Palaeohydrology of the southern Coorong Lagoon, inferred from oxygen isotope ratios of the bivalve Arthritica helmsi
Loading...
Date
2021-07-08
Journal Title
Journal ISSN
Volume Title
Publisher
Australasian Quaternary Association
Abstract
Understanding the resilience of aquatic ecosystems to climate and human impacts requires a long term perspective that is rarely attainable via standard monitoring programs. This is evident in the South Lagoon of the Coorong in South Australia where a history of ecosystem management has been based on limited knowledge of the range of natural variability. Here, we present a ~1750 year record of hydrological variability inferred from the oxygen isotope ratios of the bivalve Arthritica helmsi. Analysis of the controls of oxygen isotope fractionation in modern waters, and modern populations of A. helmsi inform the interpretation that the oxygen isotope ratios of shells preserved in the Coorong sediments reflect the precipitation/evaporation balance of lagoonal waters. Centennial scale variability in the oxygen isotope based hydroclimate record from the Coorong is consistent with other records in the region, contributing to a deeper understanding of the scale of natural hydrological variability in southeastern Australia during the last 2000 years. While the sedimentary bivalve data suggest that the lagoon was slightly less saline in pre-European times, the range of oxygen isotope variability within sedimentary bivalve shells is not statistically distinguishable from the range predicted by the hydrological conditions of the modern day Coorong South Lagoon, suggesting that present day hydrological conditions are not markedly unusual in the context of the past 1750 years. As a consequence, our bivalve oxygen isotope data suggest that major hydrological alterations to the Coorong South Lagoon – for example flushing the lagoon with sea water – could result in a departure from the natural hydrological state of the system over the last 2000 years.
Description
Keywords
Fresh water, Oxygen isotopes, Aquatic ecosystems, Climates, Human populations, Water, Sediments, Crustaceans
Citation
Chamberlayne, B. K., Tyler, J. J., Gillanders, B. M., Jacobsen, G. , Tibby, J., & Haynes, D. (2021). Palaeohydrology of the southern Coorong Lagoon, inferred from oxygen isotope ratios of the bivalve Arthritica helmsi. Paper presented to the Australasian Quaternary Association/Friends of the Pleistocene Pop-up Conference 2021, 8-9th July 2021. Retrieved from: http://aqua.org.au/wp-content/uploads/2021/07/Abstract-book-2021-1.pdf