41. Reconstructing Past Estuarine Conditions

Organised by John Gibson, University of Tasmania. First meeting held 30 June - 1 July 2008 at Macquarie U.

PARTICIPANTS INCLUDE John Gibson, palaeoecologist and estuarine ecologist, U Tasmania (Leader) James Cloern, US Geological Survey Jeremy Austin, ancient DNA, University of Adelaide Christine Crawford, estuarine ecologist, U Tasmania Melanie Bishop, benthic marine ecologist, U Technology Sydney Peter Gell, palaeoecologist, Adelaide U Ralf Haese, GeoScience Australia Hank Heinjis, Environmental Radioactivity, Quaternary Dating Techniques, ANSTO Sydney Evelyn Krull, geochemistry, organic matter chemistry, CSIRO Land and Water SA Joanne Oakes, sediment biochemist, Southern Cross U Jeff Ross, benthic ecologist, U Tasmania Krystyna Saunders, U Tasmania Peter Scanes, Dept Environment and Climate Change NSW Kathryn Taffs, palaeoecologist, Southern Cross U John Tibby, palaeoecologist, Adelaide U Mark Warne, palaeoecologist, Deakin U

Jun 08 >

BACKGROUND

Many Australian estuaries are degraded due to eutrophication, discharge and accumulation of toxicants, geomorphologic interventions and within-estuary recreation and industry. Often an aim is stated of returning estuaries to conditions similar to those experienced prior to European settlement. The question then is: what were the conditions like prior to 1778? One approach is through sediments deposited prior to European settlement.

In Australia the short period of European habitation means that pre-settlement sediment can be accessed relatively easily through collection of sediment cores. Sedimentological, chemical and biological characteristics of the cores can be measured and the conditions under which the sediment was formed deduced.

As the relationship between proxy and condition is often indirect (e.g., diatom species composition in cores is often used to reconstruct past nutrient concentrations), sediment records need the relationship between proxy and condition to be critically assessed and fully understood. This is a particular problem for estuaries due to the inherent variability of these systems resulting from the changing balance of tidal and riverine inputs overlain on seasonal (e.g., bar opening and closing) and longer-term cycles.

Working group meeting

The Working Group participants came from a wide variety of backgrounds, ranging from estuarine management to experts in modern estuarine processes to palaeoecologists. A number of cautionary tales of estuarine (mis-)management were presented and there was discussion around the topic of what indices should be monitored to determine estuarine health and how palaeoenvironmental data could be included in managing estuarine systems.

Three main outputs were proposed:

(i) Preparation of a research grant that will fund the development of a 'toolbox' that will educate managers in the possible role of palaeoestuarine research into estuarine management.

(ii) A review paper for 'Estuaries and Coasts' that will highlight the application of palaeoestuarine studies to estuary management.

(iii) A book in the Developments in Palaeoenvironmental Research Series (see http://post.queensu.ca/~smolj/dper/index.html) that will review in depth palaeoestuarine research from both purely scientific and management points of view.

This Working Group is likely to evolve as these outputs develop.

Last updated July 2008