Abstract
The transport of moisture in the tropics is a critical process for the global energy budget and on geologic timescales, has markedly influenced continental landscapes, migratory pathways, and biological evolution. Here we present a continuous, first-of-its-kind 1.3-My record of continental hydroclimate and lake-level variability derived from drill core data from Lake Malawi, East Africa (9–15° S). Over the Quaternary, we observe dramatic shifts in effective moisture, resulting in large-scale changes in one of the world’s largest lakes and most diverse freshwater ecosystems. Results show evidence for 24 lake level drops of more than 200 m during the Late Quaternary, including 15 lowstands when water levels were more than 400 m lower than modern. A dramatic shift is observed at the Mid-Pleistocene Transition (MPT), consistent with far-field climate forcing, which separates vastly different hydroclimate regimes before and after ∼800,000 years ago. Before 800 ka, lake levels were lower, indicating a climate drier than today, and water levels changed frequently. Following the MPT high-amplitude lake level variations dominate the record. From 800 to 100 ka, a deep, often overfilled lake occupied the basin, indicating a wetter climate, but these highstands were interrupted by prolonged intervals of extreme drought. Periods of high lake level are observed during times of high eccentricity. The extreme hydroclimate variability exerted a profound influence on the Lake Malawi endemic cichlid fish species flock; the geographically extensive habitat reconfiguration provided novel ecological opportunities, enabling new populations to differentiate rapidly to distinct species.
Document Type
Article
Publication Date
2015
Digital Object Identifier (DOI)
https://doi.org/10.1073/pnas.1512864112
Funding Information
We thank the government of Malawi for permission to conduct the research. The research was support by the National Science Foundation (NSF) Earth System History Program and NSF Grant EAR 0602453. Additional support for core collection was provided by the International Continental Scientific Drilling Program. Core archival support was provided by the LacCore Facility, the US National Lacustrine Core Repository at the University of Minnesota.
Repository Citation
Lyons, Robert P.; Scholz, Christopher; Cohen, Andrew S.; King, John W.; Brown, Erik T.; Ivory, Sarah J.; Johnson, Thomas C.; Deino, Alan L.; Reinthal, Peter N.; McGlue, Michael M.; and Blome, Margaret W., "Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity" (2015). Earth and Environmental Sciences Faculty Publications. 64.
https://uknowledge.uky.edu/ees_facpub/64
