Little Ice Age to modern lake-level fluctuations from Ferguson's Gulf, Lake Turkana, Kenya, based on sedimentology and ostracod assemblages

Abstract

AbstractLacustrine sedimentary records and the proxies contained within them are valuable archives of past climate. However, the resolution of these records is frequently coarse or contains a high degree of uncertainty, making it difficult to resolve how climatic variability impacts the ecosystems on which humans depend. The goal of this study is to couple recent sediment cores sampled at centimeter-scale resolution with paleo- and historical information about lake levels to document how changes in the paleoenvironment impact the paleoecology of a rift basin lake. We present multiproxy data from three short cores collected from Ferguson's Gulf (FG), a shallow embayment connected to the western shore of Lake Turkana, Kenya. Five distinct biozones were interpreted on the basis of ostracods and geochemistry (δ18O, δ13C, and major elements), spanning the Little Ice Age (LIA) to the modern. Overall, ostracod total abundance and assemblage diversity decreased up-core, with the largest total abundance and genera diversity occurring during the LIA. This fits with regional datasets that indicate the Eastern Branch of the East African Rift System was wetter during the LIA than it is today. This also suggests that human impact in and around Lake Turkana has weakened the resiliency of the ecosystems in FG.