Carbon cycling within an East African lake revealed by the carbon isotope composition of diatom silica: a 25-ka record from Lake Challa, Mt. Kilimanjaro

Barker, Philip A.; Hurrell, Elizabeth R.; Leng, Melanie J.; Plessen, Birgit; Wolff, Christian; Conley, Daniel J.; Keppens, Eddy; Milne, I.; Cumming, Brian F.; Laird, Kathleen R.; Kendrick, Christopher P.; Wynn, P.; Verschuren, Dirk

doi:10.1016/j.quascirev.2012.07.016

Cited by 42 publications

(28 citation statements)

References 37 publications

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“…Kilimanjaro, including Lake Challa (Blaauw et al, 2010;Nelson et al, 2012;Barker et al, 2013) and Namelok wetland (Rucina et al, 2010). These studies provide evidence of late Holocene environmental change at a decadal to centennial scale and are being complemented by ongoing sedimentological (Githumbi et al, 2016) and multidisciplinary historical ecology studies (Courtney-Mustaphi et al, 2015).…”

Section: Paleoenvironmental Prospects In Semi-arid Amboselimentioning

confidence: 99%

Pollen, People and Place: Multidisciplinary Perspectives on Ecosystem Change at Amboseli, Kenya

et al. 2018

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This study presents a multidisciplinary perspective for understanding environmental change and emerging socio-ecological interactions across the Amboseli region of southwestern Kenya. We focus on late Holocene (<5,000 cal yr. BP) changes and continuities reconstructed from sedimentary, archeological, historical records and socio-ecological models. We utilize multi-disciplinary approaches to understand environmental-ecosystem-social interactions over the longue durée and use this to simulate different land use scenarios supporting conservation and sustainable livelihoods using a socio-ecological model. Today the semi-arid Amboseli landscape supports a large livestock and wildlife population, sustained by a wide variety of plants and extensive rangelands regulated by seasonal rainfall and human activity. Our data provide insight into how large-scale and long-term interactions of climate, people, livestock, wildlife and external connections have shaped the ecosystems across the Amboseli landscape. Environmental conditions were dry between ∼5,000 and 2,000 cal yr. BP, followed by two wet periods at ∼2,100-1,500 and 1,400-800 cal yr. BP with short dry periods; the most recent centuries were characterized by variable climate with alternative dry and wet phases with high spatial heterogeneity. Most evident in paleo and historical records is the changing woody to grass cover ratio, driven by changes in climate and fire regimes entwined with fluctuating elephant, cattle and wild ungulate populations moderated by human activity, including elephant ivory trade intensification. Archeological perspectives on the occupation of different groups (hunter-gatherers, pastoralists, and farmers) in Amboseli region and the relationships between them are discussed. An overview of the known history of humans and elephants, expanding networks of trade, and the arrival and integration of metallurgy, livestock and domesticated crops in the wider region is provided. In recent decades, increased runoff and flooding have resulted in the expansion of wetlands and a reduction of woody vegetation, compounding problems created by increased enclosure and privatization of these landscapes. However, most Githumbi et al.Long-Term Multidisciplinary Perspectives at Amboseli, Kenya of the wetlands outside of the protected area are drying up because of the intensified water extraction by the communities surrounding the National Park and on the adjacent mountains areas, who have increased in numbers, become sedentary and diversified land use around the wetlands.

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Section: Paleoenvironmental Prospects In Semi-arid Amboselimentioning

confidence: 99%

Pollen, People and Place: Multidisciplinary Perspectives on Ecosystem Change at Amboseli, Kenya

et al. 2018

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“…In marine sediments, this is usually primary productivity (e.g., Shemesh et al, 1995;Panizzo et al, 2014;Swann and Snelling, 2015) and/or changes in CO 2 (Heureux and Rickaby, 2015;Stoll et al, 2017). In the case of lake sediments, δ 13 C diatom is used to reconstruct changes in the balance between the source and amount of carbon supply and the productivity within the lake ecosystem (e.g., Barker et al, 2013).…”

Section: Carbonmentioning

confidence: 99%

A Review of the Stable Isotope Bio-geochemistry of the Global Silicon Cycle and Its Associated Trace Elements

et al. 2018

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“…This process inevitably causes some heating and injection of oxygen; consequently we assume that dissolved oxygen was 0.0 mg/l throughout the lower water column, as measured in situ between 45 and 50 m (Fig. 3B), and on several earlier occasions (e.g., Barker et al, 2013) with a different CTD instrument measuring in situ at greater depth. We also replace the ex situ deep-water temperature readings with those recorded on that date by the automatic temperature loggers (Figs.…”

Section: Water Columnmentioning

confidence: 99%

Sources of core and intact branched tetraether membrane lipids in the lacustrine environment: Anatomy of Lake Challa and its catchment, equatorial East Africa

Buckles

Weijers

Verschuren

et al. 2014

Geochimica et Cosmochimica Acta

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110

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The MBT/CBT palaeotemperature proxy uses the distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), membrane lipids that are supposed to derive from soil bacteria, to reconstruct mean annual air temperature (MAAT). Applied successfully in coastal marine sediments, its extension to lake-sediment records with potentially high time resolution would greatly expand its utility. Over the last years, however, studies have indicated the presence of additional sources of brGDGTs within lake systems. To constrain the factors influencing the MBT/CBT palaeotemperature proxy in lakes, detailed investigation of brGDGT fluxes in a modern lake system is necessary to identify their potential sources. This study concentrates on Lake Challa, a permanently stratified crater lake in equatorial East Africa with limited catchment area. An almost 3-year time series of approximately monthly samples of settling particles, supplemented with a depth profile of suspended particulate matter (SPM) and sets of profundal surface-sediment and catchment soil samples, were analysed for both the 'living' intact polar lipids (IPLs) and 'fossil' core lipids (CLs) of GDGTs. We found that brGDGTs are produced in oxic, suboxic and anoxic zones of the water column, and in substantial amounts compared to influxes from catchment soils. Additional in-situ production within the lake sediments is most probable, but cannot be definitely confirmed at this time. These lacustrine brGDGTs display a different response to temperature variation than soil-derived brGDGTs, signifying either a different physiological adaptation to changing conditions within the water column and/or a different composition of the respective bacterial communities. Using this specific relationship with temperature, a local calibration based on brGDGT distributions in SPM generates relatively accurate water temperature estimates from settling particles but fails for surface sediments.

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Carbon cycling within an East African lake revealed by the carbon isotope composition of diatom silica: a 25-ka record from Lake Challa, Mt. Kilimanjaro

Cited by 42 publications

References 37 publications

Pollen, People and Place: Multidisciplinary Perspectives on Ecosystem Change at Amboseli, Kenya

Pollen, People and Place: Multidisciplinary Perspectives on Ecosystem Change at Amboseli, Kenya

A Review of the Stable Isotope Bio-geochemistry of the Global Silicon Cycle and Its Associated Trace Elements

Sources of core and intact branched tetraether membrane lipids in the lacustrine environment: Anatomy of Lake Challa and its catchment, equatorial East Africa

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