The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twenty-four-month research fellowship by Dr. Lindsay A. Powers to work with Dr. Peter Mwanza at Mzuzu University in Mzuzu, Malawi.
Describing the timing and variability of past temperature change on the continents is essential to understanding the behavior of the climate system, particularly regarding the "heat engine" of the tropics. The study of paleoclimates of continental systems has suffered from the lack of an independent paleotemperature tool capable of producing high-resolution temperature records. My dissertation research focused on the development of the TEX86 paleothermometer for use in lakes to reconstruct continental paleotemperatures. TEX86 can provide high-resolution lake surface temperature estimates from lake sediments that are independent of hydrologic or biologic interference. The TEX86 paleothermometer is based on the relative abundance of cyclopentane containing membrane lipids (GDGTs) produced by aquatic archaea known as Crenarchaeota. However, very little is known about these aquatic Crenarchaeota. This collaborative effort will involve characterizing the phylogenetic diversity of aquatic Crenarchaeota within Lake Malawi and describing their spatial and temporal distribution within the water column, in order to describe the ecology of these organisms and their relationship to in-situ temperature. Lake Malawi, a large and deep tropical lake, is ideally situated at the convergence of the eastern boundary of the African monsoon, and the southern extent of the Intertropical Convergence Zone, and is therefore a sensitive recorder of climate change. These conditions make Lake Malawi an ideal setting for high-resolution studies of climate dynamics in the tropics. Monthly water samples will be collected at several depths for GDGT and phylogenetic analysis to determine the spatial and temporal distribution of Crenarchaeota within the water column. Temperature, specific conductance, depth and dissolved oxygen will be measured concurrently with sampling. Water samples will be collected for nutrient analyses. The results of this work will provide essential information regarding the nature of the TEX86 temperature signal, specifically what temperature (seasonal versus annual, surface versus metalimnetic) is reflected by the proxy. Nutrient analyses will provide insight into the ecology of Crenarchaeota. Elucidating the phylogenetic structure of the Crenarchaeotal community in Lake Malawi will be a first step in describing the diversity of these organisms within a tropical lake. Increasing our understanding of the diversity and ecology of the aquatic Crenarchaeota will strengthen the TEX86 proxy resulting in a robust continental paleotemperature tool capable of producing high-resolution paleotemperature reconstructions.
