Preprints
https://doi.org/10.5194/cp-2022-39
https://doi.org/10.5194/cp-2022-39
30 May 2022
 | 30 May 2022
Status: a revised version of 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 Chamberlayne, Jonathan James Tyler, Deborah Haynes, Yuexiao Shao, John Tibby, and Bronwyn May Gillanders

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: final response (author comments only)

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
    • RC2: 'Reply on RC1', Patrick De Deckker, 19 Sep 2022
      • AC2: 'Reply on RC2', Briony Chamberlayne, 30 Nov 2022
    • AC1: 'Reply on RC1', Briony Chamberlayne, 30 Nov 2022
  • RC3: 'Comment on cp-2022-39', Anonymous Referee #3, 23 Sep 2022
    • AC3: 'Reply on RC3', Briony Chamberlayne, 01 Dec 2022

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.