Postgraduate Profiles

Jordan Iles

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Thesis: Biogeochemical cycling of phosphorus and organic matter within arid freshwater ecosystems

In the arid sub-tropical Pilbara region of NW Australia freshwater ecosystems persist under extremely variable hydrology and strong nutrient limitations, particularly of phosphorus (P). However, the biogeochemical processes that underpin the ecological functioning of the streams and rivers of the northwest remain largely unknown. Organic matter can be thought of as a form of energy within the ecosystem, therefore changes to the processes that regulate nutrient and energy availability, such as changes in P fluxes due to wetting and drying, are expected to be reflected in ecosystem functions such as metabolism and primary production. My research will investigate how phosphorus is cycled through organic matter and utilised and conserved across a range of freshwater ecosystems across the Hamersley Basin of the Pilbara, which encompass a diversity of habitat types and hydrology. A mixture of field surveys and manipulative experimental approaches in both the field and laboratory will be used to develop a mechanistic understanding of interactions between systems and the food webs they maintain.

Why my research is important

Australian streams are often particularly low in phosphorus (P) in undisturbed conditions. In more arid regions, phosphorus supply is likely linked to cycles of flood and drought. However, freshwater ecosystems in the Pilbara are under increasing pressure from mining, municipal water extraction and disturbance associated with pastoral activities. Alteration of flows and physical changes in stream morphology from these pressures may impact on freshwater ecosystems in various ways, which are difficult to predict without baseline understanding of how such systems "work". Findings from this research will be useful for strategic planning and decision making around resource management problems in these ecosystems and may be used as benchmarks for assessing ecosystem change and restoration in the future.

Funding

Fortescue River at Crossing Pool (Millstream NP)

Apr 2013

Apr 2016