Aquatic Ecodynamics


Swan River Estuary

Microbial populations and water quality

This study aims to determine how the spatial and temporal patterns of distribution of various microbial populations respond to the highly variable physico-chemical properties of an estuary, and particularly looking at the microbial-microalgal interactions. Harmful Algal Blooms (HAB) research has been predominantly focused on questions concerning population distribution and its abundance. Proactive forecasting and mitigations strategies require the ability to critical assessment and prediction as to why a microalgal population responds to environmental cues. Therefore, this project aims to gain an improved understanding of the water quality dynamics across the ecosystem over a seasonal timescale. In addition, the project aims to relate observed dynamics of the microbial groups measured to various factors; such as hydrodynamics, nutrient loading, and key internal nutrient cycling processes. This study is significant as will highlight the water quality dynamics within the estuary and how they are influenced by seasonal hydrology and environmental conditions. It will provide a valuable contribution to the further improvement in knowledge of water quality dynamics within the Swan Estuary. This will ultimately help support management of the estuary.

A model system for studying the benefit of oxygenation to ameliorate hypoxia

Reduced flows in the Swan River catchments have led to reduced flushing of nutrients and organic matter in the Swan-Canning estuarine system, and changes in the stratification patterns observed within the estuary. In addition, land-use changes within the catchment have increased the organic loading to the estuary. As a result, hypoxia and anoxia in the upper Swan and Canning rivers is a now a persistent management challenge, with detrimental effects on estuarine biodiversity and the overall amenity and health of the river. Artificial oxygenation has been a remediation strategy for poor water quality in the upper reaches of the Canning River for more than 16 years, and in the upper Swan River for the past 6 years. There are currently two oxygenation plants on each of the Swan and Canning rivers (and a third plant on the Canning is planned). These oxygenation plants pump oxygen-depleted water from near the riverbed, supersaturate it with oxygen, and return the newly oxygenated water to the bottom waters of the estuary. Although weekly monitoring of water quality and intensive operational trials around the plants shows obvious improvements in oxygen status due to artificial oxygenation, it is challenging to quantitatively assess the effectiveness of these plants in the dynamic estuarine environment. Researchers from the University of Western Australia (UWA) were engaged in late 2011 to build coupled hydrodynamic-biogeochemical models for the oxygenated zones in the Swan and Canning Rivers. These models aimed to integrate the substantial data sets which have been collected on water and sediment quality in the rivers and provide a predictive tool for management. By modelling the dynamic estuarine environments with and without oxygenation intervention, a quantitative measure of the effectiveness of the oxygenation plants was obtained. Cost-benefit analysis for different operational scenarios were therefore able to be evaluated.

Water quality patterns in the Swan Estuary depicted through remote sensing

Masters Project: Gregg Tidboald, Matt Hipsey and Nik Callow aim to evaluate the potential for remote sensing to measure water quality parameters and potentially the detection of specific focus species (e.g. Karlodinium) in the Swan River Estuary. This project is significant as it is the first estuary application of Landsat 8 compared to high-resolution UAV imagery and in situ monitoring.

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Gedaria, A.I., and Hipsey, M.R., in review. Assessment of seasonal patterns of distribution of Synechococcus and total picopyhtoplankton along a freshwater-marine continuum (Swan River Estuary, Australia) using flow cytometry. Estuaries and Coasts. submitted

Norlem, M., Paraska, D. and Hipsey, M.R., 2013. Sediment-water oxygen and nutrient fluxes in a hypoxic estuary. In: Piantadosi, J., Anderssen, R.S. and Boland J. (eds) MODSIM2013, 20th International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand, December 2013, pp. 1777-1783. ISBN: 978-0-9872143-3-1. Click here for paper.

Hipsey, M.R., Bruce, L.C. and Kilminster, K., 2013. A 3D hydrodynamic-biogeochemical model for assessing artificial oxygenation in a riverine salt-wedge estuary. In: Piantadosi, J., Anderssen, R.S. and Boland J. (eds) MODSIM2013, 20th International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand, December 2013, pp. 1770-1776. ISBN: 978-0-9872143-3-1. Click here for paper.

Gedaria, A.I., and Paparini, A. and Hipsey, M.R., 2013. Integration of cytometric, bio-molecular and nutrient data to explore microbial dynamics in the Swan River Estuary. University of Western Australia Technical Report prepared for the Swan River Trust, Perth, Australia. 94pp.

Gedaria, A.I. and Hipsey, M.R., 2010. Microbial trophic interactions during a Karlodinium veneficum bloom in Canning Estuary, Western Australia. Poster at the 14th International Conference on Harmful Algae, Crete, Greece.