Biomarker records in penguin droppings and observed changes in penguin communities and their response to the ENSO in the Western Antarctic

Lipid biomarkers in AD2 penguin droppings-amend soil core from the Ardley Island, Western Antarctic, were dated using ^210Pb. Changes in the fatty acid ratios of nC18： 2/nC18：0 from the penguin droppings reflect climate changes coincident with ENNO events during 1931-2006. The occurrence of the minimum values in the depth of 2-3 and 6-7 cm are consistent with the end of ENSO in 1958 and 1983, respectively, reflecting a lag of the biomarker records in AD2 penguin droppings-amend soil in climatic signatures. This study also reveals that the changes in the relative concentration of n-alkanes nC23, the ratios of nC23/nC17 and ∑nC21-/∑nC22^＋, and carbon preferential index （CPI） values collectively indicate the variations of soil microor- ganism and lower plant, which are closely related to climate changes. The ratios of bacterial fatty acids iC15：0/aC15：0 reflect the increasing significance of microorganism.activities during the two periods that occurred at the end years of ENSO. Decrease in CPIA value and increase in ∑nC21^-/∑nC22^＋ indicate that low molecular weight fatty acids are derived from microorganism; and their insignificant correlation with Pr/Ph suggests microorganisms play an important role in the relatively simply ecosystem in the Antarctic and are closely linked to climatic conditions. In addition, the observed penguin community indicates the popula- tion of penguin can largely reflect the impacts of global climate changes on the ecosystem.