Payne R (2012) Volcanic impacts on peatland microbial communities: A tephropalaeoecological hypothesis-test,

NOTICE: this is the author's version of a work that was accepted for publication in Quaternary International resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in 12 13 ABSTRACT 14 15 Volcanic eruptions affect peatlands around the world, depositing volcanic ash (tephra) 16 and a variety of chemicals including compounds of sulphur. These volcanic impacts 17 may be important for many reasons, in particular sulphur deposition has been shown 18 to suppress peatland methane flux, potentially reinforcing climatic cooling. 19 Experiments have shown that sulphur deposition also forces changes in testate 20 amoeba communities, potentially relating to the reduced methane flux. Large volcanic 21 eruptions in regions with extensive peatlands are relatively rare so it is difficult to 22 assess the extent to which volcanic eruptions affect peatland microbial communities; 23 palaeoecological analyses across tephra layers provide a means to resolve this 24 uncertainty. In this study testate amoebae were analysed across multiple monoliths 25 from a peatland in southern Alaska containing two tephras, probably representing the 26 1883 eruption of Augustine Volcano and a 20 th Century eruption of Redoubt Volcano. 27 Results showed relatively distinct and often statistically significant changes in testate 28 amoeba community coincident with tephra layers which largely matched the response 29 found in experimental studies of sulphur deposition. The results suggest volcanic 30 impacts on peatland microbial communities which might relate to changes in methane 31 flux. 32 33 2