A calibration data set of 51 surface sediment samples from Lake Donggi Cona on the northeastern Tibetan Plateau was investigated to study the relationship between sub-fossil ostracod assemblages and water depth. Samples were collected over a depth range from 0.6 to 80 m. A total of 16 ostracod species was identified from the lake with bout half of the species restricted to the Tibetan Plateau and its adjacent mountain ranges and poorly known in terms of ecological preferences, and the other half displaying a mainly Holarctic distribution. Living macrophytes and macroalgae were recorded in Lake Donggi Cona down to a depth of about 30 m, and bivalve (Pisidium cf. zugmayeri) and gastropod (Gyraulus, Radix) shells were found down to depths of 43 and 48 m, respectively. The ostracod-water epth relationship was assessed by multivariate statistical analysis and ostracod-based transfer functions for water depth were constructed. Weighted averaging partial least squares (WA-PLS) regression provided the best model with a coefficient of determination r2 of 0.91 between measured and ostracod-inferred water depth, a root mean square error of prediction of 8% and a maximum bias of 10.6% of the gradient length, as assessed by leave ne-out cross-validation. Our results show the potential of ostracods as palaeo-depth indicators in appropriate settings. However, transfer-function applications using fossil ostracod assemblages for palaeo-depth estimations require a thorough understanding of the palaeolimnological conditions of lakes and therefore detailed multi-proxy analysis to avoid misinterpretation of ostracod-based inferences.
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Acknowledgments We like to thank Jianhui Chen, Yanyun Ji, Conrad Kopsch, Xiaolong Liu, Andreas Plank, Qili Yang and Sizhong Yang for help during fieldwork. Marjaana Lieb kindly performed the mollusk shell counting. Ian Boomer, Jonathan Holmes and an anonymous referee provided many constructive and thoughtful comments which helped to improve the manuscript. In addition, the journal editor Thomas J Whitmore made many helpful corrections and suggestion to improve the clarity of the manuscript. Part of the work reported here was conducted at the Limnological Research Center (LRC) of the University of Minnesota (USA) while S.M. was in receipt of a research fellowship of the German Research Foundation, and he would like to thank Emi Ito and other members of the LRC for their kind hospitality during his visit. In addition, S.M. is indebted to Emi Ito for critical comments concerning the application potentials of the presented transfer function. Amy Myrbo provided many editorial comments which helped to improve the manuscript. Funding for the work at Lake Donggi Cona was provided by the Alfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam, and the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG).
Copyright 2011 Elsevier B.V., All rights reserved.
- Surface-sediment samples
- Tibetan Plateau
- Water depth
- Weighted averaging partial least squares regression (WA-PLS)