People | Andy
Cohen
East African Paleoclimate and Ecosystem History
For the past 25 years my students and I have been interested in reconstructing
the history of East African climate and ecosystems over the entire
Quaternary, through the analysis of long sediment cores. Much of our
work has been conducted at Lake Tanganyika (photo A) where we have
looked at variability in complex ecosystems and the response of ecosystems
to lake level and climate change during the Holocene (e.g. Alin
and Cohen (2003); Alin and Cohen (2004)),
and have studied high resolution, varved records to understand linkages
between climate and lacustrine productivity (Cohen et al (2006)).
At Lake Malawi (photos B and C), my colleagues, students and I have
been engaged over the past few years in a very exciting effort, the Lake
Malawi Scientific Drilling Project. This drilling project
recovered almost 700m of core in 2005, the longest of which (382m)
provides a record of climate and environmental change for tropical
Africa over the past 1.5 million years (Cohen et al., 2000; Scholz
et al, 2006).
In 2006 I began a new study with colleague Jon Todd (Museum of Natural
History, London) investigating the paleolimnological history of Lake
Rukwa and its past hydrologic connections with Lake Tanganyika. This
work was spurred by our interest in the presence of endemic Tanganyikan
molluscs and crustaceans in the fossils of the Rukwa basin (photo D).
A. A storm
over the Mahale Mountains at Lake Tanganyika.
B. The
Lake
Malawi Scientific Drilling Project Viphya Barge with the SEACORE
drill
rig
mounted in port at Lake Malawi. Note the large blue dynamic
positioning
thruster
engines mounted on the two forward corners of the barge.
C. Retrieving the
hydraulic piston corer on the Viphya deck during
drilling at Lake Malawi.
D. With Hudson
Nkotagu and two Tanzanian game rangers at
Katavi National
Park.
We have just located
the point where paleolake Rukwa overspilled into the Lake
Tanganyika Basin
during the Early Holocene. Water on the left today flows to
Lake Tanganyika,
whereas water on the right flows to Lake Rukwa.
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