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Guano-derived δ13C-based paleo-hydroclimate record from Gaura cu Musca Cave, SW Romania

Onac, Bogdan P., Forray, Ferenc L., Wynn, Jonathan G., Giurgiu, Alexandra M.
Environmental earth sciences 2014 v.71 no.9 pp. 4061-4069
Chiroptera, Musca, animal manures, charcoal, clay, climate, color, peatlands, pollen, sediments, summer, vegetation, Romania
The δ¹³C values of 23 unevenly spaced guano samples from a 17-cm long clay sediment profile in Gaura cu Muscă Cave (GM), in SW Romania, made it possible to preliminarily characterize the Medieval Warm Period summer hydroclimate regime. The beginning of the sequence (AD 990) was rather wet for more than a century, before becoming progressively drier. After a brief, yet distinct wet period around AD 1170, drier conditions, with a possible shift from C₃to a mixed C₃-dominated/C₄type vegetation (2 ‰ lower δ¹³C values), prevailed for almost half a century before the climate became colder and wetter at the onset of the Little Ice Age, when bats left the cave. The guano-inferred wet and dry intervals from the GM Cave are mirrored by changes in the color and amount of clay accumulated in the cave. They also agree well with reconstructions based on pollen and charcoal from peat bogs and δ¹³C and δ¹⁸O on speleothems from other Romanian sites. Overall, these results indicate that the δ¹³C of bat guano can provide a sensitive record of the short-term coupling between local/regional climate and the plant–insect–bat–guano system.