Oral Presentation Australian Society for Limnology Congress 2013

Sedimentary pigment analysis reveals pre-European shift in trophic state in a freshwater lake - evidence from Lake Colac, Western Victoria, Australia  (#87)

PHUONG DOAN 1 , Peter Gell 1 , Keely Mills 1 2
  1. Centre for Environmental Management, School of Science, Information Technology and Engineering, The University of Ballarat, Ballarat, Victoria 3353, Australia.
  2. Department of Geography, Loughborough University, Leics LE11 3TU, United Kingdom

Recent research has focused on freshwater ecosystems to observe their “coping mechanisms” and to ascertain whether the aquatic systems demonstrate an ability to recover post-drought, as well as other long-term responses. While much of this research is focused on contemporary systems and associated monitoring, a lack of long-term studies on drought in western Victoria limits our ability to assess the vulnerability of this region to climate change and variability. For future management it is becoming more important to understand how these systems have responded to periods of drought in the past: (1) whether they have undergone similar transformations and and (2) whether they have exhibited signs of recovery, thus implying the level of system resilience to future hydro-climatic change.
Paleolimnological approaches provide insight into how shallow lake systems in western Victoria have changed in response to past climate variation, and possibly previous droughts, at a millennial scale. Using a multi-proxy palaeoecological approach, the history of key western Victorian lake system was reconstructed. Evidence retrieved from the sediment record suggests that a long-term severe drought occurred prior to European settlement. This drought led to a trophic state switch in the functioning of the lake system, from a macrophyte to a phytoplankton dominated system, which has remained stable through the period leading up to the recent drought.