The diatom record of V95-2P, a 7.6 m long sediment core collected from 67 m depth, is the first from the east central portion of Lake Victoria. A soil horizon developed at the coring site shortly before 12,400 14C yr BP due to a lakewide desiccation event. The radiocarbon chronology of the older half of this core is problematic, but if our estimated chronology is correct, then aridity and evaporative concentration of the lake are indicated by the presence of Thalassiosira rudolfi from > 12,400 BP to about 10,000 BP. Abundant Aulacoseira and generally rising biogenic silica concentrations may reflect enhanced water column mixing and rising precipitation:evaporation ratios ca. 10,000-8400 BP. A lakewide reorganization of diatom assemblages occurred around 7200 BP, when Aulacoseira nyassensis largely replaced A. granulata and after which rainfall and wind-driven mixing became more seasonally restricted. Pronounced reductions in offshore diatom deposition, from about 8300-5800 BP and after 3500 BP, may have been related to declines in the duration and/or intensity of wind-driven mixing. Increased aridity, and possibly deforestation in the lake basin, is indicated after 1400 BP.
Bibliographical noteFunding Information:
This paper is publication number 77 of IDEAL (International Decade for the East African Lakes), and was made possible by support from the National Science Foundation. Special thanks go to B. Buhya, K. Beuning, E. Ito, K. Kelts, D. Livingstone, P. Mayewski, G. Ngobi, R. McEwan and J. Swenson. We also acknowledge the assistance of the captain and crew of R/V Ibis (Ugandan Fisheries Research Institute), and the IDEAL coring team. Permission to conduct research on Lake Victoria was provided by the governments of Uganda and Tanzania.
Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.
- Biogenic silica
- Lake Victoria
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