Sedimentary Archives of Environmental Change and Human Impact in a Shallow Embayment

Abstract

This research uses a series of deep (1.5 - 5m) sediment cores collected from sub-tidal sediment of a shallow bay to explore connectivity within the catchment to coast continuum. Specifically, this thesis investigates; 1) the variation in sediment yield of a coastal catchment subject to widespread land-use changes, 2) Historical trends in metal pollution in a shallow bay and the relative impact of a high magnitude flood. 3) Relative changes in coastal primary production and algal community shifts following land use changes in the adjacent catchment, and 4) Long-term climatic features of the eastern Australian subtropics preserved in these fluvial marine sediments. Together, the research presented demonstrates value of these sedimentary archives in providing novel insights into the dynamics of the coastal zone. Coasts receive mineral and organic sediments transported from catchments through run-off. Mineral sediments provide important physical habitats for intertidal and marine organisms, while nutrients support high rates of productivity contributing to the ecological and functional diversity of coastal oceans. The modification of coastal catchments through human disturbance including; land clearing, impoundment construction, industrial, urban and agricultural activities have significantly altered the flux of this material from drainage basins to coastal environments. In many cases these changes have had negative impacts on valuable coastal ecosystems.