Holocene environmental change on Kangaroo Island inferred from sedimentary ancient DNA in lake sediments

Miss Lucinda Duxbury^1,2,3, Dr Jonathan Tyler^1,3, Dr Linda Armbrecht², Dr Alexander Francke¹, Dr Haidee Cadd^4,8, Dr W. Boone Law^5,6, Atun Zawadzki⁷, Dr David Child⁷, Patricia Gadd⁷, Dr Geraldine Jacobsen⁷, Dr John Tibby⁵, Dr Kieren Mitchell^2,3

¹Department of Earth Sciences, The University Of Adelaide, North Terrace, Adelaide, Australia, ²Australian Centre for Ancient DNA, The University of Adelaide, North Terrace, Adelaide, Australia, ³ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH), The University of Adelaide, North Terrace, Adelaide, Australia, ⁴ARC Centre of Excellence for Australian Biodiversity and Heritage (CABAH), University of Wollongong, Wollongong, Australia, ⁵Department of Geography, Environment and Population, University of Adelaide, North Terrace, Adelaide, Australia, ⁶School of Biological Sciences, University of Adelaide, North Terrace, Adelaide, Australia, ⁷Australian Nuclear Science and Technology Organisation, Sydney, Australia, ⁸Chronos 14Carbon-Cycle Facility, Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia

Abstract:

Fire has long been an important part of Australian landscapes. However, anthropogenic climate change has heralded major shifts in fire regimes, negatively impacting ecosystems. These effects are expected to worsen in coming years, but there remain difficulties with projecting fire regime trajectories and their environmental impacts, in part due to a lack of data on centennial to millennial timescales. Uncertainties remain concerning the independent effects of climate and human impact on bushfires, and the long-term impacts of fire on both terrestrial and aquatic ecosystems.

This study aims to address these uncertainties by returning to Lashmars Lagoon, Kangaroo Island, a site of pioneering palaeoenvironmental research in South Australia that has been overlooked in recent decades. Kangaroo Island presents a fascinating case study, due to the putative abandonment of the island by ancient Aboriginal populations ~ 2,500 years ago.  As such, it represents a unique opportunity to study the impact of cessation of Aboriginal management practices on ecosystems prior to European invasion.

We collected a ~ 7 metre long sediment core from Lashmars Lagoon, which we dated to approximately 7,000 years before present. Our multiproxy approach combines traditional and novel analyses to reconstruct past aquatic and terrestrial ecosystems and the climatic, environmental and anthropogenic contexts in which they occurred. In this presentation, I will discuss our preliminary ecological reconstruction inferred from sedimentary ancient DNA extracted from 26 samples throughout the core and sequenced using shotgun metagenomics.

Biography:

Lucinda Duxbury is a postgraduate researcher at the University of Adelaide working on untangling the links between fire, environment, people and climate. She has a background in genetics, palaeontology, ecology and linguistics, and delights in interdisciplinary approaches to knowledge creation.