Abstract
[Truncated abstract] Estuaries are unique ecosystems where the river and the ocean meet to create a diverse and ecologically rich environment. Along the freshwater to marine continuum multiple factors interact over a range of spatial and temporal scales to drive estuarine response. These driving factors include both external processes occurring in the catchments and internal factors associated with estuarine hydrodynamics and biogeochemistry.
This study examines how these factors interact and affect nutrient dynamics along the catchment-estuary-ocean continuum of the Peel-Harvey estuary, Western Australia, over the past three decades. Historically, the estuary has experienced eutrophication pressures due to excess fertilizer application on the sandy soils of its catchment and low rates of oceanic flushing. Costly remedial measures have been implemented including nutrient reduction programmes in the catchment and coastal engineering measures including the construction of an artificial channel to connect the estuary to the ocean. In parallel, a persistent drying climate trend experienced across the region has been superimposed on existing eutrophication pressures.
The aim of this research was to investigate, from a holistic perspective, how changes in land-use, remedial measures and a changing climate together combine to affect nutrient pathways through the catchment-estuary-continuum leading to the ultimate response of the estuary. In order to achieve this aim, a retrospective analysis was conducted by compiling historical catchment and estuary data, and applying statistical analyses and mass-balance modelling tools. These analytical tools were used to quantify changes in nutrient dynamics along the catchment-estuary-ocean continuum.
The research itself was arranged into three parts. The first part examined the flow of nutrients through the major riverine systems in the estuarine catchment and assessed how nutrient exports were affected over time by changes in hydro-climatological conditions and land-use. Results showed that despite the drying climate leading to a reduced export of nutrients, there was an increasing trend in flow adjusted nutrient loads. This trend was most evident in the sub-catchments that are most greatly affected by intense land-use change.
This study examines how these factors interact and affect nutrient dynamics along the catchment-estuary-ocean continuum of the Peel-Harvey estuary, Western Australia, over the past three decades. Historically, the estuary has experienced eutrophication pressures due to excess fertilizer application on the sandy soils of its catchment and low rates of oceanic flushing. Costly remedial measures have been implemented including nutrient reduction programmes in the catchment and coastal engineering measures including the construction of an artificial channel to connect the estuary to the ocean. In parallel, a persistent drying climate trend experienced across the region has been superimposed on existing eutrophication pressures.
The aim of this research was to investigate, from a holistic perspective, how changes in land-use, remedial measures and a changing climate together combine to affect nutrient pathways through the catchment-estuary-continuum leading to the ultimate response of the estuary. In order to achieve this aim, a retrospective analysis was conducted by compiling historical catchment and estuary data, and applying statistical analyses and mass-balance modelling tools. These analytical tools were used to quantify changes in nutrient dynamics along the catchment-estuary-ocean continuum.
The research itself was arranged into three parts. The first part examined the flow of nutrients through the major riverine systems in the estuarine catchment and assessed how nutrient exports were affected over time by changes in hydro-climatological conditions and land-use. Results showed that despite the drying climate leading to a reduced export of nutrients, there was an increasing trend in flow adjusted nutrient loads. This trend was most evident in the sub-catchments that are most greatly affected by intense land-use change.
| Original language | English |
|---|---|
| Qualification | Doctor of Philosophy |
| Publication status | Unpublished - 2014 |
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