Poster Presentation Australian Society for Limnology Congress 2013

Hydrological connectivity and ecological functional processes in inland floodplain wetlands: nutrient and carbon cycling (#210)

Tsuyoshi Kobayashi 1 , Skye Wassens 2 , Timothy J Ralph 3 , Darren S Ryder 4 , Neil Saintilan 1 , Debashish Mazumder 5 , Li Wen 1 , Simon J Hunter 1
  1. Office of Environment and Heritage NSW, Department of Premier and Cabinet, PO Box A290 Sydney South, NSW 1232, Australia
  2. School of Environmental Sciences, Charles Sturt University, PO Box 789 Albury, NSW 2640, Australia
  3. Depatment of Environment and Geography, Macquarie University, Sydney, NSW 2109, Australia
  4. Ecosystem Management, University of New England, Armidale, NSW 2351, Australia
  5. Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia

Floodplain wetlands have intricate multi-channeled networks and unpredictable wet and dry phases related to variable hydrological regimes and geomorphic processes such as sedimentation and erosion. Hydrological reconnection of river channels with outer floodplain and wetland habitats initiates mobilisation and transformation of nutrients and carbon in inland floodplain wetlands. In this study, we aim to show habitat-dependent patterns of mobilisation and transformation of nutrients (total and dissolved nitrogen and phosphorus) and dissolved organic carbon (DOC) following environmental water releases, based on the available data from the Murrumbidgee Wetlands, Macquarie Marshes and Gwydir Wetlands. In general, concentrations of nutrients and DOC are lower within channels and higher on the floodplain and in wetlands where shallow inundation and mixing of topsoil with water occurs. Higher concentrations of nutrients and DOC on the floodplain represent a combination of supply from channels coupled with in situ releases from the water-soil interface. The volume, timing, depth, rate of rise and fall, and spatial distribution of water being introduced to floodplain wetlands influence the amount and distribution of nutrients and carbon in these systems. Rates of ecological functional processes such as primary productivity and respiration (or decomposition) are closely related to concentrations of nutrients and DOC. We propose a nutrient-DOC framework, combined with hydrological regimes and geomorphic processes, to better predict and understand the relationship between hydrological connectivity and ecological responses of inland floodplain wetlands.