30 May 2022
30 May 2022
Status: this preprint is currently under review for the journal CP.

1750 years of hydrological change in southern Australia: a bivalve oxygen isotope record from the Coorong Lagoon

Briony Kate Chamberlayne1, Jonathan James Tyler1, Deborah Haynes1,2, Yuexiao Shao1, John Tibby2, and Bronwyn May Gillanders3 Briony Kate Chamberlayne et al.
  • 1Department of Earth Sciences and Sprigg Geobiology Centre, The University of Adelaide, Adelaide, 5005, Australia
  • 2Department of Geography, Environment and Population, The University of Adelaide, Adelaide, 5005, Australia
  • 3Southern Seas Ecology Laboratories and the Environment Institute, School of Biological Sciences, The University of Adelaide, Adelaide, 5005, Australia

Abstract. Multi-centennial records of past hydroclimate change are essential to understanding the resilience of aquatic ecosystems to climatic events, in addition to guiding conservation and restoration efforts. Such data are also crucial for examining the long-term controls over regional hydroclimate, and the inherent variability in extreme droughts and floods. Here, we present a 1750-year record of hydroclimate variability in The Coorong South Lagoon, South Australia, part of an internationally significant wetland system at the mouth of Australia’s largest river, the Murray River. Oxygen isotope ratios were measured in Arthritica helmsi bivalve shells preserved in sediments. The oxygen isotope record shows periods of persistent low and high moisture balance from ~500–1050 years and ~1300–1800, respectively, which is consistent with other hydroclimate reconstructions from the region. The range of oxygen isotope values in the sedimentary shells do not differ significantly from the estimated range of modern specimens from the present day lagoon. These data suggest that the restricted and highly evaporated modern day conditions are not markedly different to the pre-impacted state over the last 1750 years, although the absence of A. helmsi in the contemporary lagoon is likely a response to increased salinity, nutrient loading, and anoxia during the last century. These insights are potentially useful both in guiding management efforts in the currently degraded South Lagoon, as well as for understanding long term water resource availability in the region.

Briony Kate Chamberlayne et al.

Status: open (until 27 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2022-39', Anonymous Referee #1, 04 Sep 2022 reply
    • RC2: 'Reply on RC1', Patrick De Deckker, 19 Sep 2022 reply
  • RC3: 'Comment on cp-2022-39', Anonymous Referee #3, 23 Sep 2022 reply

Briony Kate Chamberlayne et al.

Briony Kate Chamberlayne et al.


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Short summary
We used geochemical signals in shells preserved in sediments to create a 1750-year record of hydrological change in the Coorong Lagoon of South Australia. The record is interpreted to reflect the balance of evaporation and precipitation and shows that it has always been a highly evaporated system. The record also shows similarities to other environmental reconstructions from the region. This knowledge can increase our understanding of the potential impacts of environmental change.