Postgraduate Profiles

Jen Middleton

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Thesis: Nutrient pathways and processing in urban streams: implications for rehabilitation in a flat sandy landscape

Urbanisation disrupts the function of stream ecosystems, including their ability to uptake and process nutrients. Specifically, urbanisation increases the amount of nutrients (particularly N and P) and reduces the ability of the stream to processes these nutrients. Urbanisation also alters the source of nutrients supporting the food web (i.e., shift from allochthonous to autochthonous energy).

My research will investigate the extent to which urbanisation disrupts nutrient processing and pathways in the urban streams of Perth, Western Australia. Firstly, the project will focus on characterising the biogeochemical composition of stream geomorphic units (e.g. debris dams, pools, riffles) and their ability to attenuate nutrients (i.e. denitrification). Secondly, I will investigate how urbanisation impacts the ability of instream nutrient uptake and movement into the terrestrial ecosystem by examining if stoichiometry shapes the invertebrate assemblage and by determining the sources of carbon supporting the food web.

Why my research is important

Urban streams are arguably the most degraded freshwater ecosystems on the planet. The long length of streams means that cumulatively they could be very important in mitigating nutrient loads. However, currently we understand little about nutrient pathways and processing of small urban streams and creeks in sandy physiographic settings. There is a clear need to better understand what geomorphic, chemical and flow attributes promote ecosystem function in these systems. My intention is that the knowledge gained will assist in the design of living streams, such that they maximise nutrient uptake and recreate the environment necessary for semi-natural ecosystem function.