31518
2010
2010
eng
article
1
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Human evolution in a variable environment : the amplifier lakes of Eastern Africa
The development of rise Cenozoic East African Rift System (EARS) profoundly re-shaped the landscape and significantly increased the amplitude of short-term environmental response to climate variation. In particular, the development of amplifier lakes in rift basins after three million years ago significantly contributed to this exceptional sensitivity of East Africa to climate change compared to elsewhere on the African continent. Amplifier lakes are characterized by tectonically-formed graben morphologies in combination with an extreme contrast between high precipitation in the elevated parts of the catchment and high evaporation in the lake area. Such amplifier lakes respond rapidly to moderate, precessional-forced climate shifts, and as they do so apply dramatic environmental pressure to the biosphere. Rift basins, when either extremely dry or lake-filled, form important barriers for migration, mixing and competition of different populations of animals and hominins. Amplifier lakes link long-term, high-amplitude tectonic processes and short-term environmental fluctuations. East Africa may have become the place where early humans evolved as a consequence of this strong link between different time scales. (C) 2010 Elsevier Ltd. All rights reserved.
http://www.sciencedirect.com/science/journal/02773791
10.1016/j.quascirev.2010.07.007
0277-3791
allegro:1991-2014
10107835
Quaternary science reviews. - ISSN 0277-3791. - 29 (2010), 23-24, S. 2981 - 2988
Martin H. Trauth
Mark A. Maslin
Alan L. Deino
Annett Junginger
Moses Lesoloyia
Eric O. Odada
Daniel O. Olago
Lydia A. Olaka
Manfred Strecker
Ralph Tiedemann
Institut für Biochemie und Biologie
Institut für Geowissenschaften
Referiert
36974
2011
2011
eng
353
367
15
3
45
article
Springer
Dordrecht
1
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Environmental variability in Lake Naivasha, Kenya, over the last two centuries
Lake Naivasha, Kenya, is one of a number of freshwater lakes in the East African Rift System. Since the beginning of the twentieth century, it has experienced greater anthropogenic influence as a result of increasingly intensive farming of coffee, tea, flowers, and other horticultural crops within its catchment. The water-level history of Lake Naivasha over the past 200 years was derived from a combination of instrumental records and sediment data. In this study, we analysed diatoms in a lake sediment core to infer past lacustrine conductivity and total phosphorus concentrations. We also measured total nitrogen and carbon concentrations in the sediments. Core chronology was established by (210)Pb dating and covered a similar to 186-year history of natural (climatic) and human-induced environmental changes. Three stratigraphic zones in the core were identified using diatom assemblages. There was a change from littoral/epiphytic diatoms such as Gomphonema gracile and Cymbella muelleri, which occurred during a prolonged dry period from ca. 1820 to 1896 AD, through a transition period, to the present planktonic Aulacoseira sp. that favors nutrient-rich waters. This marked change in the diatom assemblage was caused by climate change, and later a strong anthropogenic overprint on the lake system. Increases in sediment accumulation rates since 1928, from 0.01 to 0.08 g cm(-2) year(-1) correlate with an increase in diatom-inferred total phosphorus concentrations since the beginning of the twentieth century. The increase in phosphorus accumulation suggests increasing eutrophication of freshwater Lake Naivasha. This study identified two major periods in the lake's history: (1) the period from 1820 to 1950 AD, during which the lake was affected mainly by natural climate variations, and (2) the period since 1950, during which the effects of anthropogenic activity overprinted those of natural climate variation.
Journal of paleolimnolog
10.1007/s10933-011-9502-4
0921-2728
wos:2011-2013
WOS:000289850100004
Stoof-Leichsenring, KR (reprint author), Univ Potsdam, Unit Evolutionary Biol Systemat Zool, Inst Biochem & Biol, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany., stoof@uni-potsdam.de
German Research Foundation (DFG) [GRK 1364]; Government of Kenya
[MOST13/001/30C 59/10, 59/18, 59/22]; University of Nairobi
Kathleen Rosemarie Stoof-Leichsenring
Annett Junginger
Lydia A. Olaka
Ralph Tiedemann
Martin H. Trauth
eng
uncontrolled
Lake sediments
eng
uncontrolled
Diatoms
eng
uncontrolled
Conductivity
eng
uncontrolled
Lake Naivasha
eng
uncontrolled
Human impact
eng
uncontrolled
Eutrophication
Institut für Biochemie und Biologie
Referiert