HOLOCENE

Abstract: Wetland degradation in the Upper Sooth East of South Australia is anl urgent management concem. Scant recent environmental data is available for the region and long-term monitoring data is lacking. Usually a palaeoecological analysis is able to reveal environmental change in the mediumii- to lonig-term past. However, the region is not conducive to palaeoecological investigation due to a fluctuatinig upper grouLndwater aquLifer and alkaline soils whiclh have destroyed most microfossils. It was found that the diatom assemlblage was preserved in the wetlanids of the region for the period of European settlemenit. Analysis of the diatom assemblage enabled production of an inferred salinity cuirve. In combination with a small amount of historical information that was available, the salinity trend for the wetlands, for the period of European agricultural activities, was identified. It was found that, while groundwater salinity has been inicreasinig, the wetland areas have experienced a freshening of surface xvater. This is due to an increase of throughflow of surface water, a result of constructed drainage systems flushing salts from the wetlands. Despite the freshening of wetlands they continue to degrade due to the changed hydrology, an impact of the drainage structures