Fine-interval (∼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 14C yr. Four distinct climatic phases bounded by sudden transitions are inferred: (1) variably dry ∼11,400-10,000 yr B.P., (2) humid ∼10,000-7200 yr B.P., (3) more seasonal ∼7200-2200 yr B.P., and (4) more arid ∼2200-0 yr B.P., with a dry "Little Ice Age" event ∼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 ∼2360-2550, ∼1400, ∼1030-1130, and ∼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.
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