A high-resolution 11,400-yr diatom record from Lake Victoria, East Africa

Fine-interval (similar to 30-45 yr) sampling of a core from Lake Victoria's Damba Channel shows that numerous abrupt changes in the lake's diatom assemblages have occurred in response to climatic fluctuations over the past 11,400 C-14 yr, Four distinct climatic phases bounded by sudden transitions are inferred: (1) variably dry similar to 11,400-10,000 yr B.P., (2) humid similar to 10,000-7200 yr B.P., (3) more seasonal similar to 7200-2200 yr B.P., and (4) more arid similar to 2200-0 yr B.P., with a dry ''Little Ice Age'' event similar to 600-200 yr B.P. The diatom-inferred paleoclimatic history for northern Lake Victoria closely resembles that inferred from a well-dated pollen record from Pilkington Bay, Spectral analysis of the diatom record reveals strong periodicities including globally distributed similar to 2360-2550, -1400, similar to 1030-1130, and similar to 500 cal-yr cycles. Repeated, rapid shifts between Aulacoseira- and Nitzschia-dominated diatom assemblages suggest that post-1960 changes in the lake's phytoplankton communities have had earlier, climate-driven analogs. (C) 1997 University of Washington.