Abstract:
Salinity in the climate sensitive tropical
endorheic crater lake Oloidien (Great African Rift
Valley, Kenya) decreased from hyposaline to subsaline
conditions during the period 2010–2015. The
change in salinity was accompanied by a pronounced
change in planktonic life forms—from blooms of the
cyanobacterium Arthrospira supporting tens of thousands
of Lesser Flamingos to highly diverse communities
of cyanobacteria and algae which do not sustain
the consumer birds. Besides the well-known macroand
microscopic lake life, a hidden diversity of
microorganisms was detected using molecular methods.
SSU rRNA gene clone libraries and data from
Ilumina Miseq sequencing of samples collected at the
two contrasting stages revealed distinct and highly
diverse microbial communities. Different bacterial
clades dominated the two samples. In 2011, Firmicutes
(class Bacilli) whose origin was the fecal waste
of birds were the dominant group. However, the
Cyanobacteria and Chloroflexi were the most prevalent
in 2015. From the microbial eukaryote samples
obtained in 2011, rotifers and ciliates that feed on
Arthrospira and rich bacterial food dominated the
plankton, while the cryptophytes were the most
prevalent in 2015. On the two occasions, a mixture
of organisms previously not known to occur in saline
or in freshwater habitats was found.
Description:
The authors thank the authorities of the
Republic of Kenya, especially the National Council for Science
and Technology for providing research permission (No. NCST/
RRI/12/1/BS/232). W.L. thanks for financial support of the State
High-Tech Research and Development Project (863) of the
Ministry of Science and Technology of China (2012AA021706,
2013AA065805), the National Natural Science Foundation of
China (No. 41376191) and State Key Laboratory of Microbial
Metabolism of Shanghai Jiao Tong University (MMLKF16-10).
