The catchment of the Yarra River has been subject to more than 160 years of non-indigenous occupation and is now inhabited by over three million people. Whilst much of the upland region of the Yarra River has a pristine catchment, the middle and lower sections of the river have been subject to intensive land use. Studies of the physicochemical status and ecological health of the middle and lower reaches of the Yarra indicate that the river generally has poor water quality. The floodplain of the Yarra River has been substantially modified by flood levee and drainage system construction along with other urban developments.
A combination of modern ecological monitoring, sediment geochemistry and palaeoecological investigation is being used to establish pre- and post-European contact conditions for the Yarra River floodplain. This poster focuses on the results gained from fossil diatom assemblages in sediments from Bolin Bolin Billabong.
The fossil record shows that the post-contact ecology of the billabong has not been stable, but rather has altered through different states, presumably reflecting changing historical land-use. Results indicate that substantial changes in sediment attributes, trophic state, vegetation (see Kershaw, Kershaw and Reid, this volume) and acidity have occurred in the billabong as a consequence of post-contact land-use. This poster concludes that the major changes to Bolin Bolin Billabong have been related to differential sediment delivery, associated with varying historical impacts on the Yarra.