- Title
- Algae-based models to configure consumptive flows for ecological benefit in the highly regulated MacKenzie River, south-east Australia
- Creator
- Atazadeh, Ehsan
- Date
- 2017
- Type
- Text; Thesis; PhD
- Identifier
- http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/162587
- Identifier
- vital:12691
- Identifier
- https://library.federation.edu.au/record=b2746497
- Abstract
- Many river ecosystems, especially those in arid and semi-arid, are experiencing severe stress due to the increasing demands on the ecosystem services they provide, coupled with anthropogenic catchment impacts and factors associated with climate change and weather extremes. The flow regime of the Mackenzie River was substantially modified since the construction of a water supply reservoir on its upper reach in 1887. Water is now regulated at several locations downstream of the reservoir, creating a substantially modified flow regime, impacting key environmental values of the river. The river receives an environmental flow allocation and the river channel is used to transfer water dedicated for consumptive use. Water Quality and algal monitoring formed the basis of models that were developed evaluate the ecological condition of this working river under base flow and before, during and after freshes that deliver water to users. Samples of diatoms, soft algae and measurements of water quality were analysed at ten sampling sites for three years (between February 2012 and November 2014) along the MacKenzie River in different seasons and under different flow regimes to understand the spatial and temporal variation in the relationship between algal communities and water quality, and so stream condition. Baseline information on algal communities and water quality was collected during base flow conditions, while experiments on the effect of water releases on algal communities were based on flow regime variations (manipulated flow regimes), specifically on the algae community structure, water quality and ecosystem function. These comprised cease to flow (0 ML/day), low flows (10-15 ML/day), freshes (35-40 ML/day) and high flow (55ML/day) conditions. Physical and chemical characteristics of water, including pH, temperature, turbidity, electrical conductivity, dissolved oxygen, total nitrogen, phosphorus and cations and anions were measured. Biological properties of the algal periphyton communities, including dry mass, ash-free dry mass, chlorophyll-a concentration and species composition, were also measured. Furthermore, the DSIAR (Diatom Species Index for Australian Rivers) score was calculated to classify the condition of the waterway. The results showed the algal species composition changed under different flow regimes along the river. The sensitivity of diatoms to changes in water quality and flow rates deemed them useful indicators of river condition. The results indicated that flows tended to improve DSIAR scores and diatoms versus green algae and cyanobacteria biomass measures in the mid and lower reaches. The biological properties of the algal periphyton communities, and the species composition, varied between sites under different flow regimes. The accumulation of dry mass (not ash-free) decreased downstream during freshes, however the accumulation of AFDM (ash-free dry mass) gradually increased downstream. The results showed that the concentration of chlorophyll-a decreased downstream under water release events. The Pearson’s correlation matrix revealed flow regimes had a significant influence on the water chemistry characteristics and biological properties. The principal component analysis (PCA) illustrated that upstream species of algae were associated with low pH and temperature and higher DO. In contrast downstream species were associated with higher turbidity, TSS, conductivity, TN, and TDS. The correspondence analysis (CA) and detrended correspondence analysis (DCA) showed a split between algal assemblages during water release events in comparison with before and after water release. The canonical correspondence analysis (CCA) identified five significant environmental variables including pH, TSS, Turbidity, TN and TP explaining algal assemblage and structure along the river. The collected data were used to develop ecological response models based on algae communities living under different flow regimes in the MacKenzie River. The algae-based models across a hydraulic gradient may be useful in water management efforts to find sustainable solutions in the river by balancing environmental and human values. The empirical data and models showed the lower reaches of the river to be in poor condition under low flows, but this condition improved under flows of 35 ML/day, as indicated by the reduction in green algae and cyanobacteria and improvement in DSIAR scores. The results are presented to tailor discharge and duration of the river flows by amalgamation of consumptive and environmental flows to improve the condition of the stream thereby supplementing the flows dedicated to environmental outcomes. Ultimately the findings can be used by management to configure consumptive flows to enhance the for ecological condition of the MacKenzie River.; Doctor of Philosophy
- Publisher
- Federation University Australia
- Rights
- Copyright Ehsan Atazadeh
- Rights
- This metadata is freely available under a CCO license
- Subject
- MacKenzie River; Australia; River ecosystems
- Full Text
- Thesis Supervisor
- Gell, Peter
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