Anabaena sp. have been found
in Kenyan lakes. Phytoplankton wet weight biomass was found to be high, reaching 777 mg
L-1 in L. Bogoria, 104 mg L-1 in L. Nakuru and 202 mg L-1 in L. Elmenteita. Using HPLC, the
cyanobacterial hepatotoxins microcystin-LR, -RR -YR, -LF and -LA and the neurotoxin
anatoxin-a were detected in phytoplankton samples from L. Bogoria and L. Nakuru. Total
microcystin concentrations amounted to 155 μg microcystin-LR equivalents g-1 DW in L.
Bogoria, and 4593 μg microcystin-LR equivalents g-1 DW in L. Nakuru, with anatoxin-a
concentrations at 9 μg g-1 DW in L. Bogoria and 223 μg g-1 DW in L. Nakuru. In L.
Elmenteita phytoplankton, no cyanobacterial toxins were found. A. fusiformis was identified
as one source of the toxins. The isolated strain of A. fusiformis from L Bogoria was found to
produce both microcystin-YR (15.0 μg g-1 DW) and anatoxin-a (10.4 μg g-1 DW), whilst the
A. fusiformis strain from L. Nakuru was found to produce anatoxin-a (0.14 μg g-1 DW). Since
A. fusiformis mass developments are characteristic of alkaline-saline lakes, health risks to
wildlife, especially the Arthrospira-consuming Lesser Flamingo, may be expected.
Description:
Published
Keywords:
Bacteria
;
Phytoplankton
;
Biological poisons
;
Toxicology
;
Alkalinity
;
Chemical properties
;
Freshwater lakes
Repository Name:
AquaDocs
Type:
Report Section
,
Not Known
Format:
pp.83-105
Permalink
