NH33A-1892
Application of paleoDNA for identification of paleotsunami deposits
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Witold Szczucinski1, Joanna Pawlowska2, Franck Lejzerowicz3, Yuichi Nishimura4, Mikolaj Kokocinski5, Wojciech Majewski6, Yugo Nakamura7 and Jan Pawlowski3, (1)Adam Mickiewicz University, Institute of Geology, Poznań, Poland, (2)Institute of Oceanology, Polish Academy of Sciences, Sopot, Poland, (3)Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland, (4)Institute of Seismology and Volcanology, Hokkaido University, Sapporo, Japan, (5)Department of Hydrobiology, Adam Mickiewicz University in Poznan, Poznan, Poland, (6)Institute of Paleobiology, Polish Academy of Sciences, Warszawa, Poland, (7)Muroto Geopark Promotion Committee, Muroto, Japan
Abstract:
The identification of sedimentary records of paleotsunamis is the key to tsunami hazard assessment. However, it is often challenging to distinguish the tsunami deposits due to their variability, influence of local context, variable sediment sources, as well as postdepositional alterations. Among the most commonly used approaches to identify paleotsunami is the study of microfossils (e.g. foraminifera, diatoms). They are most commonly used to show marine origin of sediments. The common problem with microfossils in coastal settings (eg. marshes, peat bogs) is that they may not be preserved. For instance, it was found during studies on post-depositional changes of 2004 tsunami deposits and in paleotsunami deposits in Thailand that the tests composed of calcium carbonate as well as from silica have been largely dissolved with time. The rapid progress in paleogenetic studies suggests that analyses of DNA preserved in marine sediments may be a new research direction. A recent successful application of the method to the deep sea and fjord sediments, greater than 30,000 years old proved that it is possible to extract DNA and identify it from sediments that are affected by oxygenated waters and bioturbating organisms. Here we apply the paleogenetic studies for a series of paleotsunami deposits from Urahoro, eastern Hokkaido Island, Japan dated to be from several hundreds of years to more than 2000 years old based on tephrochronology. The sandy tsunami deposits intercalated by muddy peat contained rare diatoms of various origin but foraminifera and radiolaria tests were missing. Nevertheless, we were able to retrieve short fragments of the foraminiferal DNA from marine species using high-throughput sequencing technology. Our study provides first evidence that eukaryotic DNA can be preserved in tsunami deposits in coastal marsh environment for as long as 2000 years even in absence of any micropaleontological evidence. Thus paleoDNA analyses may provide a new useful tool to help in identification of catastrophic coastal inundations.
