ORIGINAL PAPER Reflectance spectroscopy: a new approach for reconstructing penguin population size from Antarctic ornithogenic sediments Xiaodong Liu • Jing Sun • Liguang Sun • Wenqi Liu • Yuhong Wang Received: 21 March 2008 / Accepted: 21 December 2010 / Published online: 14 January 2011 Ó Springer Science+Business Media B.V. 2011 Abstract Reflectance spectroscopy has several advantages compared to traditional chemical methods in paleolimnology. It requires little cost, involves minimal or no sample preparation and is rapid. There has, however, been limited use of reflectance spectros- copy in polar paleolimnological studies. This paper explores the application of reflectance spectroscopy to reconstruct historical changes in penguin population size in the maritime Antarctic. Two ornithogenic sediment cores on Ardley Island, Antarctica were analyzed. Penguin droppings and weathered soils were analyzed as reference materials. Principal component analysis and linear mixing modeling were performed on the spectral data to estimate the proportion of penguin guano in the sediments and these values were used to infer historical penguin population numbers. Historical penguin population size versus time, recon- structed from reflectance spectra, and population numbers inferred from previous geochemical analysis of bio-elements, were quite similar. Our results illus- trate the feasibility of rapidly inferring historical changes in penguin population size using reflectance spectroscopy on Antarctic ornithogenic sediments. Our findings suggest that this technique has potential for reconstructing past population numbers of other seabirds and mammals using lake sediments influenced by animal excrement. Keywords Reflectance spectroscopy Á Ornithogenic sediments Á Historical penguin populations Á Antarctica Introduction Antarctic lakes have long been considered simple ecosystems compared to lakes on other continents. Sedimentological and geochemical studies of lake sediments in the Antarctic region are therefore exceptionally helpful for reconstructing paleoclimate and paleoecology (Hodgson et al. 2004; Liu et al. 2007). Many geochemical proxies in sediments have been used to extract paleoenvironmental information (Birks and Birks 2006). In general, traditional meth- ods of geochemical analyses are time-consuming and relatively expensive (Foley et al. 1998). Reflectance spectroscopy, however, is a non-destructive technique X. Liu (&) Á L. Sun Institute of Polar Environment, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China e-mail: ycx@ustc.edu.cn J. Sun Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA W. Liu Instruments’ Center for Physical Science, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China Y. Wang National Institutes of Health, Bethesda, MD 20892, USA 123 J Paleolimnol (2011) 45:213–222 DOI 10.1007/s10933-010-9493-6