Thesis
Benthic carbon and nitrogen cycling across a land use gradient in South East Queensland estuaries
Southern Cross University
Doctor of Philosophy (PhD), Southern Cross University
2020
DOI:
https://doi.org/10.25918/thesis.137
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Abstract
Estuaries are important coastal ecosystems with a complex mosaic of benthic habitats that can regulate the amount of carbon and nitrogen being exported to the ocean. An increase in land-use intensity (e.g. agricultural production and urbanization) is expected to decrease the diversity of benthic habitats in estuaries, with associated changes in biogeochemical cycling. However, little is known about the effects of land-use changes on estuarine benthic metabolism, nitrate reduction pathways and benthic nitrous oxide (N2O) emissions. This thesis investigates the effect of land-use intensity on benthic metabolism, N reduction pathways (i.e. denitrification, anammox and dissimilatory nitrate reduction to ammonium) and benthic N2O emissions in three sub-tropical south east Queensland estuaries.
Vegetated habitats in sub-tropical south east Queensland estuaries play an important role in regulating carbon and nitrogen cycling with high benthic metabolism and high nitrogen reduction rates, as well as acting as a sink of N2O. An increase in land-use intensity shifted the estuaries from net autotrophy to net heterotrophy with associated increased emissions of carbon dioxide and N2O to the atmosphere, decreased capacity to remove carbon and nitrogen, and increased carbon and nitrogen export to the ocean. These data highlight the importance of benthic habitats in carbon and nitrogen cycling over land-use gradients and need to be included when constructing carbon and nitrogen budgets in estuaries. Synthesising data from this study with previous studies suggests that estuarine carbon and nitrogen cycling between the water column and benthic sediments are closely related and highly affected by land-use intensity. Overall, this thesis shows that land-use change is an important factor in changing estuarine carbon and nitrogen cycles.
Details
- Title
- Benthic carbon and nitrogen cycling across a land use gradient in South East Queensland estuaries
- Creators
- Jian-Jhih Chen
- Contributors
- Bradley D Eyre (Supervisor) - Southern Cross UniversityDirk Erler (Supervisor) - Southern Cross UniversityNaomi S Wells (Supervisor) - Southern Cross University
- Awarding Institution
- Southern Cross University; Doctor of Philosophy (PhD)
- Theses
- Doctor of Philosophy (PhD), Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- 203
- Identifiers
- 991012932800502368
- Copyright
- © ARC LP150100519
- Academic Unit
- Faculty of Science and Engineering; School of Environment, Science and Engineering; Science
- Resource Type
- Thesis