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| Titel |
Present and past microbial life in continental salt pan sediments in Southern Africa |
| VerfasserIn |
Steffi Genderjahn, Kai Mangelsdorf, Mashal Alawi, Jens Kallmeyer, Dirk Wagner |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110314
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| Publikation (Nr.) |
 EGU/EGU2015-10298.pdf |
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| Zusammenfassung |
| The southwestern African region is characterized by strong climate variability. To get a better
understanding on the climate evolution and environmental condition in Namibia and South
Africa, terrestrial climate archives are investigated. Since there are almost no lakes,
continental salt pans represent the only terrestrial geoarchives with the potential to
preserve climate signals during sediment deposition. Climate has a strong impact on
the salt pan ecosystem, causing adaptation of salt pan microorganisms to varying
temperature, precipitation and salinity conditions. To reconstruct climate variability during
the Holocene, the composition, diversity and abundance of indigenous microbial
communities with depth and related to different soil parameters are investigated. We are
using a combined approach of microbiological and lipid biomarker analyses to
demonstrate the response of the microbial communities due to environmental changes. For
microbiological analyses outcrops were conducted or short cores (0-100 cm) were drilled at
four different salt pans in Aminuis, Koes and Witpan region having rather different
geochemical properties. The current work focused on changes within the microbial
communities due to the impact of long-term climate variation and the associated
environmental changes and is part of the project “Signals of climate and landscape
change preserved in southern African GeoArchives” in the scope of the SPACES
program, which is funded by the German Federal Ministry of Education and Research
(BMBF).
For a quantitative characterization of microbial communities molecular techniques such
as polymerase chain reaction (PCR) and real-time quantitative PCR (qPCR) based on the 16S
rRNA genes are used. Moreover, 454 sequencing technique is utilized to describe the
diversity and abundance of microorganisms in detail. Soil parameters are described by
standard soil scientific methods. Furthermore, microbial lipid biomarker analyses were done
to characterize living and past microbial biomass in relation to climate change. The
distribution of bacteria and archaea in salt pan sediments is strongly correlated to the
abundance of total organic carbon (TOC), which varied between 0.2 and 1.5%. Gene
copy numbers of bacteria and archaea decrease with depth. In the upper 10 cm of
the different salt pan sediments 104 to 106copies g-1 soil are quantified, while
gene copy numbers decrease with depth down to 103 copies g-1 soil. In general,
gene copy numbers of bacteria are higher than those of archaea and they show a
similar pattern in different salt pan sediments. TOC values increase due to higher
terrestrial input and the increase coincides with a shift within the microbial community. |
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