The carbon isotopic ratios of organic matter in fish fossils from diatomites and other lake beds in the HSPDP drill core from Tugen Hills, Kenya (2.56–3.29 Ma) reflect trophic resource uses, and can indicate the dietary habitats of fish in the paleolake. This information offers insight into how fish communities responded to lake-level fluctuations during the Plio-Pleistocene in the East African Rift Valley. We have compared this record with fish fossil isotopes from both a previously published study of a Lake Malawi drill core (139 ka–present) and core top (modern ca 1978) samples collected at the water/sediment boundary from Lake Turkana (Kenya) of known environmental provenance. Both the Lake Malawi drill core fossils (−7.2‰ to −27.5‰ VPDB) and modern Lake Turkana samples (−16‰ to −24.6‰ VPDB) have δ13C values indicating a mix of near-shore and deep-water pelagic species. In contrast, the δ13C values for the Tugen Hills core fossils vary only between −20‰ and −27‰ VPDB. The absence of δ13C values greater than −19‰, suggests none of these fossils are derived from near-shore benthic habitats. The lack of shallow water, benthic lacustrine fish fossils through the Tugen Hills lake cycles may indicate that the rate of change from low-lake stands to deeper lake phases was very rapid, and shallow water communities were not established for long enough to leave a fish fossil record at the core site. These results strongly suggest that lake level responses to climate variability in the Baringo basin of the East African Rift were very abrupt during the Plio-Pleistocene transition.
Bibliographical noteFunding Information:
The National Science Foundation ( EAR1123000 , EAR1338553 , BCS124185 ) and the International Continental Drilling Program provided support for this research. MSCL core logging was done at the National Lakes Core Repository (LacCore). We thank LacCore, Kristina Brady, Jessamy Doman, Sarah Ivory, Beau Marshall, Dennis Njagi, Anders Noren, Ryan O'Grady, Steve Rucina, Rich Szenmiklosi, Gladys Tuitoek, Chad Yost, Jacob Marker, and Julia Richter for their assistance with this work. This is publication 20 of the Hominin Sites and Paleolakes Drilling Project (HSPDP).
© 2019 Elsevier B.V.
Copyright 2020 Elsevier B.V., All rights reserved.
- East African lakes
- Fish habitats
- Fish paleoecology
- Isotopic geochemistry
- Plio-Pleistocene climate
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