Paper No. 86-7
Presentation Time: 10:10 AM
USING ENVIRONMENTAL DNA TO INVESTIGATE HISTORICAL RECORD OF STORMS AND TSUNAMIS (Invited Presentation)
YAP, Wenshu1, SWITZER, Adam2, GOURAMANIS, Chris3, MAJEWSKI, Jedrzej1, HORTON, Benjamin P.4, MARZINELLI, Ezequiel5, DOMINEY-HOWES, Dale6, LABBATE, Maurizio7, WIJAYA, Winona8, YAN, Yu Ting1, JANKAEW, Kruawun9, SESHACHALAM, Srinivasalu10, BENAZIR, Benazir11, MEILIANDA, Ella12 and LAURO, Federico13, (1)Earth Observatory of Singapore, Nanyang Technological University, Singapore, 639798, Singapore, (2)Asian School of the Environment, Nanyang Technological University, 50 Nanyang Avenue,, Singapore, 639798, Singapore; Earth Observatory of Singapore, Nanyang Technological University, Singapore, 639798, Singapore, (3)Research School of Earth Sciences, Australian National University, Acton, ACT 0200, Australia, (4)Earth Observatory of Singapore, Nanyang Technological University, Singapore, 639798, Singapore; Asian School of the Environment, Nanyang Technological University, 50 Nanyang Avenue,, Singapore, 639798, Singapore, (5)School of Life and Environmental Sciences, The University of Sydney, Camperdown, NSW 2050, Australia, (6)School of Geosciences, The University of Sydney, Camperdown, NSW 2006, Australia, (7)University of Technology Sydney, Ultimo, NSW 2007, Australia, (8)Asian School of the Environment, Nanyang Technological University, 50 Nanyang Avenue,, Singapore, 639798, Singapore, (9)Faculty of Sciences, Chulalongkorn University, Pathum Wan, Bangkok 10330, Thailand, (10)Institute for Ocean Management, Anna University, Chennai, Tamil Nadu 600025, India, (11)Department of Civil and Environmental Engineering, Universitas Gadjah Mada, Sleman, Daerah Istimewa Yogyakarta 55281, Indonesia, (12)Civil Engineering Department, Syiah Kuala University, Darussalam, Aceh 23111, Indonesia, (13)Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore 639798, Singapore; Asian School of the Environment, Nanyang Technological University, 50 Nanyang Avenue,, Singapore, 639798, Singapore
Studying geological records of storms and tsunamis events is essential for understanding coastal long-term risk and vulnerability. However, distinguishing storm and tsunami deposits in the records is challenging due to their similar features, and the post-depositional deterioration of indicators. To address this, we explore using environmental DNA (eDNA) analysis in coastal hazard geological records. eDNA analysis allows simultaneous detection of multiple organisms using samples from the environment, such as sediment, soil, and water. Taking advantage of this innovation, we conducted a comprehensive investigation in three case studies from Asia.
First, we investigate eDNA approach’s ability to differentiate storm and tsunami overwash deposits. We collected sediment samples from Phra Thong Island, Thailand, and Cuddalore, India, where both locations were impacted by the 2004 Indian Ocean Tsunami followed by a storm. The multivariate analysis showed significant microbial community differences between overwash deposits and non-overwash soil and sediment (p-value < 0.0001).
Second, we examine the capability of the eDNA approach in characterizing tsunami deposits when there is limited grain size evidence. We collected sediment samples from Palu, Indonesia, impacted by the 2018 Palu-Donggala earthquake and tsunami. Our results showed significant microbial community differences between tsunami and pre-tsunami layers (p-value = 0.003).
Third, to address the preservation limitation of tsunami indicators, we extend our eDNA analysis to a sequence of palaeotsunami deposits in Phra Thong Island, Thailand. We found distinct microbial communities in the tsunami deposits compared to the overlying and underlying mud layers (p-value = 0.0269). However, these differences faded in sediment layers > 2,800 years.
In conclusion, our studies demonstrate the potential of eDNA analysis in advancing storm and tsunami reconstructions from geological records. By integrating eDNA as a proxy, we overcome some limitations associated with other indicators, allowing precise differentiation between storm and tsunami overwash deposits. Although challenges persist in distinguishing older overwash deposits, our work represents a significant step in documenting prehistorical coastal hazards and their impact on coastal communities throughout history.
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